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 | |  | January 24, 2007 - There hasn't been any construction done on the car in the past few days, but I've still been busy.
I'm talking to a few suspension specialists about options. The JICs (the gold ones in the picture) are an excellent track option, but the spring rates and damping might be a little aggressive for the Targa. We have some new shocks coming in from some other companies with excellent reputations but are new to the Miata, and a Miata specialist is also going to be revalving some stock Bilsteins for us to evaluate. This will be interesting, I'm trying to come up with a good test procedure for them.
entry 15 - tags: suspension | | |  | January 25, 2007 - In order to move the car for paintwork, I installed a rudimentary suspension.
These control arms were used because they're already fitted with polyurethane bushings - but it looks like the right front lower arm is deformed. That's not good. We'll replace that. This is where our association with Flyin' Miata comes in very handy, as we have access to a wide variety of used parts.
entry 17 - tags: suspension | | |  | March 27, 2007 - It's time to install the suspension.
Why? Mostly because I keep tripping over the parts in the garage! But also because that lets me install the uprights and brakes, giving me the chance to bleed the brake system and check for leaks in the new joints.
I considered seam-welding the subframes, but no.
entry 105 - tags: suspension | | |  | March 27, 2007 - The control arms are fitted with polyurethane bushings.
This gives finer control over wheel movement than the stock rubber bushings. They need to be well lubricated though, so I'm using this really disgusting sticky grease.
entry 106 - tags: suspension | | |  | March 31, 2007 - After assembling one corner of the car, I found there was far more friction in the suspension than I wanted.
Closer inspection showed that the crush tubes in the bushings were not as long as the bushings themselves - not a low-friction situation. Measuring the bushing with the crush tube removed was fine, but the deformation of the polyurethane with the sleeve inserted was enough to cause a problem. So I shaved down the bushings slightly so they were flush with the tubes. I only did a couple by hand, the others were done much more rapidly on the belt sander at work. Why did I do two by hand? Because I forgot the control arm at home.
entry 107 - tags: suspension | | |  | March 31, 2007 - The really disgusting sticky grease had questionable lubrication properties but excellent gluing properties.
So I decided to use some marine grease instead. Much better!
entry 108 - tags: suspension | | |  | March 31, 2007 - The rear suspension together, minus the spring/shock assembly.
Because there's no preload in the polyurethane bushings, the suspension is free to droop as far as it wants. This isn't great for the brake line that's currently limiting travel, but it sure makes it easy to work on the suspension.
The rear brakes use 2-piece rotors measuring 11" across, part of a big brake kit from Flyin' Miata. They're lighter than the stock brakes.
entry 110 - tags: suspension, brakes | | |  | April 2, 2007 - The suspension is so eager to droop that it was putting stress on the brake lines - so an extra set of jackstands was needed in the rear.
All four corners now have full suspension and brakes. The brakes have been bled, resulting in just two leaks where I had simply screwed fittings in by hand (just 15 minutes before in one case). The pedal feels really good, a promising sign.
Now that there's steering, a seat, brakes and suspension (without shocks), I have a soapbox derby car.
entry 112 - tags: suspension, brakes | | |  | August 9, 2007 - Finally, some real suspension.
These Öhlins are beautifully built with an obsessive attention to detail in some places and are carefully documented - in Japanese. There's a shortage of numbers so I'm guessing there's little information on setup. I was able to figure it all out though.
They're also very, very short shocks. At full droop, the front wheels are only at about 13.25" from the hub to the fender. That's close to what I wanted to run for static height, so they're unlikely to be the suspension of choice for the Targa. Still, it gives me the chance to test them out and get the car on track next weekend at the Flyin' Miata open house.
The spring rates are approximately 450 lb front and 330 rear. That's a good aggressive street rate, but again a bit more than I'd want for Targa. I went out for a short run after installing them and the ride is very good. There's a suppleness to it that bodes well. On short acquaintance I like them, but I don't think they'll work on the rough Newfoundland roads. We'll see how they work on the track, I don't have much else to test at this point.
entry 279 - tags: suspension | | | August 14, 2007 - So, how does it drive?
The engine isn't fully tuned yet so the car doesn't have full power, nor does it like to idle much. But ignoring those little foibles, it's a blast. The car is conspicuously light. It's surprising just how much difference an extra 300 lbs can make to a car, but it will happily surge forward on even just a tickle of the throttle. Even in the semi-tuned state there's a real snap to the throttle response. The car wants to run, and the short gearing exaggerates this.
The power steering is very light. A bit too light, perhaps. I'll try disabling it to see how that feels and if I'd want to deal with hundreds of kilometers of shattered roads without it.
The car is very rigid, with absolutely no flex - even compared to a modified Miata with a butterfly brace, structural foam in the frame rails and a rollbar. Amazingly, there are no rattles although there's a fair bit of noise and vibration through the uninsulated chassis and competition motor mounts. It's also rather warm inside as the engine and exhaust heat gets nicely transmitted. I'll have to do something about that.
The springs are stiff, but the Öhlins shocks control them very well. It'll be interesting to see how well that works on the track even without sway bars.
In short, the car is a ball to drive. It's a reminder that it's not just a Miata with a cool paint job.
entry 291 - tags: testing, stiffness, suspension | | |  | August 19, 2007 - After that first session, everything dried up and I got faster.
My best lap on the first session had been a 1:12.049. I was concerned that the wheelspin on exiting hard right corners and a banging noise was due to a possibly bad shock, so I bumped up the damping a little to see what would happen.
The results? No real change in the behavior of the car, but then again the track conditions were quite a bit different. The tires were biting now on turn-in, and the combination of excellent initial grip and no sway bars made for a car that required a fairly light touch. I let Bill Cardell from Flyin' Miata take the car out as well and we agreed that the lack of traction on corner exit was probably a wheel lifting. The Torsen differential used in the car is nice when both wheels are on the ground, but once one lifts it acts like an open diff. The lack of sway bars and resulting body roll meant I was getting a lot of droop on the inside rear wheel, and the short Ohlins shocks didn't have a lot of droop to provide. This is something that could be solved by lowering the car - not good for the Targa - or by limiting the roll a bit more. I did test, and the car dealt very well with big bumps such as driving over the kerbs in the chicane.
My time dropped to 1:08.527, mostly due to the dry pavement. This picture was taken on the most difficult part of the track, as I'm accelerating hard downhill towards a braking zone that has the car up on its toes. On my first hard lap, I didn't have the car properly settled before nailing the brakes, and I was rewarded with a spin. Right, no sways and 2050 lbs instead of 1300. After reminding myself of that, I was able to take the late, gutsy option without drama. This corner is an excellent one for dialing in brake balance.
entry 295 - tags: testing, brakes, suspension | | |  | August 19, 2007 - It wouldn't be a track day for me without an oversteer shot!
I was able to throw the car around a bit. By this point, I'd figured out that my banging noise was probably the exhaust hitting the differential. I knew that clearance was tight there, I'll have to get back underneath and take a peek.
The 1:07.977 was my fastest time of the day, and it was a pretty good one. By comparison, a turbo Miata with 225/45-15 Toyos (well scrubbed in) and the JIC shocks turned a 1:07.119. Another turbo Miata was close behind with a 1:07.337, both driven by coworkers of mine. And the Targa Miata was third, ahead of another 45or so Miatas. It was an excellent first day out. The fastest car on the track (1:03.733) was my little Seven, to my satisfaction.
So, what did I learn about the car? I'd like to try a nicely sized front sway bar to cut down the roll, and maybe a bit more front camber. That will make the car easier to throw around, something I'll need to be able to do on the Targa surfaces. Unlike the track, I'll be reacting a bit more instead of anticipating.
The braking is very light, almost to the point of being overassisted. It's the first time I've tried these brakes with the larger booster and master from the late Miatas, and that could be the reason. It could also be the street-only pads I was running (you could smell them at the end of the day) and the fact that I was jumping out of the Seven which has a very firm unassisted pedal. After the first lap, it wasn't really a problem so it may have been acclimatisation. Still, I'll get some proper pads in there and see.
The shocks are the big question. They do an excellent job of damping surface imperfections. But can I run the car high enough to get the ground clearance I need for the Targa? I'll have to drop the rear down a bit and see how it works. There's another set of shocks sitting at work that have 5" of travel and I want to try them next.
entry 297 - tags: testing, other cars, brakes, suspension | | |  | August 20, 2007 - So much for taking a break!
I convinced Bill at Flyin' Miata that the best car for testing this new shock setup would be the Targa Miata, in large part because of the travel available. You can see how much longer they are fully extended than the gold Ohlins shocks are. My only concern is that they'll have too much! We may have to play with the length of the upper mounts to get the wheel to move within a useable range.
Other than size and stroke, the shocks have an aluminum body and are adjustable for both bump and rebound separately. They're not yet on the market, but if they live up to their specifications it should be a nice setup.
entry 300 - tags: suspension | | |  | August 20, 2007 - Well, the droop problem is certainly solved.
The measurement from the hub to the fender lip is 16.5" in the rear and 14.5" in the front - that's a full extra inch in front and a lot more in the rear.
The shocks have SAE spherical joints in them, so they need SAE bolts. In the front I can drill out a 12mm hole to clear the 1/2" bolt, but in the rear the shock bolt goes into a captive nut in the control arm. I'll talk to the shock engineers - they're very responsive - to see what they have to say.
entry 301 - tags: suspension | | |  | August 20, 2007 - I installed the shocks with no springs so I could check maximum travel - and holy cow.
There's 6.75" of travel in the rear, then the suspension starts to hit itself. That's a bit too much bump travel, really - I'd end up with the chassis close to the ground. Maybe I could run very long bumpstops.
entry 302 - tags: suspension | | |  | August 20, 2007 - If you thought the rear had some bump travel, check out the front.
After 5" of compression, the wheel is firmly planted into the fender and the suspension is bound up - and there's still at least 2" of travel left in the shock. That's ridiculous.
Given that there are only 7" springs on these shocks, there's no way I'd be able to use this much travel anyhow. It looks like the car could run 8" springs for my ride height front and rear, but something needs to be done to control that travel a bit. If the upper shock mounts were more like the Ohlins design with the bumpstop flush with the top of the mount - instead of embedded in that big tube - it might be about right.
entry 303 - tags: suspension | | | August 22, 2007 - More suspension testing.
