Frogday

It was nice out this weekend, so I decided to take my C3 for a spin. Probably cruised around for an hour or so and then on my way home took a hard left a little more spirited than usual and heard a loud clunk from the rear end. I had replaced all the U-joints maybe 200-300 miles ago, so I kind of ruled that out. Pulled into the garage and let it cool down for a bit, and when I came out to check there was a small puddle of gear oil. So I get under the car and can see the cracked differential case...not good.


Dropped the differential tonight and here is what I find. Something about that ring gear just doesn't seem right.


Not the best news, but at least I made it home without being stranded. I guess I see a rebuild in my near future.

GTR1999

You'll want to check the posi case for cracks as well. Use a quality RG set from Tom's and I would recommend posi tuning at a minimum. If you need a case don't use a new loaded Eaton.

Frogday

Would this need more than a visual inspection for cracks, like magnaflux or something? If the I end up replacing the whole unit, I'll try to find the correct date coded piece.
Thanks for the tips!

GTR1999

Most times the cracks are effident with brake cleaner and an air line. If you look up my threads on the diff it will show you a lot on what to look for and how to build the best out there.

Frogday

I spent a few hours reading through your posts and found a long detailed doc about rebuilding the differential. I had an idea that it would be more than I can get done without a lot of specialized tools I doubt I'd ever use again. I can see this is something I will have to send out to have rebuilt.

dr1

so why did it grenade on a sharp turn? was there a bolt floating around in the case or something?

Frogday

No idea. I guess the loud noise it made was the gear tooth breaking. Nothing extra came out of the case after I took the differential out of the car. I ran a magnet around inside the gear oil and only shavings of what used to be part of the gear were in it. Wife had to correct me and remind me it was a right turn.

gingerbreadman1977

the fact that you can do that with her in the car is awesome. what a keeper !!

GTR1999

you can stamp the brg caps and then take it apart to take a closer look. I have walked guys through this job at home. If I can help let me know.

7T1vette

There had to be something else in the diffy...or another part in the unit broke off first. Something hard got into the teeth of the ring gear and broke off that tooth. It was such a violent break, that the ring gear is fractured through! (look at the crack on the OD of the ring at the base of the next tooth. You need to check the pinion to see how bad it looks. It must have been involved when the break happened.

bashcraft

I had the same thing happen to an '82 Buick Riviera. The diff started banging when my wife was driving it. Took it out and it looked exactly like Frogdays. There was nothing else in there that would've caused it.

63mako

http://forums.corvetteforum.com/c3-p...-diff-f-s.html

7T1vette

The only possibility would be that just the tip of that tooth broke off...then it got lodged in the gears at that same tooth and broke the rest of it. And I think that is a big stretch in probabilities. The broken tooth, and cracked ring gear indicate that something got lodged in the ring/pinion teeth and cause an instantaneous fracture.

Anyone else have a possible cause for this failure mode?

bashcraft

I can't be sure, but that doesn't look like a fracture to me. It doesn't go clear through. Might be nicks or scratches. Or maybe you're seeing something I'm not.

Frogday

I'll probably take it apart somewhat to get a closer look inside. Definitely going to have to send this out to be rebuilt. In searching around for info about this I saw mention of Bair's. Someone on the C1 board mentioned sending one off to them for rebuild. Any thoughts on Bair's? I hadn't heard of them before.

63mako

Tom's differentials is out by you. They will have the parts you need and do high quality rebuilds.

GTR1999

FYI,Tom is no longer building anything.

mrvette

Yes, I had something similar happend to me in a 3/4 ton Dodge van.....I had the cross shaft out and pulled the axels for seal service, bolted it back up, and 2? years of daily driving later, I start out from a traffic light, get up to maybe 30 mph....and BANG

That silly SOB, locked up tight, and I slid all over the dry road coming to a stop, lucky the lady behind me locked em up or I would have been hit....I remember the total scoule on her face from the panel mirror.....

anyway, there was only ONE thing to cause that kind of damage.....and instant destruct....I backed it up and dropped the broken cross shaft into the bottom of the case, and limped home for some 10 miles at 0 mph.....

dropped it outta there and put in a 9.25 Posi rear, pulled the cover, and WOW what a shrapnel patch.....:yes nod:

vetteman1*

I need to replace the Shear Pin/Roll Pin/Pinion Shaft as well but mine is not .0749 mine is .073 in daimater? Any sugestion. Everyone I find is the 3/4 one. 69 vete Open rear, Not Posi

vettebuyer6369

You are responding to a post made over 10 years ago.