I have just re-assembled my 904 and pressure checked all the servos and clutch packs.

I can hear the clutch pistons engaging but I can also hear air leaking. I can hear this when I test front and rear clutch packs as well as front and rear servos. Is this normal?

I am using 30psi air pressure.

I am testing with the trans sitting upright on the bellhousing. When I apply air to the rear clutch apply case port, the whole output shaft assembly moves up by about 2-3mm.

Cheers
K12

sounds about right; they say to use even less PSI to air test than that; I forget the actual test PSI spec; you will see movenent in there, and if you apply TOO much PSI even a bad drum seal will appear good; on a smaller scale, kind of like the inner bead blast on a tire mount machine. You know, it ain't seated yet but all that extra "back" pressure seats it. Even with a bad seal, you apply enuf air, and youll still apply the clutch. having the trans standing up on its nose should have no bearing on air testing, vs having it laying on its back.