OUCH! My rear end hurts

[truckster]

About a week ago I noticed gear oil under my rear differential (72 Blazer 4X4). No big deal, so I parked it. I drove it down to the office and back (about 4 miles total) and parked it again, and today I noticed a lot more gear oil. I pulled off the back cover to replace the gasket, and there was a piece of metal that went partway through the cover. It's about 1/4 by 1/2 inch and less than 1/16 thick. There were more in the bottom of the housing. Any ideas what gives? All of the metal is flat, so I don't think it's a piece of the ring gear or pinion. Maybe a shim? Do I put it back together and drive it?

Also, it's supposed to be a posi, but I don't see any springs or plates. Maybe it's been replaced before - there was some silicone gasket on the inside of the cover, like maybe they plugged a hole before.

I just got the top off and I really want to drive my Blazer, but I don't want to ruin it. Any help is appreciated.

[70rs/ss]

If there are metal chunks, that ain't gonna just go away. You need to figure out where the pieces came from and fix it, if you can't do it a rear end shop can. If it is a shim (not sure how one would fly out) but that will mean too much clearance and a fatal break could happen, so i would get it fixed. On a lighter note, sometimes a complete used rear can be had cheaper than a repair or rebuild?

[truckster]

Looks like I'll need to keep my eyes on the local pick-n-pulls and see if I can find a replacement.

Maybe I'll just close it up in the meantime and drive it, since I don't think this rear is a posi anyway.

[northerngmc]

It isn't a c clip or part of a c clip is it?

They can fall out if worn. I had it happen on my 59 GMC. Is so the axle will come right out of the housing.



Pinion shaft on right, C clip in center and axle showing spline and C clip groove



Could one have come out and then went through the gears and been cut into pieces?

[truckster]

Originally Posted by northerngmc

It isn't a c clip or part of a c clip is it?

They can fall out if worn. I had it happen on my 59 GMC. Is so the axle will come right out of the housing.

Could one have come out and then went through the gears and been cut into pieces?

Hmm... it sure looks like it might be. I'll crawl under it tomorrow and check. Thanks. If that's it, I might not be in as bad of shape as I thought.

[truckdude239]

a picture would help alot with us telling us whats wrong

[IvelDesigns]

just don't drive it until you figure out what the issue is. i'd hate to see the axle come out of the housing and send you spinning into a ditch.

[truckster]

Here are pics. The metal pieces are flat and are .055 thick. The yellow lines point to some of the holes in the cover. The yellow circle has some of the pieces in it.

I'm also curious to know what kind of differential this is.

Thanks for your help.

[Yukon Jack]

Definitely figure out what is going on before driving it anymore. You could end up in a ditch if something failed or worse, you could kill someone if it failed and you lost control.

[truckdude239]

that looks like a posi unit

[jayharrell]

posi for sure


Did you know it was a posi??

[LONGHAIR]

That's not just any posi....That is a "Gov-Lock". They are well known for scattering parts, though it is usually the little gear parts. That looks like some of the seperator plate parts from the clutches.
Be aware that it is now totally junk. You may be able to get parts for it, but dont watse your time/money.
If that red sealer smear was already there, someone else has already grenaded it and knows it. The simplest and most cost effective way to fix this is to find a good "complete" rear end. Salvage, Craigslist, etc.
If you go that route, be sure to open it up and look inside before you buy. Avoid another "Gov-Lock", look for an open or "regular" posi unit. The parts with the arrows will indicate the "Gov-Lock" indicators, a "regular" Posi doesn't have them. The top two are the governor wheels. The bottom arrow points to where you will see some small gear teeth, behind the side gear.
These are "Gov-lock" parts, a regular posi will just have flat plates with coils springs between them wedged in the side gears.

[truckster]

Originally Posted by jayharrell

posi for sure


Did you know it was a posi??

I thought it was.

I have a new post about it. It's in bad shape.

[jayharrell]

gov posi.. never heard of them. the pic did seem weird though. This is all that i've ever seen of a reg posi.

Only reason i ask is i've seen 2 or 3 guys stumble across a posi on here. I'm going to crack mine tonight to check the ratio #s on the gear and maybe get lucky. LOL...

Any advantage to having a gov posi in a 4wd?? Does it stay locked untill a higher RPM or does it stay unlocked unitll a higher RPM??

[LONGHAIR]

jayharrell,
I never does "lock" that's an optimistic marketing type name. It is a clutch-type unit that has "variable" pressure applied to them. It is supposed to act like an "open" differential until one wheel spins a certain amout faster than the other. Then the pressure is applied to the clutches. The little teeth on the gear (bottom arrow) spin the shaft (upper arrow) which makes all of that happen.
I have heard that they are not too bad in the big 14bolt Full-Floater axles, but in the 10 and 12 they just won't last with any performance up-grades. More power and/or bigger tires can kill them pretty quickly.