I spent some time on the phone with the shock company yesterday, discussing options. Some of my concerns - such as the SAE vs metric bolt sizes - are due to the fact that this set of shocks is for development testing only. Last night, I measured a number of aspects of the new shocks to determine what would work best and I think I've come up with a good set of dimensions. We'll get those working and then I'll be able to test the new shocks to see how they work. This company has a long race history on rough surfaces so I have high hopes for the end product.
entry 304 - tags: suspension | | |  | August 29, 2007 - A bevy of bumpstops.
I sent my "wish list" of dimensions to the engineers at the shock company. They responded with their recommended shock and shaft combinations. I can't believe how helpful these guys are being. Of course, part of what I'm doing is helping to set up the specification for a potential future Flyin' Miata product, so it's a possible they wouldn't be quite this responsive to an individual racer. But it's great being able to go right to the guys who actually build the parts to ask questions. I'm keeping the name of the company quiet for now to avoid all the detailed questions that FM is expected to answer as soon as a rumor of a product shows up. Let's see if I can get something to work first. There's another set of revalved Miata shocks coming this way for comparison, it'll be very interesting to test the two back to back.
They've asked me to get the car on the road so I can get some rough compression and rebound settings. These development shocks have a wider than usual range of adjustment, and they want me to close in a bit on a more ideal setup. In the front, that meant cutting out about 2.5" of compression travel to keep the wheels out of the fenders. The big bumpstop is crude, but it will do the job for now. That's not full extension, by the way!
I put the car on its wheels this morning and drove it in to work. This is going to be interesting, I've never started with a blank slate before. Initial reactions are a good, a smooth ride with all the hard edges taken off small impacts. Of course, there's only so much I can test driving to work in traffic, so more adjusting and testing will follow. I suspect I'll need a bit more compression damping, but with 7" of rear travel and nearly the same amount in the front, I should be able to absorb just about anything.
entry 305 - tags: suspension | | | September 1, 2007 - Suspension tuning continues.
It's a fascinating process. I know intellectually what adding more compression or rebound damping will do, but it's something completely different to start with a blank slate and make the car work. My initial settings had too much compression and not enough rebound, and I'm gradually sorting that out. The car's working better and better, and will be on track again next Friday. It'll be interesting to see what a difference the extra droop travel makes.
entry 307 - tags: suspension | | | September 6, 2007 - Lots of time spent working on cars, but not much on the Targa car.
I've been waist-deep in changing the engine on my old Toyota pickup. It makes me appreciate the amount of room and relative simplicity of the Miata engine bay, that's for sure.
I have been driving my "baseline" Miata around to help recalibrate my butt for the suspension tuning. The baseline setup is a set of Flyin' Miata springs with Tokico Illumina shocks and Flyin' Miata upper shock mounts. Despite using 17" wheels, the ride/handling compromise is an excellent one. The spring rates (318 F/233 R) are what I'd like to use for the Targa. The current suspension setup I'm working on uses 450/300 so my goal is to get the same compliance despite the higher spring rate. I think I'm on the right track. There's a short window for some track testing tomorrow and I'll see how the new long travel setup compares to the previous short travel Ohlins. The big question - should I install swaybars for the trackday?
entry 308 - tags: suspension, other cars | | | September 7, 2007 - Track test for the new suspension.
This was an informal and short window of opportunity, but it was enough to take the car out with the new setup. I spent some time on the phone with the suspension engineers and learned about bit more about how my valving worked.
On the track, the car felt pretty good. It took a few laps to discover where the difference lay. The first hint was the chicane area. There are some big berms here and the car is usually dancing around due to the kerbs throwing the car around and the nature of the entrance to the turn. Not today. The car was just swallowing any bumps, including ones where it was off balance before hitting the kerb. Coming down the hill into the tough braking zone, I discovered that it was impossible to upset the car. I started provoking it, coming in off-line and hitting berms when the car should have been vulnerable. Nothing. It just stopped. I think the endless rear travel kept the rear wheels on the ground no matter what, adding greatly to the car's stability.
A bit of experimentation with compression damping helped balance the car a bit better and gave it more composure in the corners. At the end of the day, the car was forgiving and able to deal with just about any imperfections I could find on the track. Imperfections like dropping off the outside of kerbs on corner exits, or cutting corners so that I'd drop inside the kerbs, or hitting kerbs under hard braking. It isn't quite the super-playful Miata yet but I have some ideas for extracting the last bit of fun.Maybe a little more front camber and a front bar to encourage faster turn-in and a slightly flatter stance. I don't want too much of a wayward tail for the Targa, though. On the street, the car feels good.
There's a set of 8" 350/275 lb springs on the way along with some rubber snubs to limit the travel a bit better than my rough-and-ready bumpstop arrangements. The spring rates are closer to what I'd like to run on the Targa, although the way things are working right now I'm not sure how critical that will be! They're also an inch longer than my current setup so I can get a little more ride height, and throw some relatively soft sways in there as well.
Tomorrow, Targa 2007 starts. Good luck to everyone!
entry 309 - tags: testing, suspension | | |  | September 14, 2007 - Some more suspension parts to try out.
This is a set of 8" long springs (1" longer than my current ones) with a 300/225 split. It's closer to the rates I was planning to run on the Targa and I'll be able to lift the car a touch. The rubber bumpers are to control travel a bit on these prototype shocks, although I thought they were going to be longer.
entry 312 - tags: suspension | | |  | September 20, 2007 - Spring time!
The (chrome) 450/300 lb springs have come out and the (yellow) 300/225 springs have gone in. The new springs are an inch longer as well. This is the spring set I've been expecting will work out best for the Targa.
How does it feel? After a quick run around the block (the block in question is not your average city block, but includes some low speed turns with bumpy exits, some mild crests and is probably 6 miles around) it's pretty good. It's time for a sway bar of some sort though, and I need to do a back-to-back comparison with the control car. The most obvious thing is that I could probably use another inch of spring length on the front to get the nose up to my desired ride height, but it's very functional right now and I have piles of travel. So maybe I don't need to raise the nose after all.
entry 314 - tags: suspension | | | September 25, 2007 - I drove the car in to work today with the new springs.
It's gained a fluidity that I really like. I haven't had the chance to stretch its legs yet but I'm hoping to do that tonight. I'll put on a front sway bar soon and see if I can arrange a bit of track time to test the setup.
entry 317 - tags: suspension | | |  | September 28, 2007 - Sway bar time!
I have a good selection on hand. For the front, a 23mm front bar from a Mazdaspeed MX-5, a 7/8" adjustable aftermarket bar and a 1" adjustable. The rear will be served with a 14mm Mazdaspeed bar or a 5/8" adjustable. I'm trying a different setup than I usually use to ensure the rear wheels stay hooked up on rough surfaces. We'll see how this works out. I might see if my local alignment shop is willing to work with me on this, I expect it'll be spending a lot of time on the rack.
entry 318 - tags: suspension, alignment | | |  | September 29, 2007 - I have quite a collection of end links for sway bars.
From the left, we have 1999-05 stock, a set of adjustable ones with rod ends, a pair of Racing Beat ones with bushings and stock 1990-97. I'm using the rod end style because I have a full set of four and they will allow me to adjust the length and avoid any preload. These particular ones were made with inexpensive rod ends, and thus make a slight rattling noise. It's not a problem, just a little disconcerting when driving through a parking lot.
entry 319 - tags: suspension | | | September 29, 2007 - The sways are installed.
There's a 7/8" bar on the softest setting up front and a 5/8" bar on the softest setting in the rear. I considered using the 14mm Mazdaspeed bar in the rear, but the aftermarket version has longer arms so I suspect they're about the same in the current setting - and this gives me more options. This current setup is slightly more biased towards front stiffness than I usually run. Typically I'd have that rear bar on the middle setting. I also have a factory 12mm rear that I can throw on if required. One nice thing about the Targa Miata is that I can install the rear sway bar without even jacking up the car, thanks to the cutaway rear bumper!
I headed out for a run to test the bars. To make things more exciting, the wind was howling and rain was splattering down. It's the best imitation I've seen of Newfoundland weather here in the Colorado desert. I'm assuming I won't have to dodge tumbleweeds in the rain in Newfoundland, though.
The car feels great. It's got a very nimble feel and it just glides over imperfections in the road over 20 mph. Below that speed there's more impact felt through the body but the car just deals with it. One 2nd gear corner with a very corrugated exit caused the rear end to lose traction, but it had more to do with the cool tires, wet road and too much power than with the damaged pavement. The Torsen diff let the loose wheel just spin up, an indication of how little traction there was. It was a smooth breakaway and I just rode it out. The car is very eager to turn in and feels a bit darty, but that could also be the strong cross winds. I'll see how it feels over the next few days. The next track session is scheduled for November 3rd, but I might be autocrossing the car next week. We'll see.
entry 320 - tags: suspension, drivetrain, testing | | |  | October 17, 2007 - So, what's the first thing you do after a successful race?
You take the car apart, of course. The shocks are going back to the manufacturer to be modified. Different bodies, different shaft lengths - this will give me the travel range I've requested. They're also going to come back with a bit more granularity in the adjustments, I believe, and I'll gain the ability to run the front a bit higher. Good, I need the ground clearance.
The next track test - a big track this time - is on Nov 3rd. They say they can turn the parts around fast enough. We'll see.
entry 326 - tags: suspension | | |  | November 1, 2007 - The reworked shocks are here.
These shocks are the ones I expect to use for the Targa. They're made by AFCO, a US company that has experience in both road and dirt track racing. They're pretty exotic and have a number of features designed for maximum durability and traction. I've been hugely impressed in dealing with AFCO so far, having a number of long discussions with the engineers about the damping, stroke and bumpstop design. These shocks will become part of the Flyin' Miata lineup, and they are definitely a custom item built to the Miata's needs.
