1969 Differential

[Bill Stephens]

I'm restoring the rear suspension of my 69. There is oil everywhere, and I was planning to change the differential gasket. I now think that at least one of the seals is also leaking. I'd like to get this thing back on the road, but I hate to put it all together with the differential still leaking. How hard is it to replace those seals? I think there is one at each drive shaft. Does the differential need to come out? I've got it on jack stands, so it's hard to maneuver.

I'd appreciate advice. I'm about ready to just hook everything back up without fixing the leak. Thanks.

[Chuck R.]

Re: 1969 Differential

The last thing I would want is to put all kinds of time into cleaning up the driveline and under carrige of the car only to have diff. grease thrown all over it again not to mention the fluid loss concern. I would get the seal fixed.

You can do it on the car, but it will be involved.

First, your going to have to take the load off of the spring as the spring is mounted to the rear cover that needs to come off.

This means taking the spring links apart at each side where they attach to the trailing arms. Extreem care must be execised when de-arching the spring as there's a ton of latent energy just waiting to release.

With the tension off the spring, you can remove the four bolts that hold the spring to the cover and remove the spring.

Now you can go to work on pulling the half shaft retainer bolts out and pull the half shafts away from the yokes. You might have to pry them out as the trailing arms may be appying inward pressure. Be sure to wrap the loose grease cups with masking/electrical tape so that they don't pop off.

With that done, you can now go to work on the rear cover bolts.

With all cover bolts loosened up but not removed, carefully pry the lower sealed edge where the cover mates to the diff. away so that you can drain off the grease.

Once drained, finish removing the cover and clean all flanges taking care not to contaminate the gearing.

If you follow the line of the yoke into the diff. you will see an external snap ring that holds the yoke in place. Remove the snap ring and the yoke will slide out. Be very aware of any shims that may be under the snap ring and stuck to the carrier.

Now you can get to the seal and pry it out and install the new seal, making sure that it's gently tapped in nice and square. Others may say otherwise, but I put a thin smear of gasket sealer around the outside metal perimeter like "Indian Head Gasket Cement" just as an added measure. While it's apart, do both sides, the seals are cheap and you don't want to have to re-visit this.

Then it's re-assembly in the reverse order.

Now is the time to take the hard look at the components that you have free for possible replacement as follows.
Diff. cover spring mount ears looking for cracks
Spring mount bolts for deterioration or rounded threads
Replacing the spring link assemblys with new kits (a must)
New liners for the spring leafs including center bolt
New yoke snap rings
U-joints both inner AND outter

If you don't have repair manuals, you should definately get one as this is involved and potentially dangerous especially in dealing with the spring and it's un-loading process.

Let's not forget proper supporting of the car and safety measures prior to tackling this project.

This is just a quick (yeah right ) 1,2,3 explanation Bill, hope it gives you some in-sight.

[Bill Stephens]

Re: 1969 Differential

Chuck,

Thanks Chuck. I've already removed everything from the differential except for the drive shaft. The differential casing is sitting on a floor jack, I've removed the cross member, and the car is on stands. I'm actually putting in heavy duty (7-leaf) springs, changing all the bushings, bolts, etc. It sounds like, given what I've done, it doesn't make any sense not to follow through and change the seals.

From what you said, it's probably easiest if I take off the drive shaft, drop the differential, and do the seals and gasket on the work bench. The manual says that you have to be careful to realign various things, and you said to be careful about shims. That all says to me I should go through the pain of pulling it off rather than doing it on the ground. That way I can also change the front seal.

Thanks again for your help.

[Chuck R.]

Re: 1969 Differential

Yep, if your that far along, I'd throw ahem..place the diff on the bench where you can get up close and personal and do it right.

I had a beautiful geasey stripe across the undersides from driver's to passenger's side wheel wells from a spent pinion seal.

Mix in twenty or so years of dirt and grime and I tell ya Bill, Norman Rockwell couldn't have done better, it's beautiful

Good luck,

Chuck