Rear Diff leak around pinion support

[Chiclassics]

Hey guys this is kind of a continuation from my last post about axle seal leak. Now that axle seal is taken care (it looks good after couple of days), I am moving on to tackling the next one - pinion support leak.

Some background on this differential: probably was serviced at some point in the last 20 years(was told) . But not necessarily recent, by the looks of the blue RTV around housing. Again, it doesnt tell me anything about 3rd member whether it was all stock or rebuilt at some point - my best guess would be it is all stock. The gears feel good with no vibration/noise/ slack when driving so I want to continue to drive until I feel it needs a service or new gears. I made sure the diff oil is at level. My rear drive shafts are new from WHs.

I have eyed this leak coming from specifically around one of the bolts that holds the pinion support plate. I originally thought it could be from the shim in between but what I noticed is the leak was/is stemming from bottom of bolt over to the ridge of the support. I did take that bolt out couple of months ago put some light layer of thread sealant and put it back in. But the leak hasnt' improved, now that I checked it again. It is like a drop of an oil overnight. Especially after a drive I see 3-4 drops and then it does 1-2 drops overnight.

Attaching some pics. Is there a temp fix until I have this rebuilt? Is this a bad O-ring? or should I take the bolt out again put more RTV around it ? What logically doesn't make sense to me if the O ring is bad and leak is from shim why is leak is happening from the side of bolt which also is located like 1 inch away from bottom of housing.

 

[Yeller]

Pinion seal is leaking and it is migrating with gravity. Doesn’t mean the pinion support isn’t leaking too but you have to start at the highest point

 

[Chiclassics]

Thanks, I noticed that as well. That pinion seal is actually new, under 6months ol. I don't know why there is a leak there - again! , I am planning to address that separately.

To isolate the issue I wiped it off last night as you can see in my first pic the area above the pinion support is fairly dry. So my question is more around is the leak from pinion support can it be fixed temporarily or would it need the third member to come out.

 

[jamesroney]

1. the o-ring is bad.
2. The shims don't prevent leaks. They are 100% dry. all the time, unless #1 happens.
3. The threaded holes are blind, and not wet. There is no reason to put sealant on the bolts, threads, or anywhere else. They only get wet if #1.
4. Your case is beat up and not perfectly flat. Won't leak unless #1. But it bugs me.

There is no reason whatsoever to pull the pumpkin. The 5 bolts holding the pinon support will allow you to remove the pinion, and support as a unit. The only way that you get oil leaking past the bolt is either the o-ring is bad, or you have a crack in the housing where the bolt threads are. Very rare, almost never happens, unless you play in the rocks and someone put a pinion guard on it.

You can prove this to yourself. The bolt is not a plug. You can take out that leaky bolt, and leave it on the workbench. It will not leak more. (unless #1 above) Obviously don't take out more than one. And don't drive around for long without the bolt in there. But it will prove the point.

And I'm with @Yeller When you have a leak up high, it looks like a leak down low. You really do need to clean things and fix the leaks as you find them. It's a $15.00 seal. You KNOW it's leaking. Service it first. It is not money wasted.

 

[Yeller]

Is there oil on the dust shield? If not the leak is around the outside of the seal. Which is probably the case seeing you put a new yoke on as well. When installing a new seal use locktite or hylomar blue on the outside of the seal. If your concerned about the pinion support leaking as well, I’d fix it at the same time, lets you do the pinion seal on the bench since you have to pull the pinion support to change the oring on it.

 

[Chiclassics]

All right - O ring it is then. Ill see when I can pull this out or find a replacement 3rd member.

 

[BOBS 2 68S]

Is the axle vent "venting"?

 

[mock]

If you’re going to do the pinion seal, make sure you know if you’re differential was set up with shims or a crush sleeve

 

[Grey owl]

If you’re going to do the pinion seal, make sure you know if you’re differential was set up with shims or a crush sleeve

Hmm, all 9 inch fords use shims to set pinion depth. That has nothing to do with the crush sleeve !! The crush sleeve is used to preload the bearings.

 

[Dylan_Shaffer]

Hmm, all 9 inch fords use shims to set pinion depth. That has nothing to do with the crush sleeve !! The crush sleeve is used to preload the bearings.

You can set pinion preload using either shims or crush sleeve so it is relevant here if pulling the pinion nut to ensure it’s reassembled with proper bearing preload.

 

[Grey owl]

You can set pinion preload using either shims or crush sleeve so it is relevant here if pulling the pinion nut to ensure it’s reassembled with proper bearing preload.

