I have a 99 f-150 with the 5.4 and 4r70w with 120,000. rebuilding the engine and the tranny has been acting up, shifting hard from 1st to 2nd and again when in downshifts to pass, so will see about it while it is down. i want to go with cams, headers electric fan and procharder when it all comes together. any advice on how to prepare the tranny for the increase in hp while i am in the process. thanks..

 

The 4R70W is actually a very good transmission. When it comes to high torque, the weakest point is the intermediate shaft. I've seen a few of them break so if you're rebuilding, you'll want to upgrade. Other than that: You'll also want to add a shift kit or performance valve body and keep the heat down with an additional cooler.

 

i bet you money you broke the 1-2 shift accumulator spring, i have seen this happen a few times, mine did it and so has a few other peoples i know. its a cheap fix.

 

silver bullit99

is there an easy way to check the spring so i don't have to rebuild the tranny. it still pulls excelent but a spring could save me some jack!! or should i just overhaul and upgrade anyway?

AJ

I already have a tranny cooler do i need another one or a larger one?

 

Remove the trans pan and you can see the 1-2 accumulator piston, it is held in place by a snap ring, remove the snap ring and the piston can be slid out, the springs are in there.

 

i checked the springs and they look fine any other suggestions??