The new shocks are quite a bit different than in their original configuration. For example, the fronts have a 2" longer body. After installing the original set, I made a number of measurements and sent them off to AFCO. From this, just about every component of the shocks was changed - the upper hats were shortened, the bodies changed in length and the shafts altered. Now I have the exact travel range I requested. I can also run the car a bit higher than I did before - not something that other Miatas will necessarily want, but it'll give me the ability to absorb all sorts of rough surfaces. Eric wants me to jack the car up to Paris-Dakar levels, but that might be a bit extreme.
One nice side effect is that they're also easier to install. Not that this is a critical aspect of shock design, but I sure appreciated it when it came time to put them in.
Today I'll cornerweight the car, then get it aligned. I'm experimenting with alignment settings that are closer to those used in Spec Miata, unlike the street-biased ones I've used in the past. The testing on Saturday will be used to determine how it works.
entry 331 - tags: suspension, alignment | | |  | November 4, 2007 - The track day was with the Peak-to-Peak Miata club and took place at Pueblo Motorsports Park.
I was last there in March and it's a track that's fairly familiar to me. Not the greatest track in the world, but it does have a couple of interesting corners. More importantly, the club runs the track day as an open format. There are no run groups, so you can enter and exit the track whenever you want. This makes it excellent for both driver and car development and takes a lot of the tension out of a day. It wouldn't work with a group of unknown drivers, but these days tend to be invitation-only and everyone uses their heads.
For me, the goal was to sort the handling out and see how my new alignment worked as well as test the suspension at high speed. The first few laps felt good - the car was composed, but it was uninspired. There was a little bit of understeer. Very stable, but I didn't have the adjustability I wanted. So I installed a stock 11mm rear sway bar, as the car had been running without one. As you can see, the trailer makes an excellent sway bar adjustment rack.
That was better. The car was a bit more adjustable and turned in better, but it still wasn't quite there. I popped on a 14mm rear bar from a Mazdaspeed MX-5 and voila, we have a Miata. The car came alive with a great handling balance and excellent adjustability. It could dance.
Meanwhile, I also took a few sorties to work on the suspension tuning. A bit more rear compression damping, a touch more rebound and the car was able to handle just about anything on the track. I was driving over berms and trying to upset the car, but to no avail. One corner did give me the ability to bottom out the suspension, but I had to hit a berm at full cornering force to do it and it didn't upset the car at all. Once again, I found that I could move the rear end around if I wanted but it was still very easy to control. I believe this is due to the long travel available, keeping the wheels well planted on the ground. There are other suspensions out there with decent travel, but most will unweight the spring before reaching full extension. Not in this case!
There's one spot on the track where the exit berm on a corner has big bumps or teeth in it. On one lap, I brought the tail out on this one and went around with the rear wheels going over the teeth at full throttle. It was bumpy, but it didn't upset the car. That's the sort of composure I need.
The last turn on the track is a fast one that has widely varying surfaces as it travels across a drag strip. This means you go from patched asphalt to VHT-soaked asphalt to coarse concrete to VHT to asphalt again, with a couple of metal plates thrown in for good measure. Oh, and it's bumpy and you take it at wide open throttle in 4th gear. In a stiff car, it's painful and the car keeps skipping around. In the Targa car, I could feel the changes in lateral grip but the car didn't get upset at all. Very nice - I think we have a winner with this suspension setup. The Torsen differential was working as intended as well, putting down the power smoothly and cleanly.
So, all very promising then. I was able to run down and pass a Spec Miata which was gratifying, as he was running a much more track-biased suspension than I was. His front spring rates are more than double mine! There was a good battle with a Subaru STi that was promising as well, my handling and grip were able to make up for a 150 hp (or so) shortcoming.
Bill Cardell of Flyin' Miata tried the car and was impressed. The suspension he considered to be "suitable for a NYC taxi" because of the way it would absord anything. The engine feels good but it really needs more top end, that's something we'll work on. His only concern was the brake bias, as I have it a little strong in the tail for maximum braking. This means that the tail feels a bit loose in some situations. Not a problem on the track where you know exactly what the next corner looks like, but he pointed out that with the unexpected nature of the Targa course this could be a liability. Luckily, that's easy to adjust, even between corners.
So that's the good news.
entry 335 - tags: testing, suspension, brakes | | |  | November 6, 2007 - I pulled the differential out last night so I had the car up on the lift for a good check-over.
Underneath the nose, the plastic ducting for the radiator got smashed up in one corner. Easy to replace. The engine undertray got pulled loose from one bolt but a washer will solve that problem. I can fix up the paint damage easily enough of course.
There's no other sign of damage underneath although I'm still wondering why the steering wheel is offset. It has me worried as you might expect. I'm considering replacing the left front control arm regardless, that's the corner that hit hard enough to damage a strong SSR wheel.
About the wheels - I took a new wheel and the bent wheel/tire down to our local tire shop to have it mounted and balanced. I was waiting at the door when they opened up in the morning, as I needed to have the wheel and tire back on the car by the time Flyin' Miata opened for business so I didn't tie up a lift. First thing on a Tuesday morning, it should be quick. Not so much. It took over an hour for the single tire to be mounted and balanced and I had to be a bit of a pest to make that happen. A dramatic contrast from the friendly, speedy (and free!) service from Discount Tire in Pueblo. I wasn't wearing the race suit, that might have been the key.
entry 337 - tags: crash, suspension | | |  | November 12, 2007 - This wheel used to have about 1.5 degrees of negative camber.
Now, it has none. A quick check with the toe plates indicates close to an inch of toe-out. Once I'd pulled the shocks out again (they're going in a street car for final evaluation as a Flyin' Miata product), I also pulled out the lower control arm on this wheel. Yup, looks like a crease in the top. That would explain the alignment problems.
Honestly, after bending a wheel like that, I'd be shocked if the control arm hadn't bent. They're intended to be the weak point in the suspension, absorbing the punishment to protect components like the subframe. I'll stick another control arm in, that's an easy fix.
entry 339 - tags: suspension, alignment, crash | | | November 19, 2007 - Comparing the new control arm to the one removed from the car, I can't measure any difference.
The crease I saw is normal. That's not completely reassuring, I'd like to know what's up with the alignment. I'll put things back together and see if I can get the car sorted. The subframe appears to be undamaged.
The suspension can't go together until the springs and shocks are back from street car testing. They're performing well though.
entry 340 - tags: suspension, crash | | | November 23, 2007 - Back on the wheels.
The AFCO shock setup is still under evaluation in another car, so I grabbed a set of springs and shocks from the pile at Flyin' Miata and put the car back together. I used a new front lower control arm for the time being because I have one, but measurements seem to indicate that there was no problem with the original. An initial check of the alignment would indicate that everything is straight, but I will have to drive the car to make sure everything's settled first.
So, the car's back on its wheels and drivable. The next step is some dyno work, to see if I can liberate a few more RPM out of the car. The engine is great down low, it just needs a bit more sparkle up top. I did come across a stillborn product at FM that might be handy, I'll have to keep scrounging for parts to make it work.
I need to get cracking on a lot of the detail work that needs to be done on the car. Items like the codriver footrest, the required gear and a way to stash it, and various electrical accessories that have been neglected. There's always something...
entry 341 - tags: suspension, crash | | | December 4, 2007 - The car is all healthy.
I finally got around to taking it for a short test drive after catching up on some of the rest of my life. Using the scientific method of the steering wheel location when driving in a straight line, it appears that I have a healthy car. When it came off the track, the problems meant that the steering wheel was badly off center. Now it's almost right, which means I just need to align the car and I should be good. The car sure is dusty, and the temporary suspension that's installed sure isn't any good!
So, it's time to get down to work. I have a good list of jobs to do on the car, all in nice bite-size chunks. None of this "weld in roll cage, build an engine and paint a complex paint scheme" that I had before. I have some time between now and the new year so it's an excellent chance to get a lot of the required detail work done.
I also took the opportunity to take both my Mini and the Seven out for a spin yesterday. In all three cases, the last time the car was driven was either on the track or the autocross course. I think that's a promising sign.
entry 343 - tags: crash, suspension, other cars | | | January 2, 2008 - Well, my local shop can't source the 2" radius bends I need.
So it's off to Summit Racing for them.
I've also been chatting with the engineers at AFCO. The shocks are off getting a tweak to the valving, based on shock dyno tests of a few other options that did well on the comparison drives. I feel like such an amateur when talking to them, but every time I learn something and the shocks seem to come back a little bit better. This should be the last iteration.
entry 363 - tags: header, suspension | | | January 8, 2008 - A big box of pipes arrived yesterday.
Janel didn't seem to understand my excitement. Oh well. Now I just need to get up the nerve to start cutting and tacking tubes. It's a big step, but I know from last time that a solid day's work should show good progress. Last time I didn't have the cool design tools I do now...but I also had a much simpler header to build.
In other news, the shocks are revalved and should be heading back this way shortly. Not that I can drive it right now, the diff is gone and of course the engine bay is full of blue snakes.
I've also been talking to the new technical director for the Targa. As you may remember, the cage I'm using is an SCCA Spec Miata cage. I was given the okay to use this, but it doesn't meet the Targa rulebook. Well, apparently it does meet the approval of the new tech inspector with the exception of door bars. They're putting an emphasis on door bars for 2008. I'm going to have to find space to stick another one in there on top of the one I have now. I think I know how I'll fit it in place. Hopefully I won't have to disassemble the car too far to weld it.
entry 364 - tags: header, suspension, safety | | | February 19, 2008 - It's alive!
Finally, after being in drydock for months, the car took a trip out of the garage. This means that I've managed to get my hands on the race shocks again (yes), the exhaust system is complete (yes) and I had some time to work on it all (yes).
Initial reactions to driving with the header? Well, it doesn't leak. I didn't have the laptop attached to the computer so I don't know if the engine's asking for more fuel - that's an indication that it's making more power. I'll do that in the next few days. But the car feels good. And it's a bit stinky as that new white paint cures into a light tan.
The suspension feels pretty good, but I got the height wrong when I first installed it. The car's about 1 to 1.5" too low right now. I did install my stiffer springs (450 lb/in front, 300 lb/in rear) at first but almost immediately pulled them out to install the softer 300/225 setup I've been using. While the stiffer setup would be good for a more track-biased car or even an aggressive street car, they're too stiff for the combination of my very light car and the rough roads I need to absorb.
entry 409 - tags: suspension, header | | |  | February 21, 2008 - I spent a few minutes setting an approximate ride height for the car.
