| MIATA BUILD |
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 | |  | March 30, 2008 - Autocross time!
The Corvette club was holding another autox, so I brought out the race car to see how the new suspension would sort out. Last time, I was hampered by the open differential but still posted a good time. Let's see how it works this time.
The lot was dusty and it was relatively cool, so it was a good test of the ability to put power down. Which turned out to be a challenge. Despite the Torsen diff, I was still getting wheelspin on the inside rear wheel exiting right turns. This is frustrating. It wasn't a problem on the track a few weeks back and it was only apparent on the tight confines of an autocross course, but still - I thought I had this licked. I'm going to do a little more poking around. Course workers confirm that the inside rear was simply unloaded and just spun up. A Torsen will go fully open when there's just no traction on one corner. I could throw in a preloaded Guru differential for the track day next weekend, or maybe I'll just let it stay as is so I can do a direct before/after comparison.
The first few runs showed that I had the ability to light up the rear tire(s) and slide the rear end around, but also that the car seemed to have some understeer in the few steady-state corners on the course. So I softened the front sway bar slightly to see if that sorted the problem. Yup, the car was much happier. It may be a little too biased towards oversteer now, but we'll find out next weekend on the kart track. Right now, it'll do exactly what I ask it to and can really be moved around on demand. Of course, that's with a maximum speed of 57 mph according to the rally computer. How will it do at 120?
I was also playing with the brake bias, thanks to the new pads. For a couple of runs, I had too much in the rear. The final braking zone took place in the middle of a big sweeper, so the car was unbalanced to begin with. On one run, I was countersteering fairly enthusiastically to keep the rear wheels behind me as the car wagged its tail into the corner. It worked, though, and a quick twist of the proportioning valve sorted that out. By the end of the day, I had the brakes dialed in pretty nicely and the car was mobile yet controllable under braking. Of course, I'll have to do it all over again once the new pads are installed.
So, how did it do? Well, there was an STi on sticky tires in attendance. Try as I might, I couldn't get within a half second of him. But Brandon and I were locked in a great battle. He has an extra 110 hp and Azenis tires, while I have the Toyo RA1s. It turned out to be an excellent match, going right down to the wire. The final margin was 0.079 seconds, with me being slightly faster. What a great race. I managed to come in second overall, which is not shabby at all. None of the Corvettes able to keep up with the three fiercely battling "metal cars". The fastest 'Vette was 1.8 seconds behind us.
Brandon, if you're going to strike a goofy pose for the picture, I'm going to take the picture!
entry 444 - tags: testing | | |  | 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 9, 2008 - Another video is up.
This one's a full lap of the track from behind the wheel. You can read more on the video page for this video.
Watch it!
entry 447 - tags: 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 - Traction pad!
Remember my attempt at a traction pad for my heels from last summer? It was a failure. That particular piece of non-skid was from Home Depot, intended for use on stairs, ladders and the like. I stopped in at a local skateboard shop a couple of weeks ago and picked up a chunk of deck tape to try again. And it works beautifully. It was on the car for the recent track day and it's still solidly mounted to the car - unlike the Home Depot stuff which came adrift almost immediately. At 20 cents per inch, it was also a whole lot cheaper than the Home Depot option. So a win overall then.
entry 450 - tags: ergonomics | | | 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 | | |  | April 21, 2008 - I finally got around to installing my mudflaps.
There's no real reason why it took me so long or why I'm just doing it now. They were provided by rallylights.com and are made of some indestructible material that's actually pretty easy to cut with a sharp blade.
entry 452 - tags: sponsors | | | 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 7, 2008 - I spent the weekend at the Walter Mitty historic races.
It was gratifying to meet so many people who were aware of the car!
One of the cars there was a 911 with Martini livery. I was glad to see that the stripe width varies slightly, just like it does on my car. It's part of the hand-painted character! Of course, this car had also been carefully sanded and clearcoated unlike mine, but I'm willing to accept that. However, it became obvious to me that I need larger Martini logos on the doors.