What diff are you referring to, i have never heard of a 9 inch ford using shims to set pinion bearing preload. The Dana 30 or 40 yes they use shims.

 

[jamesroney]

What diff are you referring to, i have never heard of a 9 inch ford using shims to set pinion bearing preload. The Dana 30 or 40 yes they use shims.

The aftermarket sells replacement for the crush collar that consists of a solid spacer, and select fit shims.

I've written on this topic far too many times. So no more.

 

[Grey owl]

The aftermarket sells replacement for the crush collar that consists of a solid spacer, and select fit shims.

I've written on this topic far too many times. So no more.

I checked it out. Not sure i would use it on a carrier style diff. But its an option.

 

[jamesroney]

Motive sell one, Ratech has one, Yukon has one, Richmond has one. Summit carries like 5 different ones. They are all about the same. $20-$30.

The ACTUAL required thickness of the "crush sleeve eliminator" or "pinion bearing spacer" is defined by the machining tolerance in the pinion support housing itself. The better Nascar teams determine the required thickness, and then machine a solid spacer that exact thickness...and marry it to the pinion support.

When the Cup cars went to the Next Gen car the teams started dumping excess inventory of 9 inch drop outs. Most were the Motorsport Nodular housings, with 31 spline full case detriots and Daytona pinions with the coolant pump drive belt. For a while you could get them for a couple hundred bucks. The nicer ones had the actual thickness of the precision machined solid spacer engraved right on it.

It's a little bit funny, because the RIGHT way would be to settle on a nominal thickness, and blueprint the cast iron support to match the spacer. Then use the same spacer across the teams. If you do it right, you would never have to use a pinion depth shim at all. (the big one with 5 bolt holes in it)

There's no real reason why differentials need shims. They are just there to make up for machining variation in mass production. Funny thing is, I've built more than a few Dana 44's where the pinion depth shims were dead nuts from one housing to another, and they are all pretty similar. But I built TeraFlex 60 that was a completely different nominal number.

Crush sleeves are now used bv every major axle manufacturer on the planet. Starting being adopted in the 1960's and literally hundreds of millions of installations. And they work.

 

[Grey owl]

Never heard of it,

Motive sell one, Ratech has one, Yukon has one, Richmond has one. Summit carries like 5 different ones. They are all about the same. $20-$30.

The ACTUAL required thickness of the "crush sleeve eliminator" or "pinion bearing spacer" is defined by the machining tolerance in the pinion support housing itself. The better Nascar teams determine the required thickness, and then machine a solid spacer that exact thickness...and marry it to the pinion support.

When the Cup cars went to the Next Gen car the teams started dumping excess inventory of 9 inch drop outs. Most were the Motorsport Nodular housings, with 31 spline full case detriots and Daytona pinions with the coolant pump drive belt. For a while you could get them for a couple hundred bucks. The nicer ones had the actual thickness of the precision machined solid spacer engraved right on it.

It's a little bit funny, because the RIGHT way would be to settle on a nominal thickness, and blueprint the cast iron support to match the spacer. Then use the same spacer across the teams. If you do it right, you would never have to use a pinion depth shim at all. (the big one with 5 bolt holes in it)

There's no real reason why differentials need shims. They are just there to make up for machining variation in mass production. Funny thing is, I've built more than a few Dana 44's where the pinion depth shims were dead nuts from one housing to another, and they are all pretty similar. But I built TeraFlex 60 that was a completely different nominal number.

Crush sleeves are now used bv every major axle manufacturer on the planet. Starting being adopted in the 1960's and literally hundreds of millions of installations. And they work.

Thanks. Great info, i am old school I will stick with the simple crush sleeve.

 

[Broncobowsher]

That pinion seal looks mauled. The metal part of it has a bunch of uneven marks like it was beat on with a hammer and no driver was used to give it an even install. Good chance the leak is between the seal and the pinion support and not the seal to the yoke.

 

[ntsqd]

I've kilt dead two crush sleeves in what I consider to be normal use. I've posted about it before, they crushed further. How, I don't know and honestly don't really care. No more for me, spacers only.
I was paid to set up 7 of less than 250 ever made differentials. We made solid spacers that were long and kept cutting them down on the surface grinder until we got the pinion bearing preload required. Did the same thing for the front wheel bearings on a friend's off-road race truck. Stock, required use, spindles were puny little things. Made solid spacers and kept thinning them down slowly until we had the desired bearing pre-load. Nice thing about a spacer is that the bearings are made to such incredibly tight tolerances that you can replace them without going thru setting up the pre-load again. And in the case of the off-road truck we could run the spindle nut torque up high enough that we gained a LOT of strength in the assembly.