Nothing too precise or difficult, but it gets me into the range I want instead of being slammed down low. The driver's rear was down at around 12" (measured from the hub to the fender) so I lifted it up to 13.25". This is a ride height that works pretty well on a street-driven Miata and I think it'll be a good combination of ground clearance and CG location for the Targa car. I'm running 13" in the front. This will be fine-tuned later after the car's up to its final weight with a full load of tools, spare tire and other gear.
I did take a quick spin in the car last night to give the defogging system a test. It worked - if I turned off the fan the window would start to fog up a bit, but flipping it on cleared things up nicely. It wasn't a harsh test, but it was the best I could arrange in our climate.
So, time to install the intercom. First, I need to install the amplifier box itself. This needs to be accessible while driving so I can adjust the volume. It also needs to be accessible so we can easily change batteries - assuming I don't hard-wire it into the car. So I put it in front of the shifter, then spent a bit of time making sure the wires were properly corralled. Everything is on rivnuts so I can quickly pull the intercom (a Peltor FMT100, by the way) out of the car and install it into another. And because I haven't posted many shots of the cockpit, here's the big view!
entry 410 - tags: suspension, intercom, ergonomics | | | February 28, 2008 - The car's back from the alignment shop.
Just like last time, the left front won't get as much camber as I'd like. As I've (probably) mentioned before, I'm experimenting a bit with the alignment on this car and running more camber than I usually do. Right now, it's got a "traditional" alignment like I've been using for years. That's not such a terrible thing, but I'm a bit disappointed I can't try the new setup. Maybe I'll bung a couple of adjustable bushings in that control arm. I'll have full access to an alignment machine in a month or two.
So the car's looking pretty complete now. Why the recent improvements? There's a track day coming up next weekend at Pueblo. Janel and I will be testing the intercom, computer and general compatibility in-car. It should be fun.
entry 420 - tags: suspension | | |  | March 1, 2008 - I think this will be the final ride height for the car.
I usually measure from the center of the hub to the bottom of the fender, as that's a measurement that's independent of wheel/tire sizing. It's about 13" front, 13.25" rear. Just to be more accurate, I decided to use the bottom of the frame rails to confirm the car was sitting level. After all, my fenders have been a little reshaped. Turns out I was dead on on all four corners. Good!
I like the stance. It's obviously not a road racer, but it looks capable. I have ground clearance and lots of travel, but the car's not unstable. We'll see how it likes the track next weekend.
entry 425 - tags: suspension | | |  | March 10, 2008 - Time for another test.
After a long tow through some nasty weather (check out that filthy hood!), we made it to Pueblo for the most recent testing session. The goals for this one were primarily to work on the driver/navigator team, although as always suspension tuning was involved.
After a late start due to a car that was stuck on the track with the doors locked and the engine running (!), I took the car out solo in wet (and rapidly drying) conditions. The brakes didn't feel good. A nice solid pedal, yes. But I wasn't getting much feedback. This kept up over the whole day so I'm not sure what's going on or if it was just a matter of a lack of faith on my part. Since I was planning on making some big changes to the pads shortly, I'll look at them more closely later.
The car felt pretty good. The handling balance with the new alignment wasn't right on the first session, it was a bit too biased towards understeer as I'd expected. Not terrible and certainly stable, but I do generally prefer a car that's set up to be a bit on the loose side. The suspension was swallowing up just about everything. Just about?
The final turn has been reconfigured to make it much tighter than before. It will be repaved this summer, but for the time being it's rough. Really rough. There was a deep dip in the pavement right past the apex that was bottoming out the suspension hard. When I crawled under the car to do some sway bar adjustments, I noticed that the left rear spring had marks indicating it had hit coil bind. Ahh, that's not good. The fairly high ride height and the 8" springs were a bad combination. Since I didn't have any way to deal with it, I played with the corner to avoid that hole for the rest of the day. Elsewhere on the track, I was able to drive over berms - even the rough "dragon's teeth" ones - with impunity. So that was working well. Despite a slight understeer in fast sweepers, the car was both faithful and mobile when I was setting up for corners so it's probably a pretty safe setup for the Targa now. It was quick enough to let me pass a Lotus Elise without any difficulty, that's a good sign.
I'm going to try a couple of things to sort out that coil bind. There are a set of 10" springs on the way to replace my 8" ones, as they'll give an extra 1.25" of spring travel and that will avoid the binding. They're a 250 instead of my current 225 so I can make the rear slightly more mobile. I also ordered some 375 lb springs, thinking I could try a 375/300 combination instead of my current 300/225. The stiffer springs not only give an extra 0.5" of spring travel, they'll use a lower perch height for the same ride height so binding should not be a problem. Now, do I want the extra stiffness or do I keep the car fairly soft? I'll have both options available to me.
The header worked perfectly all day, not showing any signs of weakness or cracking. That's good.
entry 431 - tags: testing, suspension, header | | |  | March 13, 2008 - This is what coil bind looks like.
See the marks on the springs where the coils came together? Not good. What's interesting is that the right side is almost completely free of marks. The perch on that side was 8mm lower. That's the margin of error I was dealing with. Why did this happen? Because I put the wrong bumpstop for my ride height in the shocks. Whoops.
No worries, I have others. I also have those 10" springs coming. The big question is - do I try the 375/300 combination, or do I install the 300/250?
entry 435 - tags: suspension | | | March 26, 2008 - The shocks are back in the car.
I installed the 375/300 springs. They'll get their first test on Sunday at another Corvette autocross. Hopefully I'll get a chance to throw the car into a few hard corners first so I don't discover lots of oversteer by accident. I'll have some tools with me!
entry 440 - tags: suspension | | |  | March 30, 2008 - I have a few road miles on the 375/300 spring combination, and I really like how it's working.
It's a good balance between supple and responsive on the road. Very nice, I think this will be the final spring setup for the race.
entry 443 - tags: suspension | | |  | April 5, 2008 - Another trackday test.
This was on our local kart track, the same track used for the car's first track day. I wanted to see how the suspension was doing, and see if the car could put power down.
Immediately it became apparent that the track was fast today. My existing lap record fell almost immediately to a turbo Westfield. That was set in the Seven, so I didn't have a chance to fight to get it back. My own times were quick as well though, as I ran times that were quicker than we've seen from Miatas here before. Recent rain has left the track much cleaner than usual, I suspect.
On track, the car felt great. The suspension is almost perfect, allowing me to take completely ridiculous lines through the chicane. I wasn't just putting the wheels on the berms, I was dropping off the other side and essentially straight-lining the course. I never bottomed out and the car wasn't upset at all. Only once did I scuff the bottom of the car, and to do that I had to put my outside wheels where most people ran their inside ones! We shot some video of the car from behind that shows my fairly ludicrous lines, I'll have that posted before too long. When I took my friend Mark (last seen welding the roll cage into the car a year ago) out for a ride, he was amazed. "It doesn't feel like a Miata, it feels like a rally car!". He was also impressed with the feeling of stability and adjustability in the car, as it just gripped and gripped and never seemed to get upset. The car and I are bonding, and it's become a very useful tool. Bill Cardell took a break from hammering on my lap record to take the car out for a run, and he was quite impressed with the setup as well. The new brakes with the Performance Friction front pads really worked nicely, hauling the car down remarkably fast with lots of stability. There are a couple of corners on this track that really test both braking and stability so it was a good venue.
Unfortunately, the car again showed an inability to lay down any power in a right turn. I started running with ballast (aka passengers) after the first session, and that seemed to help somewhat. But still, it's acting just as if there's an open diff back there. So either I got it wrong and installed an open (again!), there's something wrong with my Torsen (I can't think of how that would happen) or for some reason the suspension setup is unweighting that inside wheel. Given the amount of droop travel available, I doubt it's the latter. The car feels exactly like it did with the open diff back at the Open House testing, although I blamed a short-travel suspension for the behavior then. So step one is to confirm it's a Torsen for sure for sure. I'm also going to cornerweight the car and see if it's way off, but still. A turbo Miata running almost exactly the same tires (225/45-15 instead of 205/50-15) and an extra 130 hp was not having the same problem.
So how did I do? Well, I had the fastest Miata there at 1:04.989, running clockwise. That's 1.5 seconds faster than we've seen a Miata go around the track in that direction, I think. Running counterclockwise, I ran a 1:05.228. I even beat that turbo Miata on race tires. The only cars that went faster were the turbo Westfield and that STi from last weekend. No shame there! In the case of the turbo Miata, it was a matter of suspension versus horsepower again. That car's fitted with a JIC Magic suspension and is very competent on the track. It's just not quite as competent. That car was also being piloted by a very good driver who knows the track well, so it's fair to say that most of the difference was in the car.
entry 445 - tags: suspension, testing, brakes | | |  | April 9, 2008 - Video time!
I've just added three videos of the car running through the chicane at the recent track day. Honestly, the videos downplay the size of the hit the car is taking, but you can still get an idea of how well the suspension is coping. I don't know if I have an in-car shot yet or not.
For those who are wondering, the chase car is a turbo Westfield.
First pass
Second pass
Third pass - the car is completely unruffled in this one.
I forgot to mention in my last update that I set the lap record for Miatas last weekend. Not bad!
entry 446 - tags: suspension, testing | | |  | April 14, 2008 - Naturally, the first thing I did after coming back from the track was tear the car apart.
It's what I do. The main goal was to pull out the diff and ensure it's a Torsen. Yup. But while digging around, I discovered that the upper control arm was hard to move. The bolts seem to be too tight, as backing them off slightly lets the arm fall down easily. I'll retorque them according to the factory specs and see what that does. I'm also going to cornerweight the car to see what that does for me.
entry 448 - tags: suspension | | | April 14, 2008 - Here's a little more thinking on the traction problem.
I was sharing the track with two other Miatas of similar speeds. One was running the RA1 in a larger 225 size, the other was running the Falken Azenis RT615 - not quite as sticky as the RA1. Both are making considerably more horsepower than my car. And neither was having the same traction problems. Here are some of the theories that have come up.