I've been considering how to get the car to Newfoundland for the race. The plan was to ship the car out and I'd fly to meet it. But this causes problems with spare parts, tools and tires. So now I'm thinking of driving out, towing the car on a trailer. It'll be a long, long drive (about 5 days) but it'll save a bit of money as well as let me carry more things with me. My friend Trevor is willing to ride along as a copilot. Ah, all the complexities of taking part in a big race...
entry 454 - tags: martini, logistics | | | May 14, 2008 - "Volume 2" of the 2008 Targa regulations came out this week.
I'm going to have to go through them all to make sure everything's correct. One change is that we apparently no longer need interior door panels, so there's one job off my list. We're also allowed to carry a space-saver spare, which I don't believe was the case before. That would make packaging a lot easier, but anyone who starts a stage with a space-saver mounted gets hit with some huge time penalties. I expect that's to keep the driver from trying to drive quickly, but it might be worth taking the weight penalty instead.
I also spent another 90 minutes on the phone with Expedia. That makes for a total of (I believe) 5.5 hours that I've spent on the phone with them, trying to deal with various problems associated with Janel's flight out to Newfoundland for the race. It's been frustrating to say the least. It's difficult to get someone from a small town in Colorado to a fairly remote part of Canada in the course of a day, and the airlines keep monkeying with the flights. Lots of frustration to put it mildly.
entry 455 - tags: logistics | | | May 14, 2008 - The Targa Miata website is now part of the Slow Car Fast family of websites.
Sounds very fancy, doesn't it? But really, it just means that I'm trying to get all of the various projects and sites gathered together. So just in case you're bored reading about this particular Miata, feel free to check out the other members of the fleet. You've seen them in the background of the photos, now's the chance to see them up close.
There's a new kid in the garage as well - a 1972 MGB GT. It's in the debugging stage right now, and it'll get a V8 after the Targa's over. It's Janel's "fun car", you see.
SlowCarFast.com
entry 456 - tags: announcements | | | May 21, 2008 - I pulled the hardtop off the car the other day.
Hey, it was hot outside! It's the first time it's been topless since the final stripes went on, actually. Naturally, I almost got caught in the rain. Serves me right. A coworker did comment on just how light the car feels down the road. Fair enough, it's about 300 lbs lighter than his!
I've shuffled the cars around in the garage so the Targa car is no longer trapped behind an MG waiting for shocks. So I can get the car out again. I need to focus my preparations on the upcoming TSD - with various non-car events happening most weekends these days, it takes a bit of planning to ensure I get the time I need to finish the work. And of course to figure out what work needs to be done!
I spent some time going through the new regulations and pulled out one or two things that need some attention. Nothing too major (hopefully), but it's good to have the confirmation.
One thing I did notice is that I have to give up the windshield banner to event sponsors. That's a shame, as I matched the look of that banner to the classic Martini look. I'm going to have to find some other place to put the Flyin' Miata logo as well. Hmm, the old Martini cars used to put logos on the roof...
entry 457 | | | May 22, 2008 - I got a Garmin nuvi GPS for my birthday.
No really, this is related to the Targa. I have it set up to give me directions when I'm driving around, mostly so I can get used to distances. Now when I'm told that a turn is coming up in 150 meters, I have a better idea of how far that is.
Or maybe that's simply my justification for playing with it.
entry 458 - tags: skills | | |  | May 25, 2008 - Here's an overhead shot of the interior.
Mostly because I have the roof off, so it's easy to take! But you can see the new net I installed on the transmission tunnel, to help Janel corral all of her paperwork. The size of the car is liable to be a bit of a problem when it comes time to actually take part in the rally, as we're going to have more stuff than places to put stuff. Especially helmets. But if people can do this in a Caterham, we'll figure it out.
entry 459 - tags: ergonomics | | |  | 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 - We have to carry three safety triangles with us in the car.
No problem, so I picked some up at NAPA. Holy cow, they're heavy! That black base is full of sand or lead or depleted uranium or something, designed to keep the triangle upright in a hurricane. I'm going to do some small modifications here to make them a little more svelte.
entry 461 - tags: safety | | |  | 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 7, 2008 - My friends Axel and Steffi from Germany dropped by for a visit, bringing their son Tom (almost six years old) and friend Andre along with them.
Both Axel and Andre are pretty familiar with the car and were quite eager to see it. Apparently it looks better in person than in the pictures! Anyhow, while they were here we had a fun day of driving all over the place in a bunch of the cars.
entry 463 | | |
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