Rear Diff Problem

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Jul 17, 2007
Little Rock, AR
First of all just finished the knuckle rebuild on our 86 this weekend. With all of the info on here and some help from a more mechanically experienced person it really wasn't too bad! But you sure aren't kidding when it's said to be a weekend project.....takes a lot of time.

Ok so now on to the NEXT problem. :crybaby: After a quick search here it appears as though the Pinion seal and bearing is bad in the rear diff. Lots of play and just a little leaking oil.

How bad is it to replace all of this and anything special I need to think about? Cruiser has over 250,000 miles so I'm sure I need to replace bearings at the wheels, etc while I'm back there.
Bet it is nice to get the knuckles rebuilt. That is a fun one. Where are you located? I would pull the 3rd member and take it to a gear shop. To rebuild the 3rd member it helps to have a press and takes time to set the gears up right if you have never done it. It is important the gears are setup right or you will be doing it again soon. Have you pulled the rear driveshaft and check the pinion nut?
Nah haven't pulled anything apart yet. Would a worn pinion nut cause something like this?

Only syptmoms I have right now is a little oil seeping out near the driveshaft, not the diff itself, and a fair amount of wiggle that I can tell is not in the u joint and I know it can't be good!

Didn't know how long I could ignore this??

I'm in Little Rock if anyone knows a reputable shop to deal with this in the area?
doh just saw the last post. Once I get done redoing the front brakes I'll pull the driveshaft and take a look!

Maybe one of these days I'll actually get to drive this thing :D
Maybe one of these days I'll actually get to drive this thing :D

I feel quite the same way sometimes. I just got done with a u-bolt flip kit only to pull it out of the garage and find that the engine mounts are now so F'd up that the fan blade is hitting the shroud under light acceleration :bang:. Ordered the mounts today from Cdan. Hope to get them soon. I want to drive may baby again. ;p
I have two 3.73 geared(stock) third members that i pulled from my 60.

only 229,000 miles on them!:D

Littel rock is a ways to ship, though.
You might get lucky and it being just the nut loose BUT I REALLY think you should follow norcal 60 advice on this one. Play = bad bearings which in turn the ring and pinion need looked for wear because of the pinion play:beer: good luck.

edit....just buy a 100 dollar 3rd off a mudder and call it a day
It is also possible to over tighten the pinion on the later 60's (ask me how I know). The earlier ones used higher torque values, later models (like your 86) can overload bearings by overtightening. Also a speedi sleeve may be necessary to stop the leak. Often a small groove is cut in the pinion by dirt @ the seal (not changing gear oil frequently enough), so a new seal may start leaking almost immediately.
Ok so explain this to me like an idiot (when it comes to mechanical, I come close to qualifying anyway).

It seems to make since to go ahead and have the third rebuilt since I don't want to have to deal with this again anytime soon? That way I can replace the bearings and seals in the rear the and be done with it?

I realize without tearing into it I won't know but any reason to think that my third is beyond repair?
you can repair it, ...... or i mean to say have it repaired somewhere $$$$$

But it would be cheaper to get a used one from someone on here.

My understanding is that they don't normally wear out too easily.

I swapped third members on my 60 myself and it was nice and easy. You don't have to be any kind of expert to do it, Im certainly not.

Get a new to you third member, swap it in and you will be set.

If you do it, you will need new gaskets for the axle housing.
The looseness can be caused by an inpact that has further collapsed the crush sleeve that serves only as a way to eliminate bearing play and establish proper bearing preload. The pinion depth, critical to proper gear setup, is established with internal shims. You can likely torque that baby down and be done with it, but pull the outer bearing and have a look when you replace the seal, it should come out without too much fuss. I seriously doubt you will need axle bearings as you have indicated. I have 350K on the originals and they are fine. Come to think of it, I have 350K on all my differential bearings as well since I kept them when I changed the gearsets. They were fine so why replace them?
Quick fix = swap front and rear thirds
If you ever think you might want to regear or go bigger on the tires, do it when you rebuild the 3rd member. You will have to pull the front 3rd and also regear it to the same before you put it in 4 wheel drive. Everything in the 3rd member is replaceable so it can be rebuilt. The only way a 3rd would not be able to be rebuilt I know of is if you damages the housing bad.
PM sent ardave.
Just found this thread.

I'm having similar issues so I thought I would ask:

My rear pinion nut had loosened. It seemed to be causing some vibration as well as a very very noticeable clunking sound while braking. Sound right?

I re tightened the pinion nut, but the clunking persists. Does this mean the rear third bearings are toast???

Sorry for the hijack but it seems to be an appropriate addition to the thread.
If the pinion nut is staked, it won't loosen up..

Wear in the bearings will cause the play that you are seeing (or a crush sleeve dying, rare)

Your best bet is to pull the third and have it rebuilt.
~$250 or so at a shop. Or, you could try it yourself. If you have crushsleeves, I would have someone else do it for you. Crush sleeves suck IMHO..

There is another option that is a LOT of work but is the best IMHO if you have a crush sleeve. Set up the pinion with the crush sleeve and new bearings. When it is perfect, pull it apart. Then have a piece of tbe that is the exact length of the crush sleeve machined and replace the crush sleeve with it.

It sounds stupid, but personally, I hate crush sleeves (tho I have on in my 14 bolt in my 40)
Looked like the pinion nut had been re-staked at some point, so I tightened it (it was Very loose) and restaked it. The clunking while braking persists...

Bearings shot then?
Your U bolts tight??

Bushings good?

Look at your entire rear suspension..

Clunking while braking is not a pinion thing..
Your U bolts tight??

Bushings good?

Look at your entire rear suspension..

Clunking while braking is not a pinion thing..

I hadn't thought about suspension being the culprit. I figured either something with the brakes themselves or the loose pinion.

After tightening and restaking the pinion nut, the driveshaft and pinion feel pretty solid. The brakes are new and work great and are assembled properly.

I'll look over the suspension and see if anything other than flat stock springs seems suspect.

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