- My differential was the later 2003+ style, which doesn't work as well as the earlier Torsen Type 2s. Well, so was the diff in the 2004 Mazdaspeed that was sharing the track with me. I'm not 100% sure which kind of diff I have although I do know it's an LSD.
- It was a cornerweighting problem. There's some validity to that, as I haven't cornerweighted the car well for a while and the passenger's side was certainly more of a problem than the driver's. But I'm pretty sure that one of the cars out there hasn't been cornerweighted either...seeing as I'd probably be the one that had to do it.
- The inside wheel is lifting up due to the extra roll afforded by the suspension. I'm having trouble with this one, mostly because I can't imagine I'm lifting a wheel with the amount of droop available. One of the other cars was fitted with the FM upper shock mounts which allow a similar amount of upwards travel, but not as much droop.
- I didn't have the right damping and I was getting wheel hop. Okay, now I think we might be getting closer. At the autocross the week before, I'd been playing with rear damping to control hop off the line. But I think I backed it off a couple of clicks afterward. So this might be worth investigating.
- I have a bushing problem. A late arrival to the though process after the discovery over the weekend. Going back through my memory banks, I can think of one other car that had this sort of behavior - and it also had polyurethane bushings. Hmm. Neither of the other two cars on the track did. So this is definitely worth pursuing. I'll try ensuring they work smoothly first, then bung in a set of stock control arms (and bushings) later if that doesn't help. Now I just need to come up with a testing regimen that doesn't involve the track!
entry 449 - tags: suspension | | | April 20, 2008 - I put the car back together and took it out for a test drive this morning.
The upper rear control arm bolts are a bit looser to allow for free movement of that arm.
I used a piece of road I haven't used with this car before, but it's perfect for per-Targa testing. Incessantly twisty with a lot of blind corners, covered in gravel in inconvenient places and with completely hammered and badly patched pavement.
The car did quite well. I wasn't at full throttle very often but I never had a lack of traction. Even at inadvisable speeds through the roughest, twistiest sections the car never got upset although it did make some interesting movements. I'll have to go back through there with a more normal car to get a baseline. I'm also going to take Janel for a ride to make sure she's comfortable with it!
entry 451 - tags: testing, suspension | | | May 7, 2008 - There's an excellent article in the latest Grassroots Motorsports.
It compares a pro-built Spec Miata against a couple of amateur cars. Great stuff - but what caught my eye is that the pro-built car has the exact same traction problem coming out of corners that mine does. It's played up as a positive ("it helps the car rotate") but it's probably worth noting the pro driver was faster in an amateur car without the problem. The interesting thing here is that these cars should all be running the same components, from bushings to shock valving. Hmm. Could it be a problem with an individual differential?
entry 453 - tags: suspension | | |  | May 25, 2008 - I took the car out for a run on the local "Targa simulation" road.
It's rough and twisty and gets gravel on it. I wanted to play with suspension settings a bit as well as see how the car does with putting down the power out of corners.
The suspension setup worked just fine. One hammered area had the car moving around a bit much, but a slight tweak to the rebound solved that nicely. As for the inner wheel wheelspin on right hand turns - well, it doesn't seem to be a problem. I'm realizing that both the autocross course and the local gokart track are much tighter than most turns in the real world. On the "big track" at Pueblo I don't have a problem. So, I think I'll just let this slide - or just bung the Guru in for the race and avoid it completely.
I'm still driving at "fast road" speeds, though. There's an overall speed limit of 200 km/h (120 mph) during the race, and in the open sections I'm trying to imagine going 50 mph faster. And having Janel deal with me going 50 mph faster. She's been alongside me at 10/10ths on the racetrack, but I think it will be quite a different matter on real roads.
The list of things to do for the race is getting shorter, but no less critical. I still have to add a door bar (a different focus in the regulations here) , figure out how to mount my tools (and what tools to bring) and deal with a number of small things to ensure I don't have a hectic day running around St. John's to solve problems. But it's starting to look pretty good. So maybe I can start working on engine output again.
entry 460 - tags: testing, suspension | | |  | June 1, 2008 - Autocross time!
This was an event put on by the Red Rock Racers, a group I started because we didn't have any autocrosses to go to! Problem solved, now there's one a month. And on the prettiest autocross course in the world.
We had a good bunch of cars out - a couple of modified STis (including one on Toyo R888s), a rotary-powered X1/9, some quick Miatas, an Evo and even a Isuzu I-Mark "Handling By Lotus". Everyone's a lot of fun to run with. However, they did have a little trouble keeping up with the Targa Miata. I took the fastest time of the day by a 0.8 second margin.
The car felt good, moving around nicely and easy to toss into corners and transitions. I was using the brake bias to adjust the handling of the car and it worked well. I didn't adjust anything on the suspension after my recent over-the-road testing otherwise.
The picture was taken on a fast right sweeper, and you can see there's a fair bit of body roll. It didn't seem like it from inside the car and it responds to transitions pretty well. But I was still having traction problems on rights, and looking at that roll makes me wonder if it is simply a matter of unloading the inner wheel completely despite all that droop. I'm going to play with some different sway bar and alignment settings, although having Janel in the car helped and I expect a cornerweighting session would also plant that right rear a bit more.
Another thing that concerned me a bit was my consistency - or lack thereof. I'm usually pretty good for putting down similar times, but today I was all over the place on the timing board. Still at the pointy end of the pack, of course, and I posted not only the fastest time but also the second-fastest and (I think) fourth and fifth-fastest. But there was a bigger range than usual. I'm not sure exactly why. I did manage to stay clear of cones all day though.
The car was burping coolant out of the overflow tank, but not showing signs of running hot. I think I might have a bad radiator cap that's venting early. Easy enough to check. Otherwise, the car ran flawlessly.
entry 462 - tags: testing, suspension, brakes | | | June 12, 2008 - I put the car on the cornerweight scales last night.
No surprise, the right rear was the lightest corner of the car. That's how Miatas are. But it wasn't extreme, and the cross weights were actually pretty good.
I drove the car to work - the long, long way - this morning to see how it likes the new cams. It feels pretty good, although I just cannot make it idle at all. Of course, when I got to work, I found out that I had the closed loop autotuning turned off, so the car didn't do any fuel tuning. Whoops. I'm going to double-check the cam timing to make sure it's at least close, then probably change idle modes in the Hydra to the "big cam" setup that uses the TPS instead of MAP.
entry 475 - tags: suspension, tuning | | |  | June 16, 2008 - I swapped out all the control arms for new ones this weekend, as planned.
I'll get it aligned on Wednesday, then we'll see what effect this has on the car. It does appear that I have more negative camber up front, which is good. Not very much of it, but more.
While I was under there, I welded this little ramp on the lower rear control arms. The adjuster for the shock protrudes through the arm just slightly. It's not something I'd be worried about in any other car, but just in case I drop a wheel off the edge of the road this should provide a bit of protection for the adjuster. It ended up being taller than it needed, but that's better than too short!
entry 476 - tags: suspension | | | June 17, 2008 - I had the car aligned today.
I had a 9 am appointment and the car went on to the (empty) rack at 10. Sigh. Still, by 11:30 it was all lined up and looks to be a decent job. The right front wheel wouldn't give any more than 1.4 degrees of negative camber, which is a bit of a shame. I was hoping for about 0.5 degrees more. It could very well be my ride height, of course. According to the Spec Miata Constructor's Manual, I should be able to do a bit better. But I know from hanging out with certain Spec racers that it's not unusual for the upper control arm to be accidentally and carefully bent a bit, giving more camber. Good book, by the way.
So, how does it work? I took the car out for a run on my local Targa Simulation Road (assuming the Targa has pinon tree, red rocks and 95F temperatures) and it feels pretty good. The front end sticks beautifully and it puts power down well. Of course, I'll have to take it to the track to see if the low speed, tight radius wheelspin is gone but fast road work is not a concern. I still want to spend a little more time fine-tuning the shocks but I feel the car would be quite competitive at the Targa as it sits.
The new padding for the seats seems to work quite nicely. It wasn't a 2+ hour test, but so far it's an improvement.
I also spent a bit of time tuning the engine with the new cams. They don't like to idle much, but I'm starting to get that under control. The car feels pretty strong and it's adding a whole pile of fuel at 4500 rpm or so - right where the previous cams had a big dip in power, and right where I need a big slug of torque. So far they're promising.
entry 478 - tags: suspension, testing, ergonomics, tuning | | |  | July 25, 2008 - A very interesting picture provided by a fellow racer.
He's entering a corner at about 40 mph. This car is fitted with the AFCO suspension, but with much higher spring rates and big fat Hoosier 275s. Check out that lifted rear wheel!
Cory reports that his car is sitting higher than he'd like, about the same as the Targa car is. This is because he's running 800 lb springs in the front and they're not compressing as much as my 375s, thus he ran out of adjustment. You can really see that in how high the car's sitting even in this position, the front still has another couple of inches of travel left. Some shorter springs will solve that, and it will give him some more droop travel.
He's also not running much swaybar at all when compared to his springs. It's a 7/8" bar up front, and he reports lots of oversteer. So he's going to try dropping the car by about an inch and sticking a much larger bar up front.
I find this interesting because it may be related to my wheelspin problem. I've never seen a picture of my car with such unbalanced cornering though. I'll be playing with ride height a bit at the track tomorrow to see if I can alter the behavior - or even to see if the car wheelspins in that environment.
entry 502 - tags: suspension | | |  | July 28, 2008 - The final high-speed testing took place on Saturday.
In short, the car performed well. I had a brace of sway bars along with me to do some tuning, but it wasn't necessary. The overall balance of the car is pretty good. On long sweepers, it can be balanced on the throttle well. I've set the car up to be a little bit softer on turn-in than I usually do for a track-only car, in order to give myself a little more margin for error. Still, it'll rotate nicely if I set the car up properly on corner entry.
I did play with the ride height a bit to see what that affected. The car's a bit sharper and less prone to understeer at the lower height, which is about the same height that we use for street Miatas at Flyin' Miata. It's easy to adjust so I'll leave that as an adjustment option once we get to Newfoundland.
