I'm refreshing the rear suspension on my car and "While I'm at it..." I figured I'd replace the seals on the diff since I suspect they may be leaking. Anyway, I was just about to close the thing back up... seriously, doing the final check of the gasket surface, and saw this :



Closer on the bottom of the Driver side bearing cap:



Here you can see that it appears to go all the way through:



So, What do I do now?? Is it possible to get a new bearing cap? JB weld ?? I'm thinking worst case, new housing, worst worst case with upside, new complete diff with 3.55s.

Who knows how long it's been broken, I was autocrossing last summer. Could I drive it as is?

Hmm, I just thought that it may have happened when I was taking out the yokes to replace the seals - had to drive them out since they were slightly mu shroomed.

Help!! This was supposed to be a fairly low buck refresh!! The wife ain't gonna be happy if this balloons!

Thanks in advance for any advice!

Dan

 

Contact GTR1999 or Tracdogg2

 

I the cap being broken shows that there is going to be some other problems luckey you found it before if came loose all the way.

 

It's definitely balooning.

 

good eye bro

 

Uh, you would be correct. I've never seen that before. I can't imagine how you'd pop the cap like that and not have it fail totally. Interesting.

 

No to JB Weld and no to driving with it like that.

 

replace the whole thing

 

Unfortunately the only thing to do in this case is to replace the entire housing, and if you are going to replace the entire housing, then you mine as well upgrade to the earlier iron diffs. They are a lot stronger and can be modified to take more punishment. They bolt up directly to the batwings and require a few mods to fit. I'm sure Gary or Mike will chime in soon

 

JB weld...nope, thats way too strong. Really though, it COULD be bad but theres a good chance that you could get away with replacing the cap. Going to steel would be the best bet. I've seen GTR (Gary) do a great job on putting stronger caps and SHCS in one of his threads before "the changes here" . You may in fact get away with just replacing the cap with an original style cap. If you still plan on beating it an upgrade is a good idea.

 

That is a common problem with those 80-82 diffs. One reason I won't touch them, there's nothing that can be done to make then stronger other then install an iron unit, one that is not an stock or exchange one. Aluminum bearing caps, case bearing setup, gear set all part of the problem.

 

There aren't any new caps available so you are looking at getting another case. Like Gary said there is nothing that can be done to make these units stronger.
Mike

 

Can't help much with the rear but compliments on the pictures. Great depth of field.

 

Really, thanks. I'm delving into an area I don't know anything about...

I took the cap off tonight, and did some sleuthing:

Here you can (maybe) see that the break has oil on the surfaces. I didn't hose anything in there since I took the yoke out - which is when it would have broken IF I did it.



I suppose some residual could have run in there in the 2 days since I took them out, but....

These say otherwise: You can see that there is a "polished area on the small part that ends exactly at the break. This tells me that it's been broken for a while.







Anyway, Hmm... Maybe I should put it back in.

Hard to say how long it's been broken. It's not like the motor's a screamer. I did autocross it last summer, but I suspect that the car was built as a racecar at some point in its life.

Who knows?

I'm mildly intrigued by the prospect of putting in an iron diff, but am not real excited about the cost of this... It would cost for the Diff, strut rods & brackets, yokes, and maybe halfshafts??

Sounds spendy.

If I wanted to go junkyarding, could I find any old 70's dana 44 and make it work, or is there something corvette specific?

Another option is to snag a cap from another diff & fit it to what I've got. A forum member offered me a couple of caps from a junked iron corvette housing. Are the bearing races the same OD for an 81 & an iron housing? Seems like I could fit it pretty close similar to how Stinger12 fit his caps to his races, as long as the bolt holes line up. Just go slow & make sure things are concentric.

Just looking for some low buck, get-me-on-the-road-for-a-summer solution until I can move into the next fiscal cycle with a new "vette budget" allocation. Looks like differential fixing moved ahead of Front suspension rebuild on the to do list.

Dan

 

Nice Catch!

good luck finding a used one

 

Dan,
I have the "EXACT" same failure on my 81 rearend bearing cap, driverside in exactly the same spot. I searched and searched for a replacement cap, but could not find one (I finally ended up buying a complete rebuilt aluminum unit to get me by for a while). I'm afraid to say that even if you did find a replacement cap you will have the same problem down the road (I have always been easy on mine and it was still broke). I talked to several knowledgable rearend guys about this and our only option to put this design flaw to bed is to replace our Aluminum unit with one of the earlier stronger units, that is what I'm planning on doing in the future. Best of luck

YBnormal...drive a vette

 

The parts doesn't look that complicated. Could a good machine shop make a new one? Or is there some specific hardening done to the existing part?

 

I was thinking the same thing. Couldn't you have a new pair of caps made up in steel.

 

yes but you have to find what did it to begain with. replacing it should take care of your headack.

 

Yes, that could get you by for a while, but I wouldn't recommend it. The stock bearing caps are designed so that there is minimal rock on the cap after it is seated. By rock I mean the space underneath the cap feet. Having too much rock before you torque it down will result in a slightly distorted bearing race. The bearings will wear abnormally fast, and then you'll be pulling the unit apart again. It is very hard to do this when everything is inside the diff.

On another note, if you get the cap made out of steel, then all your doing is transferring that pressure to another part. Take upgrading your motor for instance. The first thing that will go is the weak diff you have behind it. Okay, so you decide to upgrade the diff to make it really strong. Next thing you know your zerked u-joints shatter in half when the tires great traction. Great, so you upgrade to solid spicers. Next thing you know, you snap a spindle from all that torque. Most likely the steel cap will hold up, but something else is going to go in the diff - they aren't that strong.