1978 Chevrolet Camaro - Diff seal leak

Front differential seal leaking

Is the pinion seal on the rear differential leaking or do you have a four wheel drive Camaro?

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Rear differential only…

Replace the pinion seal, while doing so inspect the yoke for damage in the seal area and check for metal particles in the seal. Metal particles from a failing pinion bear can get into the pinion seal and cause it to leak.

my 79 has 1:2.41 gears. oof. bonneville gears. i bet yours are close. pulling the pinion is no fun.

You must mean the FRONT SEAL on the differential. All Camaros were rear wheel drive only!

I believe that every GM 10 & 12 bolt axle pinion seal that I replaced was the result of pinion bearing failure.


Replacing the pinion seal is a matter of dropping the shaft and loosening the big nut on the pinion. Its not like you need to tear apart the diff to do the job… however if I recall correctly, there is a modern problem with this seal replacement and it has to do with the availability of the correct seal. Mr. @Rod_Knox also mentions a great source of seal failure that you need to look into…as any new seal will be destroyed by a failed or failing pinion bearing…so you need to be sure about its health.

This video will tell you what you need to know. If it weren’t for this seal availability issue…you could simply swap the seal and be done with it… This seal availability (and bearing health or lack thereof) might actually be why you need to address a leak in your diff to begin with. Watch the video…bout all you need to know.

Heh heh. Just like a wax ring for a toilet flange. Buy two of them because sometime one is not enough. Reminded me. Prolly 20 years ago I was in the Walmart hardware aisle about 8:00 at night and a kid maybe 16 came by and asked if I knew where the toilet seals were. His dad, obviously busy with the project, sent him down for the part. They are only a dollar apiece so I told him to buy two in case they had to be doubled up and save another trip.

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The seal is easy. If the bearing preload is set by a crush sleeve, and I believe it may be on this car, you should replace it to be sure you get the preload set right. That’s tough to do on your back under the car…


Point was the seal has been discontinued and how to jimmy a part to fit. Seal was easy, getting the part was not.

Yeah… Mr. @TwinTurbo makes an excellent point yet again and as usual (…yawn, it’d be more interesting to see him post something incorrect sometimes just so I could wave my hand and go Oooh oooh…like in elementary school, but alas, the man knows his stuff and is nearly infallable with good advice).

Sometimes I have to remember that i need to tell people about the things that I just take for granted that they already know, especially when it comes to machines etc. Brings up some funny stories in the past that had a “why didn’t you tell me that in the first place sort of theme”… I’m a work in progress I suppose.

Assuming this car has the original 10-bolt with 8.5" ring gear, the pinion seal and crush sleeve are still readily available.

How does one check pinion preload with the ring gear in situ? No way to freely spin the pinion.

Good point about the preload @Bugmenot … I’d just replace the seal and put her back together as it sits more than likely be just fine.

Reading your post reminded me that I have a strip of wire with 5 or 6 various crush rings in my tool box. I’m clueless where they came from but feel sure that some time long ago I had a rear end pinion out but needed a new crush sleeve and likely it was on a Saturday and the job was promised to be ready Monday at 7:00a.m. It’s unlikely that I ever came up short on that 2 bit part again.

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Haha @Rod_Knox… yeah Plasti-Gauge… I still encounter pieces of it here and there between my home, garage and other illogical or strange places. Tool box drawers, coffee tables, in corners etc…

To be perfectly honest, I cannot recall one single time I actually threw a piece in the trash can… they get “read” or “measured” via the chart and then somehow mysteriously leave the scene…or so it seems. LOL Apparently they have plans of their own and wind up haunting you somehow…

Yeah, I don’t get the ‘hard to find’ comments. Rock auto lists 5 for the 5.0 engine.

But where is it the minute you need it @texases and @Bugmenot ? For 20+ years there were no parts stores open after noon on Saturday here where I worked on cars. And I wonder if any of the McParts stores stock that piece today? Of it the person on the counter even knows what it is. There is only one old local parts store here now and it still closes at noon on Saturday.