:scratch:

 

This 5 speed auto is the same as any auto I've ever used in hidh performance cars, none of them were built for real power increases much over what the car came with. Only exception is my 70 Chevelle SS 454, it came with a TH400 and is was built at the factory to take a bit more than the stock 400HP. My 62 Corvette came with a 2 speed powerglide but would blow it if you put more power to it than stock, however I had it built, including input-shaft and it could handle 1000HP, I don't have that but the transmission is that strong.

I spoke with Len at Lentech and he says the input-shaft is the weakest link, and they are making a new one. Sounds like it will not take much to beef-up this tranny to take more power, Whipple also mentioned the shaft to me.

Every tranny I've built up had the shaft replaced as this seems to be a week
point in all stock ones. Have to wait and see after we replace some parts in these how they hold together, but thats what hot rodding is all about!

Jim

 

its more about the transmissions design than anything, look at an exploded view of the trans you will see its weak links


and its not how much hp it will hold, its the torque that is the problem, and the weight of the car

 

You are correct, torque (and vehicle weight) is what matters, not HP.

An engineer who worked on the 5R55 trannie design said that he would not put more than 350 lb ft into a 5R55.

The 55, 70, etc # on a Ford trannie represents how much torque the trannie is rated to handle. So by the model #s a 5R55 is rated to take only 79% of the torque that a 4W70 can.

It's a problem, the trannie design guys were given the job to make a 5 speed trannie that was the smaller & lighter then the old 4 speed. The only way you do that is make the guts less robust.

 

Don't worry. With the suitable application of money and time, all those weak factory parts can be replaced by almost unbreakable aftermarket parts made of materials that would have the factory engineers crying in there beer (because THEY can't use that stuff!).

 

You are correct, torque (and vehicle weight) is what matters, not HP.

An engineer who worked on the 5R55 trannie design said that he would not put more than 350 lb ft into a 5R55.

The 55, 70, etc # on a Ford trannie represents how much torque the trannie is rated to handle. So by the model #s a 5R55 is rated to take only 79% of the torque that a 4W70 can.

It's a problem, the trannie design guys were given the job to make a 5 speed trannie that was the smaller & lighter then the old 4 speed. The only way you do that is make the guts less robust.
[/b][/quote]


His a article about the Chief Engineer for the 5R55S, may surprise you.

When I spoke with Len his may concern was the input-shaft, seems to think the transmission will be OK after that, at least thats all he said about the week link. That is the component that takes the torque. Have to wait and see after that what if anything is needed. The internals look pretty strong to me.

 

Sorry here's the link: http://www.designnews.com/article/CA380725.html

 

:bang: Whatta ya expect .... it's French. Not exactly known for power OR quality; only their w(h)ine.

 

LOL....you guys crack me up - thanks I needed the humor today!! :worship: :worship:

 

Fill in the blank

With French __________handling power will always be a problem we will have to fix.

a) Transmission
B) Government
c) Tires
d) All of the above