AxeHealey GRM+ Memberand Dork
3/29/21 7:25 a.m.

While I was under the truck replacing the pan gasket, I noticed it was also clearly leaking from the shift rod. I've now replaced both the large seal and the o-ring. No matter how much I crank on the 7/8" nut on the inside of the trans, the whole assembly; two arms on the inside and everything on the outside of the case has about 1/16" of in and out movement. There doesn't seem to be any up/down, side/side movement just in and out. 


Is this how it's supposed to be or is this just going to leak like a sieve? 

APEowner GRM+ Memberand Dork
3/29/21 11:37 a.m.

It's been probably 10 years plus since I've been inside a C6 but it sounds like you may not have the internal arm seated on the shaft correctly.

AxeHealey GRM+ Memberand Dork
3/29/21 11:52 a.m.

In reply to APEowner :

Thanks. That's what I'm worried about. The arm and shaft only fit together one way and it's certainly not the easiest holding the arm in park and getting it lined up but it definitely *seemed* right from where I was laying.

It probably makes sense to take it back apart and check yet again...

AxeHealey GRM+ Memberand Dork
3/31/21 9:50 a.m.

I know I'm reaching here but just before I pull this thing apart again, does anyone else have thoughts?

Robbie (Forum Supporter)
Robbie (Forum Supporter) GRM+ Memberand MegaDork
3/31/21 9:55 a.m.

I have no c6 experience. But is this a case of the shaft getting worn down by the seal after thousands of shift cycles? Or is the seal installed backwards?

Only asking because I've done both of the above before on rear main seals...

Ranger50 UltimaDork
3/31/21 10:11 a.m.

There should be a rollpin that holds that arm in. The arm might be worn out.

AxeHealey GRM+ Memberand Dork
3/31/21 10:17 a.m.

In reply to Robbie (Forum Supporter) :

Well, the shaft definitely looked to be slightly worn down but the movement doesn't seem to be in the direction of the seal...if that makes any sense. Just sliding in and out of the trans case. That is, there doesn't seem to be any indication that the OD of the shaft and ID of the seal are out of range.

As for installing backwards. There's always a chance of that but I'm almost certain it is not. 

The face you can see of the large seal there is facing out from the trans. 


AxeHealey GRM+ Memberand Dork
3/31/21 10:19 a.m.

In reply to Ranger50 :

I didn't encounter a rollpin. At least I didn't have to deal with one while doing what I was doing so I guess I can't say.

Sorry the pic of the seal is so gigantic - I thought I adjusted it to 250.

AxeHealey GRM+ Memberand Dork
4/1/21 7:42 a.m.

Well, I pulled it back apart last night and when the arm is fully pressed against the outside of the transmission, about 1/16" of the shaft that comes through on the inside that isn't threaded. That's where the movement is coming from.

Maybe that means the big seal on the outside needs to be slightly proud of the surface but there's no changing that now. Trying to move it would destroy it. Only thing left to do is fill it with fluid and see how much it leaks. 

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