Help on Differential Gasket please,
69 F-100 360- 2 wheel drive

I am replacing axle seals and bearings. Was suggested to change the gasket and seal at differential. Mine is leaking a little.

Heard from an outside source that replacing the gasket was very diccicult because the insides kind of collapse on you when you pull the " yoke". I don't know what it should look like to put it back together.

Is this a difficult job?

It was suggested that I just loosen the bolts, squirt in Form-a-gasket and then tighten up?

Any suggestions ??
Posted in 69-72 and differentials.

Thanks,
Richard

 

If the 3rd member gasket is not leaking, I would not replace it. Same with the seal. It has been awhile and I don't have the procedure in front of me but the insides will not fall apart.

 

Ive pulled many 3rd members from 1/2 ton to Semis and have never had one fall apart ( yet) maybe i'm just lucky. Found alot of broken pieces but they were still pretty much intact when i pulled them. John

 

If the 3rd member gasket isn't leaking, I wouldn't mess with it, If it's never been out, you'll have h*ll contending with those copper washers, they're tough to dig out. I'm 100% blue oval, but I've never seen many that didn't have a leaky pinion seal, those aren't that difficult to replace. Good Luck !

 

If you remove the yoke then you should know what you are doing. The bearing preload is held by a crush collar that takes 400-500 ft.lbs. of torque to initially set properly. One it has been crushed it doesn't take much to overtighten it and put too much preload on the bearings. This is not a nut that you just hammer on with an impact or tighten all the way up with a big ratchet. I have just an aquired feel for tightening these and it is hard to explain in words but I would think maybe around 90-100 ft.lbs. but it would vary depending on the amount of wear in the pinion bearings. I have seen 9 inch rear ends ruined because the pinion hut holding the yoke was overitghtened. This is a good place to apply the old axiom"if it ain't broke don't fix it"

 

Check your axle vent tube and hose located on the left side. If clogged up this will cause a seepage at yoke seal and diff. gasket over time.

 

I will see if I can find an axle vent tube. Got my son to clean the mud off - we then were at least able to fingd the filler plug. Is the vent tube anywhere near that?

Richard

 

Couple of thoughts here:
1. Differential gasket: There are actually 5 sealing locations on the Ford 9" rear. 2 axle seals (not visible w/o removing the axles), 1 chunk or pumpkin gasket face (with the 10 bolts), 1 pinion carrier gasket face (with 5 or 6 bolts, cannot remember exactly), and the pinion or yoke seal.
The differential seal for the chunk or pumpkin was a gasket at first, then was switched to an RTV- type sealant later. You don't need a gasket per se, just a tube of RTV. If you remove the chunk, you can use the opportunity to change the rear axle seals at the same time.
By removing either the pinion carrier or the yoke to change the gasket or replace the seal, you risk changing the depth of the pinion gear - which requires that the process of "setting up" the differential be accomplished. Note that without the proper tools, this is an expensive machine shop process. Unless these are leaking badly, don't mess with them. (You can use RTV on the pinon carrier too.)
You MIGHT get away with changing the pinion carrier gasket and not setting up the differential. Try tightening the bolts first, though, to see if that slows the leak (if there is one) to an acceptable level. Willowbilly is absolutely correct here - if it ain't broke, don't try to fix it.

Vent tube: Is screwed to the axle tube, and holds the rear brake hose to the axle. A short length of rubber hose (not the rubber brake line) is clamped to this tube from the factory, and often falls off or gets ripped off when it ages. Some vent tubes were hollow, some had a little ball inside to act as a one-way valve. I just drilled mine out and made sure the rubber vent hose was clamped to the frame up out of the way. I don't go mudding, so you may want to do something different.

When you remove the vent tube for cleaning, the brass Y for the rear brake lines will hang loose. The good news is you will not open the brake system, so you can just leave them be while you fix the vent tube. Note though, that if your rear brake lines are starting to rust, the movement of the rear rubber brake line while working with the vent tube MAY crack the lines at the weak points, which will require they be replaced or fixed.

 

Thanks to all

I had the half axles out when replacing seals to stop leaks into the brake drums. ( One bearing was gone and the other rumbling, so replaced those as well.)

I may try just the big 10 bolt gasket this weekend which I understand will require pulling the half axles again.

I will definitely check the vent tube and tighten all the bolts.

Thanks again,
Richard