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FB's on Oval's

Old 03-10-05, 05:39 PM
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FB's on Oval's

There's been some mention in various threads of people, past and present, who have had FB's (or maybe other RX-7's, I tend to be FB-ccentric ) on oval tracks. I don't really have a purpose for this thread, other than to attempt to collect a little information from those that have. Specifically, how on earth did you get positive camber on the LF? I just got back from running a customers "79" ITA-prepped car on the local 3/8's mile asphalt track (Thunderhill Raceway). The first time we hit the track it had a road-race setup on it through-and-through, except that we had 22PSI on the Left side tires, and 29 (I believe, I can't remember now) on the Rights. Tires are worn-***-out RS04's. We started off with ~2 or ~2.5 negative camber on the RF, roughly the same on the LF (which is the least camber we can get in it).

After the first stint, the tire temps were okay OK the back given the 3-link/panhard setup. Fronts were awful. Moved the RF almost all the way negative on the camber plate, and went out again. Car was much faster, I ran a best 18.45 (bear in mind with the first and second sessions combined I've run a total of 15 laps on the track.... ever). Moved the RF all the way negative and gave it another stab. Ran two 18.1's, an 18.19 and an 18.14 -- not bad, but still about a second and a half off the winning times. Since we're in a rotary, we're not interested in getting much below 17.5, since they'll throw us out so quick it'll make our heads spin.

Anyway, we got a baseline on the car and believe we've figured out what we need to break into the mid-17's, the problem is achieving it. The car has coilovers on the fronts, and with the camber plates like they are we really could use a little more camber in the RF, and we could use a lot less negative or some positive in the LF. When I came in the last session, the highest temperature on the tire was about 5 over ambient, and our suspension guru said the LF was pretty much in the air. Since it's in the air most of the time, having less negative camber (or positive) would mean that when the tire does touch the ground it'll help us rather than hurt us.

Enough of my incessant ramblings, let's hear from you guys oval tracking RX-7's. Any tips and tricks appreciated, but bear in mind this thing needs to stay SCCA ITA/7 legal for the moment.
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Old 03-10-05, 07:58 PM
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good thing I can remember this product.

http://www.racingbeat.com/resultset....rtNumber=14006

maybe between that and the upper adjustment you can acheieve something more bearable on the LF. On thing you have to bear in mind is that the front track of the car will now be skinnier than the rear. Not sure how that would affect car. To offset the skinnier front you could run a high backspaced wheel. That being said I have no oval track exeperience just trying to relate what would seem common sense.

those LCA should still be legal I think as well in SCCA. (check rules first though)
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Old 03-11-05, 10:44 AM
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The above part wouldn't be legal in IT, but wouldn't be that hard to change out with a stock part.

As far as the Positive Camber on the left... is your camber plate bolted on? Maybe as simple as turning it 180 and slotting the tower a little more? Dunno... but thumbs up on racing the RX as much as you can!!!!
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Old 03-11-05, 12:30 PM
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Yes, camber plate is a bolt-in. I'll have to see about flipping it, geometry isn't my strong suit and trying to think of what it'll do in my head doesn't work!

Whatever I end up doing I'll be sure to post here in case anybody else is wondering.


The car never even got off the trailer... it's getting ready to go to TWS for a restricted regional this weekend, and it's still got it's oval setup on it. I wish I was driving it this weekend, it's a pretty fun car.
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Old 03-12-05, 06:33 AM
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Originally Posted by Speed Raycer

As far as the Positive Camber on the left... is your camber plate bolted on? Maybe as simple as turning it 180 and slotting the tower a little more? Dunno... but thumbs up on racing the RX as much as you can!!!!
Thats exactly what I was going to suggest. I think youll get more that way. Also since your using old tires, look for some tires that will allow you to get some stagger. More banking= more stagger from what I understand. Which reminds me, is this a high banked, or flat track? Ive never circle track raced, but have crewed for some teams (National tour Legends cars) . Circle track magazine has lots of great tech. check their website for some tech articles. Youd be surprised how similar most oval track cars are to the 1st gens suspension wise. Being left side biased makes our cars good circle track cars. Get more weight shifted to the left if you can. I assume you have different springs for the car? Maybe a stiffer right rear spring will help plant that left front tire. Or jack the right rear up with a spacer for more left front crossweight.
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Old 03-13-05, 05:27 PM
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Yeah, I'm familiar with the basics of circle track setups... ran Quarter Midgets for 8 years. Unfortunately, the series specs same-size tires, and we can either use theirs or our trusty old S04's. They also have a weight-bias rule, going from memory a tub car can have 58%, where tubeframe can only have 54%, so we're limited there. Unfortunately, their scales weren't working when we were there, so hopefully they are when we go back.

The track is an interesting configuration: D-shaped and relatively highbanked. From the stands it looks pretty flat, but driving it it's the most banking I've ever been on. I honestly think if I had new tires I wouldn't have to brake but to set the car for the next straight, so it's pretty banked. If I drive the car in the next test I'll put a cam in the car and post video.

While waiting between sessions I crawled around under the car this weekend, and I think my best bet is to drill new holes for the camber plate and slot the tower for the shocktop. I'll try flipping the plate before I do that.

Also discovered that on the TWS 1.8cw track we need less camber on the inside (pass. side) wheel, so I may end up redrilling both towers.

Oh - and the suspension guru we had working with us is a big fan of soft suspension on ovals, and his reasons/methods are pretty clear. The guy that's won all the marbles in the series we're going to be running is a pretty good exampe: he was running a 2002 and had the thing sprung like a roadrace car (he's an old SCCA man, too). As soon as he put softer springs on the car he quit snap spinning and started running off the leaving the field.

Too bad they won't let me put a 1.6L Miata engine in a car, or I'd be building a new racecar in a second!
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Old 03-15-05, 06:54 PM
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i did 3 ovals last year and ran my road race setup no problems at all


rob

ooops it was an fc
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