Stephen Irons

Hello All

I apologised up front for bringing up a subject that I’m sure has been dealt with many times before!

But, it has become apparent that the differential on my 1978 is beginning to show signs of wear in the yoke inner ends. (well, actually only one side at the moment) I detected a slight change in camber angle and inspection reveals that the yoke is indeed moving “inwards” towards the centre of the diff!

The harsh reality is that at the moment I simply cannot afford a “Rolls Royce quality” rebuild of the diff, and so I am wondering if a replacement of just the aging yoke(s) is feasible? Or, indeed if it is possible for a “home mechanic” of reasonable ability to make such a change.

Any thoughts or advice greatly appreciated!

BTAL

Very doable. Replaced my yokes, outer seals and c-clips 18 months ago. Just drop the diff, open it up and replace.

Your shipping costs will probably be more painful than the job itself.

Cheers

thegazman

Sounds like the retained clip is off of the end of your yoke inside the differential. You can make this repair yourself with a little work. You have to remove the differential cover to gain access to the yoke retainer clips. If the clip came off I would replace both yokes with new ones and at the minimum install new yoke seals while I was in there. If the yoke moves in and out it will make the rear your vette squirrely on curves.

Gale Banks 80'

Well there is even a more Back Yard way to do it. Remove the Yokes and Weld up the Ends were they are worn providing the Grove for the Clip is still there. Once Welded grind it down so you get the right clearance. The Weld will be hard so it won't where out to fast. I have never done this before but I have herd of it being done. The other option is to just buy another used diff with less wear. A Guy in Centraila Washington sells them for $300 that might be an option to. Then sell Yours. Neither of these options are the one for a performance Car but they are options.

Stephen Irons

Thanks for the tips guys!

I'll no doubt need a bit of a "how to" later. BTAL, I'd be interssted in a litle detail on the process when you get a moment. In the past I've out on a new composite spruing, and done the UJs and the bearings have been replaced etc, so I'm hoping much if it will come away OK, but would like info on the actul "diff drop".... for example, do I remove the crossmember or take the diff off that....? Do the seals just "pry" out?

Next step is to investigate the supply options for yokes, and seals etc.

drwet

Remove the diff by dropping the crossmember. Its pretty obvious how to do that. Just unbolt everything until its free to come out. You will probably have to pry on the crossmember to get it to release from the frame. They usually stick. Back the bolts out a couple of turns when you pry it loose so it doesn't drop too far. Open up the diff and remove the cross-shaft. There is a pin at one end that retains it. Unscrew the pin and remove it. This allows you to remove the cross shaft. Once the cross shaft is out, push the output yokes toward the middle of the diff and remove the C-clips that retain the yokes. Once the clips are removed, the yokes just pull out. While they are out, replace the seals. They just pry out and you carefully tap in a couple of new ones. Install a couple of new output yokes and you're good to go. Its a little hard to describe the whole process in words, but if you could see it done, you'd realize the whole procedure is very simple. The biggest part of the job is getting the differential out of the car.

Gale Banks 80'

Once out do not be tempted to remove the Big Nut of the Input Shaft to get to the Seal. Its set at a preloaded position and there for must go back in the exact spot it came from. So You ll need to mark a Witness Mark so You can put it back in the same spot.

Stephen Irons

Thanks Guys!

Is there really such a thing as a simple process on a Corvette?

The search is on now for reasonably priced Yokes and seals!

Lynn Colvin

I apologize if I'm jumping into this discussion in the wrong location. It's my first time on.

Can the rear end axle yokes be changed with the differential in the car? Also is there a bearing that needs changed while doing it?

Thanks
Lynn

sly vette

Be careful of the yolks you buy. Many are not hardened. I Know of a great builder that sends his out for heat treat for this reason.

Crash80

As I recall, once you get everything to the point of getting the differential cover off, you are really close to having the entire unit out anyway. I suppose you could do it in the car but the cover is part of all the suspension bits that you remove anyway.

joewill

yes but extremely difficult, you have to get the rear cover off and out of the way.. dropping the rear end is just a small incremental after all the other stuff you have to do to get to it.. strut rods, exhaust, half shafts, spare tire, rear crossmember,

one should always replace bearings and seals if you can get to them.. but if you have to save money, then no, you don't have to change them..

as a general rule, and murphy's law, a seal you do not replace, will immediately start leaking after you get it all back buttoned up.


here are examples..


http://www.ebay.com/itm/1980-81-82-C...item519c1800d6


http://www.ebay.com/itm/1963-79-Corv...item588cd36a43

my 76 ray

The differential is held to the crossmember by bolts that go through the crossmember into the differential cover from the top. These are very hard to get to with the body on top of it. It is much easier to remove the two bolts that hold the crossmember to the frame and get the differential out where you can work on it. The bolts that hold the cover to the crossmember are in the holes in the crossmember.

Crash80

My apologies, I assumed the 78 had the same batwing design like my 80 did.

Lynn Colvin

It's actually a 75 model. My 75yr old dad bought it and I'm trying to help him repair a few small issues with the car. Everything seems to be ok but the right yoke has a squeak under a load. Thanks for your help!

Lynn

Crash80

Have you ruled out that u-joint is not the culprit?

Mike Ward

Not likely to be the yoke itself.

Lynn Colvin

It has a new U-joint and while on a jack with the wheel under power it is quite and smooth running. It's when the yoke is pushed inwards is when the squeaking happens.

Thanks for your input.

Lynn Colvin

I will try changing the u-joint. It had been changed when he bought the car but, that does not mean it's not the culprit.

I'll let you know how it turns out.

Belgian1979vette

Worst part is dropping the diff.