I tried driving a few different lines around the track to see how the car would react. It's amazing how much slower you get when you're driving like a normal person instead of a racer who knows every little bump in the course. Still, it was good practice and the car was a good tool - mobile and friendly. Even a fast entry into the fastest corner on the track, with a different line than usual, was dealt with well.
The car ran flawlessly and cool despite 30+ minute sessions in brutal heat. I need to spend a bit more time on the dyno to tune the engine but overall it's pretty good. I declared it finished at the track.
Well, finished except for one thing. The tight corners on this track tend to be lefts. There's one relatively tight right hand 180 degree corner, and on that one I could get the inside rear to spin up once in a while if I was brutal on the berms. This was without a passenger, so it probably wouldn't happen on the Targa - but I've decided it's time to solve this problem once and for all. I'll pull the Guru differential out of my Seven and install it in this car. The Guru is a helical-style diff like the Torsen, but with preload so it won't act like an open diff when one wheel loses significant traction. I'll swap that over this week. I'm just trying to decide if I should have it changed to a 4.10 ring and pinion or stick with the 4.30 that's on it already. I do prefer to drive the taller setup, so I'll probably go with that.
The trailer towed really nicely, and when we hit lots of rain on the way home I was happy to think that my little car was safe and sound inside. It's not cheap to tow, but that's life.
entry 504 - tags: testing, suspension | | |  | August 1, 2008 - The differential is out again.
I'm going to use velcro to put the goofy thing back in again.
It's out so that it can be replaced with the Guru from the Seven. What the heck, even if I don't need it I'll have it. The Guru is currently set up with a 4.3 so I'm having the gears swapped around. I was tempted to try it myself, but this close to the race and with such an expensive part at risk I decided to try it some other time.
While underneath, I noticed that the last alignment tech set two of the four rear alignment bolts upside down - you can see one at the far left. I'm not sure if this is going to be a problem or not, but I'm not impressed regardless. My usual long-time alignment guy seems to have retired.
entry 505 - tags: suspension | | |  | August 9, 2008 - A great shot from the last trackday at Pueblo.
The car's sitting nicely - this is a fairly fast corner with a quick dab of the brakes on entry, a bit of rotation and then back on the throttle. At least, that's how I do it. And I always exit this corner saying "next time, faster on entry..."
Back to the present day - the diff is in and working nicely. I'll know just how nicely after tomorrow. A surprise track day has come up at the Woody Creek track in Aspen, courtesy of the 25th anniversary gathering of the original quattro. This isn't a track we get a chance to drive very often. It's relatively short but is bumpy in spots and has a couple of challenging corners. I've only been on it once before. I'm going primarily because Janel has to work and because the weather forecast is poor. Hopefully it'll rain. It's not the usual wish for track work, but I don't have much experience in fast driving in the rain and I need the practice!
I have my new race tires all mounted and balanced. If it's rainy, I'll scrub them in and see how full-depth RA1s work in the wet stuff. Quite well by all accounts. If it's damp or dry, I'll use my well-seasoned test tires. I'm also going to drive the car out to see how the new padding works in the seat.
There's a Sport Quattro in attendance at the event. I can't wait to see one in person.
entry 510 - tags: testing, suspension, ergonomics | | |  | August 10, 2008 - In terms of rain, the trackday at Aspen was a failure.
For me, anyhow. One run group of Audis was lucky enough to get wet. I was the only one disappointed, however. Nobody else is any fun.
The day started with a really early morning (8 am driver's meeting and a 2.25 hour drive to the track). The good news? The new foam in the seats makes all the difference. No numb bum at all. That's a big win for the "backsaver" pad from Pegasus racing. Insert glowing testimonial here.
The bad news? The 8 am driver's meeting was at 9:50. My car was given a tech inspection four times. This kinda gives you an idea of the level of organization present. Still, we finally worked out way out to the track. I was staged right behind three Formula Fords that had me a little spooked - Aspen's track is a little on the small side, and I didn't want to accidentally squash one that had sneaked into my mirrors. That wasn't a concern. My biggest problem was trying to get one to give me a point-by. I had the same acceleration, better cornering and vastly better brakes than the driver in front of me, but he apparently didn't have mirrors. After seriously considering using the old "chrome horn" on an open-wheeled car, I ducked into the pits to get some clear track.
The car was okay, but it was hunting for grip. Both ends were skating. I checked the tire pressures and found I had them too high. The next session was better, but still too much hot pressure. Finally things settled down a bit. The car's quite safe right now, giving me lots of warning of what it's about to do. For a track car, I think there's still just a bit too much understeer. Of course, that means it will understeer, even mildly, on occasion. I can throttle steer the car fairly well. But given the unknown nature of most corners in the rally, that's a good setup. In my opinion, anyhow! I'll have the ability to tweak it at the rally if required.
And while it may not have been my preferred setup, a chicane at the fastest part of the track was handled very nicely, a high speed right-left jink that could have been a real problem if the car oversteered too much. Instead, it just screamed right through and surprised a few cars. I was also informed that my lap times were very good for running two-up with a chicane on the straight. Considering my lack of knowledge of this track, I'll take that as an endorsement.
So, despite the lack of rain, a good day. I had fun playing with some purpose-built race cars (who were a little surprised to see how fast this particular Miata could squirt out of corners) and Brandon had an excellent time bonding with his new Locost. Smiles all around.
entry 511 - tags: suspension, ergonomics, testing | | |  | August 24, 2008 - Another track day.
Yes, August has been a busy month! This time, the Targa car stayed in the garage. There was no need to beat on it any more, and I was busy defending my shiny new lap record in the Seven. So I took the old race rubber off the Targa car and stuck them on Janel's little Miata so she could have some fun. She did pretty well, taking a second off her previous best time.
I took her car out for a few laps to show her how much she could trust the race tires, and it was an interesting drive. Her car is fitted with a small, responsive turbocharger (an FM Voodoo II with the smallest turbo) and has a number of chassis braces installed as well as a Flyin' Miata Stage 2.5 suspension. Peak power isn't much different than the Targa car although it's a more civilized drive due to the full interior and a bit of extra sound deadening. But other than the lack of a full cage, it would be a good specification for the Targa for much less work and cost than our purpose-built racer. It uses off-the-shelf components and the whole car would cost less to duplicate than building a Spec Miata. It would have to run in the Unlimited class thanks to the turbo, however.
On the track, the car felt softer. The suspension dealt well with the berms, although I wasn't taking anywhere near as many liberties with them! The car had good power that was easy to control, friendly handling and nice brakes. But everything was just turned down and softened a bit. The brakes were nowhere near as aggressive, the power response wasn't as hyperactive and the car just didn't have the sharp reflexes of the full-on race car. I didn't have a transponder on the car so I didn't get times, but I'd guess it would be at least a couple of seconds a lap slower. That will translate to a lot of time over the course of a Targa stage. This isn't a big shock and I was quite happy with how friendly the blue car was to drive. It's under full braking in the picture, in case you're wondering. That's Janel setting a personal best.
One piece of good news: while the bruising to my hands did make things a little less comfortable and meant I didn't have much grip strength in my right, it didn't seem to slow me down. By the time the Targa rolls around, I'll be just fine.
entry 517 - tags: skills, suspension, other cars | | | September 22, 2008 - How did the suspension work?
On smooth stages, it was a joy. The car worked perfectly, giving me enough stability for confidence but remaining nimble enough to deal with surprises. I was able to adjust my line through corners without surprises, late braking didn't upset the car and I even ended up with some fairly high-speed trail braking by accident. In those situations, I could feel the tail getting light, but it never bit me.
On moderate bumps, the travel was good. We were able to soak up some big imperfections, especially on the high speed stuff. We could always put the power down.
The rough stuff - it's difficult to describe just how rough some of the stages are. The fact that on at least two occasions, we went over sharp speed bumps that weren't even in the notes is probably a good indication. For those stages, I needed better bumpstops, stiffer rear springs and more ride height. The Subaru guys were running gravel suspension, if that's any indication. The front end of the car worked really nicely, it was just the rear that wanted a bit more. Also, at full compression in the rear we were planting the rear subframe brace into the pavement so we actually had a bit too much compression travel for this sort of behaviour.
I raised the car a bit over the course of the week, but I was hesitant to go too far in case I damaged the high-speed behaviour. I'm going to keep working on this so I can find out how to make it work better. But holy cow, those were some big hits. The car never got upset and the chassis was protected enough to prevent any damage, but I usually have a bit more mechanical sympathy than that. I did get a report from my uncle Rob that while I was grounding out at times, it wasn't as bad as some of the other cars.
The shocks did gave us a scare early on as we discovered we'd blown right through the bumpstops and damaged the seals. The non-pressurised design of the shocks kept them from losing performance in this case, though.
entry 604 - tags: post-race, suspension | | | September 22, 2008 - Over the entire course of the race, the car never surprised me.
Not once. I never had to wrestle with it or deal with wayward behaviour. It simply did what I asked and always gave me an option in case I wanted to do something else.
In short, it was a Miata.
That left me free to concentrate on Janel's instructions and the road. I can't emphasize how important that was - it's why others commented on how smooth we looked. The car simply didn't have any bad habits. More than a year of constant testing and thousands of miles at race speeds in this and other Miatas were a real benefit, as the car's handling is second nature to me and heck, they flatter any driver.
entry 605 - tags: post-race.suspension, testing | | |  | October 15, 2008 - When I pulled the shocks out to send them back to AFCO - they're going to be tested and rebuilt with a few tweaks - I discovered coil bind marks on the rear springs.
I'm guessing the destroyed bumpstop allowed the extra travel to put the spring into bind. Ouch! I'm glad nothing got damaged, and I didn't realize I was that close.
Lessons learned from the Targa have already been put into place on newer AFCO shocks, so the bumpstop damage would be avoided now. The amount of dirt on this shock must have arrived on the last day, as I was monitoring the shock during the race and never saw it look like this.
entry 637 - tags: suspension | | | November 4, 2008 - The race might be over, but development continues.
The shocks are off at AFCO being tested and rebuilt, and they'll be reinstalled with a new bumpstop design. Whether we take part in the Targa again in the future or not, I'm going to keep working on fine-tuning the car.
entry 641 - tags: suspension | | |  | November 19, 2008 - The car's currently sitting on jackstands as the shocks are being repaired.
