Synthetic lube and leather seals

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sledger46

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I have a leaking pinion seal and when I went to find a replacement They keep mentioning leather. Are leather seals compatible with synthetic gear lube? I use synthetic lube and wonder if it part of the cause of the leak in my 742, 8 3/4.
 
If that is an original seal, it has served you well, replace it. Synthetics drip out of even the best seals if they have run anything accept synthetic. If it is original, what were your thoughts pushing around an old seal like that? Don't mess with the success of a 40 year old seal.

Your best bet is to stick with the oil you started with fresh seals. If it was dyno oil, run dyno oil, if it was synthetic, run synthetic. Don't cross pollenate. Try draining it out, cleaning everything with carb cleaner and put dyno back in.

Good luck.
 
The seal was part of a complete rebuild of the rear end. After the rebuild it has only had synthetic lube.
 
I've never seen a leather pinion seal on an 8-3/4 and I've tore apart ones dated as old as 1966 that I'm sure were original. Who's telling you their made of leather?

Was the yoke checked good for wear? I've seen a few with a groove worn in them right where the seal rides and they won't seal up. Also saw them leak around the outer perimeter of the seal so I use a little shelac there when I install them. Haven't ran accross it but I've read that they can also leak out through the splines so guys use a little sealer on the splines.
 
I see that. O'Reilley's shows it to be leather too. I've bought many over the yrs. and never once saw one made of leather. The real old cars used leather seals but I believe they were pretty well all phased out by the 50's. I'd say just go with it no matter what the description says. If you have a 742 case the timken 7216 seal is correct for it. Let us know when you get it what it's made of. My bet is it'll be neoprene. BTW: I've used synthetic gear lube with no issues.

Hey I just noticed your location. I'm just 45 miles n.e. of St.Louis so were not real far apart. My Uncle worked at the Chrysler assy. plant from 1960 until he retired sometime around 1990 (I forget exactly when). What a lucky dog he was to get to see our iron being built and even got to drive some very rare Hemi cars.
 
...................Yes there was/is leather seals in 741 and742 cases from 1957 to 1968.........chicago rawhide made them............i've changed a few dozen............kim..........
 
oldkimmer said:
...................Yes there was/is leather seals in 741 and742 cases from 1957 to 1968.........chicago rawhide made them............i've changed a few dozen............kim..........
Click to expand...

They don't make replacements out of leather nowdays do they Kim? I have only bought Timken's and another brand (drawing a blank on the other brand) and they sure don't look like leather unless they'lve got some odd way of processing it to make it look like neoprene...
 
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