| MIATA BUILD |
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 | |  | 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 - Turn one was a bit of a fast one.
As the day went on, I was starting to figure out how to drive the car better. The biggest trick was getting a good drive out of corners, and it led to me taking some different lines than I usually do in the little lightweight weapon. The Seven has a huge amount of traction, but in the Targa car I was taking wider lines to settle the rear down first. It was paying off, my fastest lap dropped to 1:07.977.
I've found a satellite picture of the track here . We were running counter-clockwise, and the big sweeper is the fun part. My goal is to start braking when my left front wheel hits the kerbing before the hairpin.
entry 296 - tags: testing | | |  | 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 19, 2007 - All the kids were available for rides at the Open House.
Orange is my Seven, yellow is the FM Westfield I helped to build and set up, white you know and blue is my wife Janel's little turbo Miata. The Targa car was pretty popular, both amongst people who had never heard of it and a bunch of regular readers who were exited to see it in the metal. Turns out I'm not the only person who thinks the stripes look good. It's obvious from the pictures at the track that the black FLYIN' MIATA on the nose and tail really stands out as well.
One thing I discovered on the test drives - I was leading my coworker Brandon in his turbo Miata that makes approximately 230 hp at the wheels and weighs around 2350 lb or so. When I put the throttle down, he could keep up. But he didn't seem to be gaining ground. Wow, maybe the engine is working better than I thought. It sure feels great, and it has just the flexible nature I'll need.
entry 298 - tags: other cars, Martini | | |  | August 19, 2007 - Interior shot.
It was pointed out to me that I haven't shown the final result. With the hardtop on, it's hard to get much of a picture, but here it is. It's a spartan interior that needs a bit of heat insulation, but it's a start.
After the recent push to get the car ready for the track, I'll be taking a bit of time at a slower pace. It's time to catch up with everything else in my life, but the Targa Miata is only at the beginning of its development...
entry 299 | | |  | 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 | | |  | August 30, 2007 - Quite possibly the coolest course maps ever.
The Targa Newfoundland website has loads of detailed information on all the stages of the rally, including gas stations on the transit legs, road closure information, start times and the like. But the coolest thing is that it's also bundled up into a Google Earth file so you can lay it out on your own pet planet. Select what you want to see, spin it around, do a fly-through or just marvel at the wind-swept ocean. Amazing. I'm going to spend a lot of time "driving" the rally now. It's science fiction come to life.
This is the "Upper Island Cove" stage on the last day.
entry 306 | | | 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 12, 2007 - Whoops.
The instrument lights haven't been working in the car and I've been driving it at night more than I ever expected. So I pulled the instrument cover off to see if someone might have cut the wires - and the 16-year-old plastic snapped. It's a common problem, the cover is held in place with three very strong clips. But all three of them went at once. I just threw out another one with the same problem. I guess I'll have to spring for a functioning cover, or find another fastening technique. Hmm.
I also started working on the VICS system. This controls a quartet of butterflies in the intake manifold, changing the volume of the manifold to improve low-end torque. It works amazingly well. But of course, the VICS actuator has a broken vacuum fitting. I could either try to glue it in, or modify a later VTCS actuator by shortening the shaft. And that's what I'm going to do, because I'd rather use a welder than glue!
entry 310 - tags: engine | | | September 14, 2007 - Martini paint codes.
Someone asked me via email for the paint codes for the Martini paint job, and I realized I'd never really spelled out the final mix. So here it is. I used NAPA Martin-Senour paint in the "Gold 5.0 urethane" single stage mix for the stripes and was very happy with how it laid down. The white was PPG Omni.
Dark blue. VW Marine Blue from a 1988 Golf. VW LA5B, M-S code 23427
Cyan. Mercedes DB5508, apparently. I used M-S 59392
Red. Opel Flame Red from a 1968 GT. Opel L512, M-S 20934
White. Mazda Crystal White from a 1990-93 Miata. Mazda UC, M-S 39783
entry 311 - tags: paint, Martini | | |  | 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 15, 2007 - Whoops!
The last time I was at the track, the car was pinging above 6500 rpm. We pulled out some timing, but it persisted. I think I might have found out why. Two of the bolts holding the cam gear in alignment slipped, and the intake was at full retard.
A walk down to the hardware store at the end of the street yielded some replacement bolts and the problem was fixed for just a few cents. The car should hit the dyno soon so I can get an idea of the correct timing (they were set at the equivalent of stock to start), and then I'll loctite them in place. These particular gears have spent a lot of time spinning fast on several cars and this is the first time we've lost a bolt, so hopefully it's an isolated incident. It's a good thing I have the cam cover cut, or this would have been hard to spot.
entry 313 - tags: engine | | |  | 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 | | |
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