It'll be a while before they come back because I'm waiting for a newly developed part that will support the bumpstops. That was the source of our problems during the race - the bumpstops couldn't handle the impacts and deteriorated, leading to the damage to the shaft seals and also to the increased travel that gave us tire rub under braking (you can hear it in some of the videos, such as at the beginning of Mooring Cove) and helped the rear subframe brace ground out.
The good news is that there was no internal damage. There was some fluid loss, which would have led to low damping on small shock movement - but the big movements were still damped. So the suspension kept working despite the pounding. I knew this, but it's good to have confirmation.
Once the shocks come back, I'll reassemble the suspension and keep testing. I think I'm going to move to a stiffer spring rate to deal with the bigger bumps, and see if I can reach the alignment numbers I want at a taller ride height.
Why the picture? No reason, it just looks good!
entry 642 - tags: suspension | | |  | January 2, 2009 - The shocks are back from being rebuilt.
After a long rest on the jack stands, the car is going back on the ground shortly. The reason the bumpstops failed during the race was because they were not properly supported on top. These blue cones are the solution. After testing on the bench, they've improved the function of the stops nicely. I'm also going to try a few different kinds of stops along with these, mirroring some testing I'm doing on Janel's street Miata.
The rear shocks were also rebuilt with an extra inch of extension. Just because! I'm going to reassemble everything with stiffer springs, going to 450/375 instead of the previous 375/300. Why? To see how it works and to keep me from working through all my travel no matter what. Now all I have to do is find a road that's as bad as some of those ones in Newfoundland. And that's bad.
Oh, and some wheels and tires I can use in sub-freezing temperatures.
entry 644 - tags: suspension | | |  | January 18, 2009 - Out of the garage!
It's been a long hibernation, but the combination of sunshine and warm(ish) temperatures meant that I was able to pull the car out today. It was the first ride with the new spring setup and new bumpstops. I wasn't impressed at first, but after a couple of adjustments of the AFCOs I got my supple ride back. Next step is to find a place to open it up and see how it works at high speed and high bumps.
Before it went out, I spent a bit of time fixing little things like the air temperature sensor and the fans. For the latter, I started by hooking up the laptop and changing the fan "on" temperature to 10C. As soon as I hit enter, I could hear relays click underhood. First, that's cool! Second, that tells me that all of the difficult-to-reach wiring was working fine.
Next step, I decided to trace the power. And voila, one blown fuse. I'm running both my fans in parallel, and the startup surge must have been just too much for the fuse at some point. The Hydra has the capability to trigger them one after the other, looks like I'll have to take advantage of that. The car was getting warm while waiting to start the second stage in the Prologue, I wonder if the fans were out then? For most of the race, cooling wasn't a problem.
Boy, it's nice to get back behind the wheel. It's such a fun car.
entry 647 - tags: suspension, fans | | | January 20, 2009 - A beautiful day outside, so I headed for the Targa Simulation Road.
It's the first time I've driven it since the race. It's not a perfect simulation, mostly because it's fairly tight. And it is rough because of road slippage, not because of frost damage. So the bumps tend to be more undulations instead of sharp hits, although there are a couple of good ones that really test how the car deals with a dip mid-corner. So it's a reasonable test. And since it's about 5 minutes from my house, it's a lot more convenient than Newfoundland!
I took several runs through the worst section, playing with the shock settings. A couple of tweaks to the rebound and a big crank on the compression knobs, and the car's livened up a bit and able to deal with some really weird pavement. How will it work at Laguna Seca? Excellent question. I'm going to have some spare springs with me just in case the smooth, high-speed track needs a different setup than my battered back-road tune.
Really, this is just an excuse for tearing up and down a twisty, empty road on a sunny day. But can you blame me?
entry 648 - tags: suspension | | | February 6, 2009 - I took the car in to work yesterday.
It's been too long since I drove it much, I keep forgetting how much grip it has and how light it feels. What a riot.
It needs a bit of work before the Laguna Seca event, though. The windshield cracked at some point on the way home, so I need to get that replaced. More worrisome is a noise that sounds like it's coming from the rear of the car. My initial thought was "wheel bearing", but it's fairly noticeable and it just started. So something's rubbing or moving - possibly a brake dust shield on a rotor, for example. I can make the car make a weird noise about once per tire rotation by simply pushing it across the garage floor. I'll get underneath and have a look. I suspect it will be an easy fix if I can stop working on Janel's MG long enough to get under the white car.
I'm really wondering if I should keep these springs, too. The car feels very eager to turn and is fairly flat, but it's lost the suppleness it had. Maybe I'll play with the shocks a bit more and see if I can come up with something that will deal with cratered roads but still keep the ride fairly plush. I was happy with the 375/300 combination until we hit the really rough stuff in Newfoundland, but the car should like the stiffer springs at the track. So many options!
entry 649 - tags: suspension | | | February 11, 2009 - The TV show has been scheduled on Speed TV.
Sunday, March 15th at 3:00 EST. Details. Oh boy oh boy oh boy!
In unrelated news, I think I found the noise in the back of the car. The first thing I did when investigating was to put a wrench on the lug nuts. Whoops. I'm usually very, very careful about the lug nuts so I can't come up with a good explanation. Heck, there is no good explanation. I haven't driven the car yet, but it would explain the nature of the noise. None of the wheels were actually loose which does explain the lack of vibration though.
entry 652 - tags: TV, suspension | | | March 6, 2009 - I spent the afternoon at the local track, playing with the car.
It wasn't a completely satisfying day, as I was having trouble getting the handling just the way I wanted it with the stiffer springs. I'm really torn as to whether I should use the current setup or the Targa setup at Laguna Seca in a couple of weeks. Really, I need the extra stiffness for the track. And I probably could have used it in Newfoundland as well. I'll probably take it as-is and then stick the extra springs in the truck for a Saturday evening change if desired.
My biggest problem was getting the balance right. I think if I put the thinnest rear sway in my collection in the rear, that will do the job. The car was a little tail-happy with the current 14mm bar hooked up. My lap times were inconsistent, with a fastest of about 1:05.2 - a half-second slower than at the Open House just before the race. An ambient temperature in the 50s instead of in the 90s may be a contributor, as is the fact that the track isn't getting used much at all in the winter. I did spend a bunch of time trying to get that right rear wheel to hook up on corner exit. Again. Not liable to be a problem at Laguna though.
Janel took the wheel for a bit. She's not a huge fan of driving the car, it turns out. She's happier in the navigator's seat. The Targa car is just a bit overwhelming. The amount of information was a bit of an overload and the car was just too responsive. Her turbo Miata (which I compared to the race car back in August) is a little softer and a little mellower. Everything happens a bit more slowly and gradually, and that's more to her liking. At least, right now it is.
At one point, she was back in "her" seat watching my feet to see how I heel-toed on downshifting. She didn't feel the need to look up at all, as she was totally relaxed despite the fact that we were circulating the track fairly quickly. This is the result of the Targa.
And on a similar note, I have to say the Targa has spoiled me. I've got hundreds of laps at this track. I know it pretty well. And today it was all just kinda blah. The same dozen corners, over and over again. After you've come over a blind crest at 100 mph with your foot pinned to the floor because your navigator says it's clear, or changed your approach mid-corner because there's gravel at the apex, circulating around the same track over and over just doesn't carry a thrill. I'm sure it would be different if I was running wheel-to-wheel with someone, but we have to get back to the Targa. Janel feels the same.
entry 659 - tags: testing, suspension | | | August 5, 2009 - I pulled the suspension out today to install some upgraded bits and pieces.
Nothing major, just detail stuff. At the same time, I reinstalled the "rally springs", the 375/300 combo we ran in the Targa. I've got some different bumpstops installed and we're running a slightly higher ride height, so let's see how this works. I do enjoy the fluidity the car gains with this softer setup, but will I miss it on the track?
Well, I'll find out on Friday. The Flyin' Miata Open House (now called Summer Camp) is this weekend, and I'll be running yet another track day as part of it. The FM staff aren't allowed to run transponders to prevent us from all chasing the lap record (again), but I'll put the Traqmate data acquisition system in and see what interesting stuff pops loose.
entry 687 - tags: suspension, testing | | | October 26, 2009 - I've been doing some testing on the suspension of the car.
As usual! This time, I'm running some very stiff 750 lb front springs with 450 lbs in the rear. Usually I'd run a higher rear spring rate with that much in the front, but it was a matter of what was on hand. The car works surprisingly well on the road, even though that front rate is exactly double what we ran in the race. It's going to be a lot of fun on the track this weekend for sure, with some very quick reflexes right now. In fact, the rear rate seems to be working pretty well. Well enough to make me wonder what I should run in the next Targa. I'd been leaning towards 450/375.
While under the rear of the car swapping in a larger sway bar to keep the handling balance with that "soft" rear spring setup, I saw fresh shock fluid on the right rear shock. That wasn't there when I swapped the springs a few days back. Interesting...
entry 713 - tags: suspension | | | November 2, 2009 - Track day time!
The new 750/450 springs worked quite well, pretty much eliminating body movement but allowing the suspension to still soak up those berms in the chicane. The car was fairly quick as well, allowing me to match my best-ever time of 1:04.7 despite a cold day and slow times for most people. Janel also liked it, posting a personal best and getting down into the 1:10 range. She's not a big fan of the feel of cold race tires on the warmup lap. There was actually ice on the start/finish line when we arrived in the morning, I'm not exaggerating about the cold!
The shocks are dealing very well with the rates, even keeping the car comfortable on the street. It's lost that very smooth ride it had for the Targa, of course. Bumps are dealt with without upsetting the car, but it doesn't seem to repave the road the way it did. I'm still playing around with what the best spring setup for the race would be in the event that we get to go back. 450/375 and some good ride height? Probably. For track use, these heavy springs are obviously the way to go.
entry 716 - tags: suspension, testing | | |  | March 1, 2010 - I'm not done with the intake yet, but first I need to play with some springs.
Why? Because the 750 lb springs on the car are borrowed, and they have to go on to a V8 Miata instead. And just today, I got a package from AFCO with my dual spring setup!
