ATCWIZ

Hello- I have a 97 C5 that I ran in a few autocrosses and loved it. It is an automatic. I am missing a quarter of my left foot and while I can drive a stick, it is not the most fun for me in traffic and is sometimes painful.

That said, I blew up the transmission 3 times in 4 events. The transmission shop warrantied it the first time, but the second time they warrantied it, they told me not to bring it back again. I stopped autocrossing it after that. Each time it was the clutch pack that destroyed itself.

I took the car on a trip to AZ this last weekend and it was 105+ outside the whole time. The interesting thing that I noticed was that the car got really hot, really fast while driving in town. On the freeway, the car stayed at about 226. In town, I saw 243. Then it dawned on me. The car has a stall converter in it and is kind of 'sloppy' below 42mph. Could it be that the extra slippage from the non stock converter is creating extra heat and that, combined with my keeping the car in first and banging it off the rev limiter a few times, is what ate the transmission? Could this be remedied by installing a stock converter and an auxillary trans fluid cooler? (And possibly driving in second gear?)

I know some of you have raced the autos before and I would love to get back into the autocrossing as it is a blast. Any suggestions would be appreciated. The wife is on board with me either putting a stock converter back in the C5, trading it in on a C6 Grand Sport, or buying a cheaper, dedicated autocross car that has a manual but doesn't really see daily driver duties.

Any input would be appreciated. Thanks so much.

l98tpi

There is a problem with the builder of the trans if it only last a couple of autox's. If you want to continue to use the car, look into a trans from RPM Transmission and you may wan to look into a full manual valve body.

If you want to purchase a great manual car for autox, you can buy my 96 LT4 6spd



https://www.corvetteforum.com/forums...-on-black.html

Solofast

A "loose" converter is a horrible thing for autocross, been there, done that.. It didn't work worth a darn.. Changed back to a "tighter" converter and the car was a lot more driveable. With a loose converter not only do you generate tons of heat, but you can't "point" the nose of the car with a lift of the throttle. This is giving up a really important tool that you have to increase the grip at the front of the car.

That said, it shouldn't fail just because you revved it up. Most likely the clutch plates were junk aftermarket stuff and that is what failed.

froggy47

Agree with both guys, autox should not kill an auto tranny, get a new tranny guy. If you are going to autox a c5/6 with auto tranny get it "tuned" for quicker shifts if allowed by rules. My friend has a c6 auto with a tune. His accel foot is "damaged" by an accident. The stock c5/6 auto tranny shifts like a "slush box" but can be fixed.

Rookieracer

Talk to the guys at RPM Transmission. It wont be cheap.

I had them build an auto trans and lockup converter with stall for one of my C5s for autocross and road racing. The key was an auxillary switch I could use to lock the converter any time I wanted.

The need for an auxillary tranny cooler can not be over stated. Do it!
Stock vehicles with mild upgrades will run the tranny temps near the limit just driving around in hot weather.
There are lots of threads in C5 tech section about trans coolers.

Nokones

I ran a 700R4 built by Art Carr in my 90 1LE Camaro. The torque converter was a custom built 10" by Art Carr. Art designed the torque converter to keep the RPMs in the torque band. The torque converter design has to be designed for your cam, where you want to run the engine most of the time insofar as torque, etc., and the rear gear ratio. Yes, you will need a tranny cooler.

If the torque converter is designed properly, you will be surprised on the torque gained for coming off the turns at an autocross. It will almost feel like a 383 stroker motor.

Do not buy an off the shelf torque converter. They are not the right setup for autocrossing. It has to be custom designed by someone you knows how to custom build one.

Also, the tranny will need to have a good set of clutches that will withstand the extra amplification of torque and the valve body will need to be tweeked accordingly. The only way to do that is on a tranny dyno. If the shop/builder does not have a tranny dyno, go somewhere else.

ATCWIZ

Thanks for all the input guys. I found a shop in Poway that I am going to go and talk to that said they would warranty the trans while autocrossing. They said that if I break it they will keep building it until I stop breaking it. Interestingly I talked to RPM transmissions and they said that they could not build me a trans for autocross as the slow speeds and low airflow would kill the trans quickly. They can do drag transmissions all day long, but wanted no part of an autocross trans. I'm assuming that I will need a Sonnax input drum and some serious clutches along with a very serious trans cooler, but I think that I might be able to make something work.

Any thoughts on a transmission pan like this:http://derale.com/products/transmiss...fitting-detail Kind of an interesting product.

Any thoughts as to where to put a trans cooler? I am thinking something like this:http://derale.com/products/fluid-coo...ing-pan-detail mounted somewhere in the rear of the car so it isn't fighting for incoming air in the front and just cut the radiator completely out of the equation.

Thanks in advance for the help!

johnny c

i autocross the snot out of my auto. just stab it in second, and never shift.

ATCWIZ

Do you still have stock gearing? Stock converter?

Thanks

johnny c

yep, stock everything.