AW4 rebuild question

[96cherokee40]

Hey all,

I am in the process of rebuilding my AW4 and have finished installing all of the rotating assembly. Per the manual, I have applied air pressure to the feed holes to confirm piston movement/clutch engagement. All of the pistons can be heard engaging the clutch packs, but I can hear blowby during testing of the direct clutch and forward clutch. I realize the pressure is maintained via seal rings on the overdrive support (pages 63 and 94 of the AW4 manual give a decent breakdown of what I am talking about), but I imagine that those soft seals were not designed to hold back all of the pressure. The rings are new and I imagine they may grow once exposed to tranny fluid for a period of time, though I did coat them generously with petro jelly.

Is this blowby okay/expected as long as the pistons are engaging? I had to apply 90 PSI of air pressure to get the desired engagement. Does anybody even know what I am talking about?

Wes

 

[IH392]

Are those rings the split rings on the shaft. When I rebuilt my tranny, I remember air escaping too when appling some of the clutches. I don't remember which ones since it was a few years ago, but I don't think it was leaking a tremendous amount of air or anything, just a hissing sound is all i remember. Maybe you can put some tranny fluid in the oil passage and then apply air and see if that holds pressure better. I wouldn't worry too much if you know that the piston in the clutch doesn't leak air.

 

[96cherokee40]

Yes, those are the split rings. The pistons are definitely good too. I guess the only way to know for sure is to install it and see what happens. Hell, it's only 3 hours to take it back out again anyway. Thanks for the info, I really appreciate it.

P.S. How did your rebuild turn out? And did you change anything (adjust the pressure regulator, shim the accumulators, etc) while you were in there?

Wes

 

[IH392]

Rebuild turned out just fine, it shifted normal, maybe not as firm as I would have liked, but nothing strange. I didn't make any modifications to the tranny, since it was my first rebuild. But I remember the first/reverse clutch pack was worn out. Make sure to take a few a good pictures when you have the valve body split, I remember it was tricky to figuring out where all the check balls were supposed to go.

Good Luck!

 

[96cherokee40]

Ya I had a weak solenoid for a long time, causing my first/reverse pack to be just about gone. Some of the clutch discs had no material left on them! Thanks for the heads up.