With the stiff springs I've been running, I don't get much spring compression with the car's light weight. This means that the spring will unload before the shock is fully extended. Most people think this is bad because the spring can rattle around and they imagine it means it can land crooked. That's not the problem. The problem is that I lose suspension travel. Once the spring unloads, there's nothing to open up the shock except the weight of the wheel fighting against the fairly stiff rebound damping.
The solution, then, is a helper spring. A short, relatively soft spring that is usually fully compressed but helps supply that extra push when the main spring is fully extended. I've run into two problems with this setup. First, most helper springs are just a little bit undersize in their inner diameter. AFCOs are set up for 2.625" springs but can run 2.5". I haven't found a helper spring from another setup that will fit. More importantly, most helper springs are wussy little things that just keep the main spring from rattling around. Rates like 5 or 10 lbs/in. That's nowhere near enough to extend my shocks when they're valved for the big springs.
AFCO sells 4" springs with a 300 lb rate. It's about double what I'd prefer, but it's the best I can find. The potential problem with this is that it won't fully compress at rest, so the light spring is still active until the car hits a bump or rolls. The weird thing is that the spring rate of the two springs combined is less than either of them. So I'll have a fairly soft rate until all of a sudden it spikes up. How will this work? I have no idea. But I'm willing to give it a try in my science experiment of a car.
My other problem is that because the helpers are 4" long, I need a fairly short main spring. That's a front shock with a 7" 600 lb main spring. I'd prefer a 6" (like the 750 I just removed) but it is not to be. At the lowest ride height I can manage, I'm running relatively high - the front wheel-fender measurement is 12.75". That's about where I was when I got back from the Targa, and I suspect this setup might actually work well.
It's not so pretty in the rear. I have a 7" 450 lb spring back there, but even at a perch height that's a bit lower than I can really use, the car's an inch too high. I'll need a shorter main spring. I have my eyes on a 5" that's 425 lbs. These spring rates (once the helpers are compressed) should give me a similar handling balance to the Targa spec. We'll see.
Fun stuff!
entry 730 - tags: suspension | | |  | March 16, 2010 - I started the day planning to do some dyno testing on some intake variations.
But first, I had a couple of parts to install. First was a couple of springs for the rear, so I could get the ride height into a reasonable range. That was quick and easy.
After that, I decided to put on an ATi damper. Since the car's seeing a lot of constant high rpm use on track, I figured I'd like a bit of extra margin of safety for the oil pump. Besides, it makes the engine feel smoother and the guys at Flyin' Miata suspect there might be a bit of power in it. We'll see.
Unfortunately, the install of the damper and a few other jobs ate up my spare time so the dyno didn't happen. Soon, though.
I did take the car out on the road for a bit of a test drive with the new intake setup. The Hydra was able to autotune itself into a happier place - I suspect I never set up the part-throttle tuning after the fuel pressure change, and so it's running really rich at anything but wide open. Before the changes to the fuel system, the fuel pressure was tied to manifold pressure so I'd see a drop in pressure under vacuum. Anyhow, a half hour drive later and the car's much happier. And pretty fun, once you get used to the heavier throttle pedal. The dual spring suspension is working pretty well - it's quite comfortable on the highway and on smaller bumps as the softer spring takes the hit, but you can tell there's some real stiffness behind it. I think, on track, it's going to have an initial bit of lean and then the car will take a very solid set. Would it be a good Targa setup? I don't know. I need some more seat time.
I did think of one potential problem, however. The Laguna Seca weekend that's coming up in a month or so has a very high 102 dB sound limit - almost unheard of at Laguna. Janel's also going to be driving on Friday with another group to get some private instruction from our friend Rick Weldon. Well, that group probably has a 92 dB limit, and with the current intake setup I suspect the car isn't going to meet that limit.
entry 731 - tags: suspension, intake, damper, engine, sound, laguna | | | March 18, 2010 - More thoughts on the dual spring suspension - this is interesting.
Just for fun, I pitched the car into a couple of the right angle bends on the way in to work. I figured I'd dance with the tail a bit. Now, I haven't been behind the wheel of this car for a while but I've been driving a number of other Miatas. And the car seemed to grip much harder than it should. We have another car at Flyin' Miata right now running a completely different dual-spring setup, and it's showing similar characteristics. Mechanical grip seems to be way up there.
It's going to take more investigation, but I am quietly optimistic. We'll see what happens on the track in a few weeks. Will I go back to the stiff single springs, or keep this dual setup?
entry 732 - tags: suspension | | |  | March 28, 2010 - Here's a before-after peek at the wide angle lens, taken up on the Targa Simulation Road.
I think I need to move the camera up a bit in the car, but the wider field of view helps a lot with the sensation of speed. My other concern with the camera had been the lack of image stabilization, but that's not a problem. In fact, the video was rock steady even on this very bumpy road. So that's a big winner then. I'll post the video soon - that's another advantage to the Flip. Very easy to post video to various hosting sites.
I was up on the Simulation Road to see how the new dual-spring suspension worked. Pretty well, I have to say. After a couple of stops to set the shocks (it never ceases to amaze me at how one click makes the difference between "hmm, it's okay but not great" and "wow!") the car seemed pretty happy. This is a tough stretch of pavement and the car was certainly pitching, but it was stable and well-connected to the road. I doubt it would have worked as well if I'd been running the main spring rates alone - 650 and 425 lbs, I think. That's a lot of spring! I'll take it out on the highway later today to see how stable it feels at speed without the massive headwind and with the shocks set up.
entry 735 - tags: video, suspension, testing | | | March 29, 2010 - Another new video.
This is a run up the Targa Simulation Road to test both the springs and the video camera. I'm pretty happy with both. We'll see how the springs do on-track this weekend.
Video
entry 739 - tags: video, testing, suspension, video | | |  | May 16, 2010 - Road trip!
The big Miatas in Moab event took place this weekend, and I headed down to say hi. It's only about 75 minutes from my house to the lodge where the event was based on Saturday. The crowd at this event is almost the exact opposite of the folks that were at Laguna Seca a month ago, and the race-scarred Targa car did stand out. Most of the attendees didn't have roll bars, and nobody else had brake dust on their wheels, well-scuffed race tires and a cage! Still, there were a lot of fans of the car and it did get a lot of attention and I spent a fair bit of time talking for various Miata enthusiasts from all over the US. I also took a couple of people out for test rides in the newest V8 car - yowza, that's a fast, fast car. As you can see in the picture, the Targa car got the prime spot for the big group photo.
One excuse for this little excursion was to test the dual-spring suspension a bit more. It had acquitted itself fairly well at Laguna, although with a lot of roll. On the highway, it felt a bit odd. The change in spring rates definitely make it difficult to get the damping right - it's either heavily over-damped on small movements or under-damped on big ones. I have it set up for the former.
I did find out where it works best, though. There's one way to get to Moab from Grand Junction that runs across a few miles of abandoned road near a ghost town. It's paved, but fairly rough. And at "targa speeds", the suspension ate it up. I can see this setup working well on Leading Tickles, for example. The car just went supple and absorbed almost everything.
It's not perfect. A really big hit would bottom out the rear hard. Granted, I'm running a track ride height and not a Targa height, so there's at least an inch of travel missing there - but I think the problem is that the secondary spring rate is too close to the primary. The effect is that the secondary spring never really closes up, so the rear spring rate is too low for too long. I'm planning to pick up some new secondaries that are around 150 lbs as opposed to my current 300, and I think that will address all of my concerns with this setup.
It never stops. I'm always trying to make this car better!
entry 757 - tags: Moab, suspension | | |  | July 16, 2010 - I've been working on other cars, and the Targa Miata has been sitting.
"Sure boss, I guess I'll drive the supercharged 2006 at the track day to see how it does" - that was actually a really good track day, as it poured rain. The combination of a powerful car on wide street tires and heavy rain made me work on some skills that could prove very useful at Targa.
But the car hasn't been forgotten. I've removed the 300 lb secondary springs to cut down on that initial body roll and sharpen up the car's reflexes. The radiator was removed as part of some cooling system testing and has ended up in Janel's street Miata. The differential is coming out so we can test a different unit. All of this should be on the track in a bit over a week.
But when I was working on the car, I discovered a problem. I know the Performance Friction PFC97 pads are hard on rotors, and I've been watching the slots on the rotor as a guide of wear. But when the wheels were off for something else, I took a closer look and was shocked. The rotor in the picture used to have slots! The outer face still has lots of meat and isn't showing dramatic wear, but the inner face is completely worn away. Both front wheels were like this. Yikes. I also discovered a cracked rear rotor.
So, what happened? Good question. The brackets on my brakes are from a source that often needs a bit of shimming to get them aligned well enough to clear the rotors, and even then my calipers are off-center on the rotor. I wouldn't think a 4-piston caliper would matter, but the brackets are being replaced with new ones that are perfectly designed and machined to keep the caliper centered. New rotor rings are on the way. Flyin' Miata is also testing a different brake kit that will be on the car for the next couple of track days, so there's no big hurry.
I have new rotor rings on the way to replace these.
entry 758 - tags: brakes, suspension, cooling | | | August 24, 2010 - I spent part of the day replacing the differential.
I'm going to try out a new unit that's a clutch-type instead of the Guru helical I have now. The car's tendency to spin an inside wheel on right turns should be abolished!
Or should I say, the car's old tendency. At the Open House, I didn't have any trouble with that. I always had a passenger which does alleviate the problem - but likely more important, I was running a different spring setup with a lower ride height than usual. I also didn't have the rear sway connected, but I know I've run without it before. Interesting. It could have simply been the passenger and the fact that I've been driving other cars and taking lines that alleviate wheelspin. Anyhow, it'll be interesting to see how this new diff turns out.
I've also pulled one of the front shocks off. Due to an assembly error on my part, it was leaking pretty badly at the track day and acting very poorly on right turns - maybe that was the secret! The good thing is that if an AFCO leaks, you can just refill it with the correct oil and it's as good as new. I have the oil, so I'll top it up and test the result on the track by Sept 4th at the latest.
entry 760 - tags: suspension, differential | | |
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THE DIARY