argonaut

I just picked up a 99 FRC for my new Track car. I'm moving from a 07 Mustang GT to this one. The kid I bought it off had a very tall rear gear ratio installed, something like 2:73 (?). God only knows why because it totally sucks. So...I'm going to change it and would like some advice.

First question - what is your recommendation for the rear ratio? Although the car will remain street legal, its primary purpose is HPDEs and small number of AutoX. It has the T-56 tranny and (have to get it on a dyno) I'm guessing its in the upper 300's for power (headers, heads, cam). My home tracks are Summit Point, Pocono and I went to NJMSP once last summer, probably a few times this summer.

2nd question - how difficult of an install is this? Approx cost for parts and labor? Note: With the Mustang's live axle, its a pretty simple process to put in a new Ring and Pinion, costs about $500 for parts and labor. I have no idea with this car.

Any advice would be much appreciated. Here is a low quality picture of the car:

AU N EGL

3.42 is what came with your car. That is about the best gear ratio for road racing. Some guys have use 3.73s or 3.90s and 4.10s dictated by race rules.\

But for HPDEs 3.42s

V8 Juice

Tom is as always right on. I had an '06 A6 with a 2.56 stock rear axle and found it slow to wind out from a corner and switched to 3.42 and wow, what a difference. Any higher would have likely been too prone to break away on tight corner exit. Then came Road America....

95jersey

I agree 3:42 is best. Unlike your Mustang which comes with lame gears out of the factory, the Corvette is ready to roll completely stock and that is the beauty of the car. Everything was thought out pretty well on the C5/6.

sperkins

That's the weirdest thing I've heard in a while. Odds are that one of the previous owners changed the entire diff out from an auto car instead of just the gears.

racerwannabe

best idea would be to send me 750.00 and i'll send you the 3:42 diff i just took out of a '01 zo6

Johnny
life is good

argonaut

OK, thanks for the responses - sounds like 3:42 is the way to go.

What about my second question - any ideas what it costs to just have new gears put in the current Diff...or is it cheaper/better just to get a new Diff altogether?

racerwannabe

check with zip or rippie or the local mechanic buddy...i paid 300 or so for the gears and couple hundred to get it set up...then about a grand is the going rate to put it in the car..unless you do it youself...i bought a lift and have more than paid for it saving labor costs...or you can just pay zip or ecklers 1500 for a fresh unit....then ya still have to install it...
Johnny
life is good

ryan0

solid rebuilds are a little over 1k.

AU N EGL

do the rebuild and have them ( RPM or RockLand Standard ) put in some hardened race ready gears.

davidfarmer

I agree that with stock revs, 3.42 is good. You will mostly use 3rd and 4th, but can use 2nd in really slow corners. I'd pick up a used complete assembly and just swap the whole thing..........

varkwso

But the gears felt good

mountainbiker2

For most autocrosses you will need a 3.90 gear.

Steve