904 Tranny not shifting in drive

[bhthomas83]

A buddy of mine and I built a 904 tranny for my dart. It will manual shift thru the gears fine but when put in drive it goes into third gear and stays in third. It won't even downshift out of it. Have tried two valve bodies in it and does the same thing. Anyone have any ideas what it could be? My buddy thinks there may be a crack in the front piston assembly.
Thanks for reading.

 

[70aarcuda]

kickdown linkage or throttle pressure linkage adjusted properly...?

if installed...remove the linkage at the carb...drive around block and see if the trans upshifs ...it will shift thru the gears really fast....if it goes into high...that is or was your problem

 

[bhthomas83]

Everything was adjusted per instructions. I have a Lokar kickdown cable I'll remove that and see what happens.

 

[fishy68]

I can't imagine a cracked piston in the front clutch would cause that cause if it were cracked it would not apply meaning you'd have no third gear or reverse. The front clutch has to be applied or it would not have high gear in any gear selector position. It sounds like a governor issue to me. I'd run a governor pressure test to see what it is. If it's too high it will start off in third gear but manual shifting will operate correctly. The pressure should drop to near zero (no more than 1-1/2 psi) in drive at idle with the brakes applied (not moving) and increase as the car takes off. I don't remember the governor pressures off the top of my head but it doesn't take a lot of pressure to make it go into high gear. The governor test port is the 1/8" port near the bottom of the extension housing. I have a picture of it but for some odd reason it won't attach. If you'd like a picture PM me with your e-mail address and I'll send it to you.

 

[FredS]

fishy, it's it 1psi/1mph? I'd have to agree, sounds like a stuck governor. If its at max pressure, it won't downshift out of 3rd.

 

[bhthomas83]

Fishy was correct. We had a brain fart and put governor weight in backwards so pressure was 40 psi in drive with foot on brake.