ok guys im fairly new to this and i was wondering about the strenth of the fd transmisions?

I used the search and got no where with that.

Basicly what im wonder about is a high horsepower, hi torque situation. How well do they hold up?

 

auto tranny are only good up to around 300hp. 5 speed seems to be able to handle high 400s and even in the 500s. above 500hp, im not sure. jason who owns rx7store.net has 500+hp in his 7. not sure if his tranny is stock or not. but at that kind of hp im sure it puts some serious strain on the tranny, not sure how long it will last at those #'s.

 

the tranny is strong enough to hold 400+Ib-ft tq. all u need is a new clutch.

 

you can get REALLY high HP numbers with the stock tranny. I know forcefed7(Ray Wilson from PFS) ran 9.4's with the stock tranny.

 

Just to throw another reply in here...

The stock trans will hold quite a lot of power. There are tons of people with 300+ ft*lbs of torque at the rear wheels and they don't break them. There are several people running more than 400 ft*lbs at the wheels and I haven't heard of any problems from them either.

You WILL need to upgrade the clutch and pressure plate for the higher numbers. If you are a drag racer, your weak spot will probably be the differential first.

Brian

 

Hard high rpm launching is what kills the trans. If your not launching the car you can run 550+ rwhp

STEPHEN

 

Ari at RP runs the stock trans and ran consistant 9.5's and better. The weak point in the trans is the output shaft. Right before the shoulder on the shaft where it tapers down to the splines for the drive shaft is where he breaks them. He has them heat treated or cryoed to handle the power. FWIW however, I broke mine last year at the shoulder at 16psi(about 385whp or 321f/lb) With ET streets and 7500rpm launches. I think mine was due to annealing however, since I had the shop rebuild the tranny 2 weeks prior. when I picked up the pieces of the broken o/p shaft it was a clean break and was blued for about 3 inches on either side of the rear carrier bearing support.( speculate the shop heated the old bearing with a torch to get it off the shaft).
Art

 

Actually I wonder if the thermal stress of heating caused some microcracking that quickly fatigued through. It usually takes hours for annealing to happen and will make the metal less likely to break clean. Got any pics of the crack face? (Curious engineering geek thoughts)

Dave

 

i have broken 3 trannies with my old car. one fresh rebuilt trans lasted 2 hours. you name i have it broken it.

ari is now running a guru dogmission in his FD that is why he is goings 9's and not breaking it

if you don't do hard launches you won't kill the trans or diff like SPO said.

my good friend ihor did blow a torsen diff shifting into 2nd hard when were messing around at a street light though haha