ridedk4us

how much power can the 40R70W(auto trans)handle before i need to upgrade my transmission?

Aereon

our tranny's can take a beating if setup right.. and whether or not it craps out "depends on different factors. Abuse is abuse no matter if you are pushing 200hp or 400hp. So if you are a very agressive driver or drag race every weekend, you could have issues. If you are driver that drives normal most of the time and every once in a while has some fun with the throttle you can be alright."

A Jmod and a tranny cooler will help your tranny last longer.

sfi

Aeron is right. Most of it depnends on your driving habits. I asked the same question when I put my supercharger in last month. The shop said I should be fine at 366 rwhp, but eventually It will break. He said one of his clients had a stock auto tranny and had 551 rwhp ??? So I guess its a crapshoot. I always talk to Ford racing about this and I always get bull**** answer. They telll me its good for 300 hp to the flywheel ????? When you break it , replace it, because it may just hold out and $2000 is allot of money to wast on a new built tranny.