Leak at pinion splines

-

my68barracuda

Well-Known Member
Joined
Dec 6, 2009
Messages
2,616
Reaction score
2,606
Location
Indianapolis IN
Hello
I recently installed a Dr Diff 3:55 gear set into the 742 carrier in the 68 Barracuda.
Noticed a re occurring teaspoon size puddle of oil on the garage floor.
Last evening I put the rear end up on jack stands to investigate.
From the circular oil spray on the under body the leak is definitely at the pinion seal end.

Removed the retaining bolt and with light hand pressure was able to pull the yoke from the pinion shaft. Noticed that the inner seal of the pinion seal and the OD of the pinion seal from 9:00 to 3:00 was absolutely dry.

Took the same yoke and attempted to seat it on the OE pinion that I had removed from the differential. It would only partially engage. That same yoke easily fully engages on to the new Dr Diff pinion.

It is apparent that the oil leak is due to the loose fit of the pinion splines to the yoke with the new gear set. I contacted Dr Diff and he recommended putting RTV on the splines make a seal.

I had previously did some internet research and I found that fix mentioned in a couple of other forums. GM and Jeep stuff.

Does anyone else here have experience with using RTV to seal the pinion splines?
I am thinking it would be best to coat the splines in the yoke with RTV then press it on so the RTV gets squeezed out. Putting the RTV on the pinion shaft splines would extrude the excess RTV into the differential, I think.

thoughts on this?
 
I've done it before. I don't like it. I did it. It worked.
 
Only harm is that removing the yoke may be more difficult. Put the rtv on the last 1/2" or so
 
I don't understand why they ALL don't leak if the splines are not sealed.................
 
Shouldnt be an issue at all putting a little sealant on it. I wouldnt put it on the splines, just remove the nut and put a fair amount there and reinstall the nut.
 
It’s common to have to put rtv in the yoke or on the pinion splines. But removing the nut from the pinion isn’t. Did u mention that to Cass? U need 210-250 foot pounds torque on the pinion nut. Kim
 
It’s common to have to put rtv in the yoke or on the pinion splines. But removing the nut from the pinion isn’t. Did u mention that to Cass? U need 210-250 foot pounds torque on the pinion nut. Kim
I did mention the nut torque to Cass. He was adamant that Mopar was wrong on the torque for the 10 spline 742 cases. Cass says the correct pinion nut torque on a 742 case is 175 ft lbs.
 
The 742 case seal is different than the 741 and 489. If u took the nut off as easily as what I said there is no way it was torqued to 175 ft lbs. kim
 
-
Back
Top