| MIATA BUILD |
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 | | 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 | | |  | June 7, 2008 - Of course, while they were here we had to visit the track.
And Tom jumped into the passenger's seat to take a few laps with me. He speaks German and Portuguese, I speak English and French. But a big grin comes across pretty well regardless!
So, how did the car do? Well, it handled everything with aplomb except for the track sessions. I took the car out first and soon discovered that it could not hold any coolant and overheated badly. After it cooled off, I pulled the radiator cap off and discovered that it was in terrible shape. I wonder if it was a temporary one from a junk car that I put in place while building? Anyhow, it's going to have to be replaced.
We stole the cap off Janel's car and went out again. Still a problem, possibly due to air bubbles after a big coolant blow-off with the bad cap. But the radiator did come out of an older car, so I'll pull it and clean it.
This track is excellent for testing cooling systems. It's at high altitude, has low humidity and has low average speeds - it's a worst-case scenario for cooling. The high was also getting pretty close to 90F. So if the car's ever going to have cooling problems, this is where. We were also running longer sessions than usual here. I don't anticipate cooling to be a major problem in Newfoundland, but if I can keep the car happy here after 15 miles of full throttle in second gear, I'll never have to worry about it.
Otherwise, the car did pretty well. It was at the track along with The Seven, which does have the tendency to make anything feel a little fat and slow. The Targa car has a very different handling balance because it's built for a different purpose. It's less prone to oversteer (no, really!) and more forgiving - as it has to be. But I think some of the things I learned building the Miata will get transferred to the Seven, just as the knowledge from the Seven helped me build the Miata.
entry 464 - tags: testing | | |  | June 7, 2008 - At the end of a long day of driving.
We bolted the hardtop back on, I did a few checks of the car and it was time to get to bed. The Glenwood Springs Rally put on by the MG club was in the morning!
entry 465 | | |  | June 7, 2008 - At the crack of dawn, Janel and I took off for Glenwood Springs to try our hands at a TSD (Time-Speed-Distance) rally.
There's actually a TSD aspect to the Targa in the Grand Touring class, but we're not running that. Still, we figured the experience would be a good one, allowing us to spend some time in an organized rally environment that's fairly low pressure. And with cool cars. There were at least 60, including two or three other (stock) Miatas and a newer Corvette. Pretty much everything else was a classic.
Let me tell you, rolling up into a parking lot full of vintage cars in a stickered-up and Martini-liveried car with a full rally computer, well-broken in race rubber and your names on the roof makes you feel a little conspicuous. And people certainly don't believe you're novices!
entry 466 - tags: testing, skills | | |  | June 7, 2008 - Janel, hard at work watching for instructions.
A TSD is more of a treasure hunt than the Targa is, and there wasn't as much navigation as we would have preferred. They have to be run in rural areas, though, and rural in Colorado means you don't get a lot of turn-offs because you're usually running along a valley or climbing a pass. Still, we did get much more familiar with communicating with each other, dealing with problems ("I said slow down!" "But it's sooo boring!") and Janel got to spend lots of quality time with the trip computer.
All joking aside, despite the warnings of others never to do a TSD with a loved one, we had no compatibility problems. Both of us were in pretty good spirits throughout the day. This was probably in large part due to our rally computer. See, the required average speed varied fairly frequently thoughout the stages. But for us, we set the Coralba to display the average speed and simply reset the tripmeter at each change. So I could simply look at the display and see that I was 0.1 mph high, or we could stop and wait until our speed dropped to the ideal level. Normally there would be much work with stopwatches and calculators along with a lot of stress. Our biggest problem was my apparent inability to drive very very slowly at times. We didn't get lost, though. That's the important thing. And any frustration was tempered with humor instead of anger.
We also learned quite a bit about the car. It turned out to be an excellent shakedown test as we'd never spent 12 continuous hours in the car before. First off, both Janel and I found we need more padding in the seats. My memory foam must not be thick enough. Our butts were asleep before we even got to the start line, over an hour from our house. Also, the car is hot and noisy on the highway and cracking the windows seems to draw in exhaust fumes through a number of small holes in the transmission tunnel. The latter is easy to fix. Hot, well, that's probably not going to be a big concern in Newfoundland. Noisy - it's time to look for some transit headsets. We won't be at a sustained 80 mph on the transits, but even the background nose at 40 would get tiring over the course of the day. I'm going to throw some light sound deadening at the back of the car to see if I can help this at all. I think I'm also going to go to a 4.10 rear end instead of my current 4.30, as I don't need such short gearing.
Mechanically, the car was faultless. Some sadistic organizer put a 20-minute stop in at Leadville. That's about 10,000' up, and you should have heard the poor carburetted British cars trying to struggle back to life. Let's hear it for fuel injection!
Okay, almost faultless. The suspension got a nice dirt bath after we spent about half an hour trying to maintain 38 mph on a fairly rough road, and it's creaking badly. I think I just need some bushing lubrication underneath.
A long day, but a good day.
entry 467 - tags: skills, testing, ergonomics, computer, seats | | |  | June 7, 2008 - The holy grail!
A competitor from previous Targas lent us a copy of his route book from 2007. It's day 3, and it's marked up by his navigator both before and after the event. This page is the infamous wooden bridge.
This is fantastic. I have in-car footage of the entire event. Now we'll be able to compare it to the book to get a better idea of how the book corresponds to the new world. It's 2006 video and the 2007 notes, but it's close enough. I can't wait to see how some of the notes in the Greenspond stage correspond to the roads. It looks tough!
There are also the times for the various stages included. For those who have asked me why I didn't go turbo - I'd have to go faster. For example, on the Musgrave Harbour stage, I have to complete the course in 3:18 with an average speed of 110.4 kmh to avoid penalties. The aftermarket turbo Miata would have to do it in 3:07 or 116.9 kmh. That's a significant enough difference. If I'd built a 1990 Miata instead of a 1994, I'd have 3:22 to complete. But then I'd be stuck with about 400cc less engine displacement (have to keep the original block) and a weaker, less effective rear end. So I think I'm pretty good there.
There's a schedule of the day included as well. Looks like our 12-hour day today might have been good practice. Ugh.
entry 468 - tags: skills | | |
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