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Discussion Starter #1
Has anyone experienced sealing problems during an air pressure test between the 2 sealing rings on the stator support that seal the oil channel to the forward clutch in the clutch hub? I have a C4 on the bench that gradually lost all forward gears. I rebuilt the transmission about 2 years ago & everything with the air pressure test checked out fine. Now on disassembly the forward clutch is toast!!. Reverse/High clutches look brand new. I put the pump in a holding fixture & stacked both clutch drums on it. I blew compressed air into the respective holes in the pump for both clutches after squirting a syringe full of ATF into each hole & as I expected the rev/high clutch engaged with a thud but the forward clutch piston only moved very little accompanied by a hiss of air from the 2 sealing rings on the stator support. These are steel sealing rings & are brand new. I cannot source any teflon rings here in Germany & am wary of using them in a street application. I have built countless C4s & never had a sealing problem with steel rings in the past. If anyone has had this problem before (Greg) I would love to hear from you.
Cheers. Gaz
 

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Check the bore in the drum.
Remove the rings from the stator support and fit them in the drum.
They must fit snug and compress in the bore.
The ends of the rings should almost butt.

There is a small chance the bore in the drum is egg shaped.
Not common, but it does happen.
Make sure the bore is perfectly round.
 

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Discussion Starter #3
Thanks for taking the time to reply! I miced the bore with a 3 point micrometer, it was max 0.003 out of round which I think the sealing rings should compensate. I have the trans reassembled & in the car & it is holding up fine. Just a matter of time I guess.
 

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Somehow I missed this post, just saw it now . I've not had issues . There are two different width sealing rings , pre 78ish and after is wider . I'm guessing the widths were correct for the stator support?

I test fit every ring in its bore to check prior to assembly.

I did get a wrong ring in a kit a little while ago. Luckily my thorough prechecks I always do picked it up. It could of gone unnoticed

My rule is if using a valve body with modulated line pressure gets steel rings , constant pressure V/B gets teflons
 

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Thanks Greg. Yes I was aware that there are different width sealing rings. I always compare what I take out to what is going in & never throw anything away until the transmission is back in the car & running. Thanks for your answer. The trans is working fine fine now. Just see if it holds up permanently.
 
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