A904 PISTON INSTALL HELP!

[FredS]

no,there should not be large air leaks on any piston on either the forward or direct. The metal rings on the reaction shaft do allow some air bleed, but not enough that the piston doesn't move up.
The outer seal on the direct drum you've been fighting is the seal that can roll when you push the piston into the drum.

 

[joshua dewitt]

the pistons are going up and applying the clutch plate, had to air pressure up to be 4 psi at blow gun. the piston is not escaping air out outer area, can hear the air in this inside area, im guessing reaction area and the pump outer big o ring has has coming from it. that is why I was asking if supposed to bleed though the pump some or not.

 

[FredS]

not between the pump halves, no.

 

[joshua dewitt]

then i have a pump problem that makes sense... will look into it thanks Fred S.

 

[joshua dewitt]

hey Fred s. I figured out the issue tonight, took all apart, air checked each piston with out clutches in with some trans fluid on top of piston, no bubbles, or air leaks, so they are seal ok, researched the pump, found that the 2 hales that go tighter had a spot of super mild clearance between them near the fluid ports, causing air to be escaping though the ends by the large pump outer O ring. took apart flat scuffed with 800 grit emery cloth, cleaned al out, reassembled torque to 175 inch lbs, and no major leak here, that was it, in the pump no excessive air leak now. THANKS FOR ALL YOUR HELP!!..... quick question what are the preferred clearances on the clutch pack for the forwards/rear clutch 4 pack, and the front/direct 5 clutch packs., looking for tight , mine in spec by book , but a bit to much travel for my taste...

 

[FredS]

I shoot for .032-.035 for the forward(4disk), and .065 for the Direct(5 clutch).

 

[fishy68]

hey Fred s. I figured out the issue tonight, took all apart, air checked each piston with out clutches in with some trans fluid on top of piston, no bubbles, or air leaks, so they are seal ok, researched the pump, found that the 2 hales that go tighter had a spot of super mild clearance between them near the fluid ports, causing air to be escaping though the ends by the large pump outer O ring. took apart flat scuffed with 800 grit emery cloth, cleaned al out, reassembled torque to 175 inch lbs, and no major leak here, that was it, in the pump no excessive air leak now.

I've ran into pump warpage causing the leak you described several times on 904's.