I have a 97 F150 4x4 with a 4r70w and 4.6. I rebuilt the tranny with new seals, clutches and electronics. Before rebuild, it would go in reverse, but nothing forward. I rebuilt it front to back and reinstalled. Poured in fluid and got the right level. Goes in reverse fine, but feels like it slips (or just needs high RPM to move) in 2h and 4h. I put it in 4l and it feels like it engages firmly. Any ides on what it might be? Is it a stuck valve in valve body or something in the Transfer Case????

 

Have you checked the fluid level after warming it up and driving it a bit?

 

I did check fluid after it ran a while. There was no "driving it a bit" with little to no forward movement with high revs. It engages firm in reverse and seems to do the same in 4lo, but high revs in 2h and 4h.

 

Not getting any hits, but made a small discovery talking to a tranny man. He said that I may have been sold the wrong EPC, have a valve stuck in the valve body or possibly cut the lip seal on the forward clutch piston. I don't think option three is it. I was very careful putting the seal in. I didn't take the valve body apart, so I'm actually hoping that to be the case. The easiest would be the EPC, but we'll see.

 

I don't know if it applies to the 97 but I remember someone on the forum talking about little plastic ***** in the valve body melting and needed to be replaced.

 

Roger that. That's what i'm thinking. I've got to drop the pan and pull the valve body tonight.

 

Remember i'm not the tranny expert. Just love to tinker and problem solve and the learning curve is rather tough sometimes. I pulled the valve body, cleaned and put new check ***** in. NO GO! I then pulled the tranny, which is a lot of fun with the transfer case exhaust etc. I pulled the pump and forward clutch pack/drum. TO my amazement, i had failed to change the seals in the forward clutch piston. BTW, those seals were the only two damaged. i did it in stages and had compressed the spring and removed it, but never pulled piston. Call me brain dead if you must. It was a hard lesson to learn. Anyway, i had to order new forward clutches since the new ones i had previously put in slipped and burned. LESSON LEARNED!