pinion seal leak/crush sleeve/preload

[Overlord]

Will the front pinion seal leak even with the hubs unlocked and not in 4WD?

When replacing the seal, is it necessary to replace the crush sleeve according to the FSM? I've read that if you don't replace the crush sleeve, you can mess up the bearing preload.

 

[landtoy80]

If the 80 diff is the same as the 60, then you can. I bet they are about the same.

The direction in the Hanes manual shows how to do it without removing the sleve.

I have done it a couple times after rebuilding the diff. The seal still leaked.
You want to put RV sealant on the lip of the seal where it goes into the diff. The metal part of the seal, not the ruber part.

You need a good dial (not post or clicker type) in/lb torque meter so you can check the preload on the backlash.
Do a search on pinion seal under landtoy80 and you will see what I mean about the preload of the backlash.
When you turn the flange with the hubs locked, you can feel the backlash. It turn back and forth. That is what you measure BEFORE you take it apart.
Then you add a couple in/lbs (per the service manual) and tighten the pinion nut untill you get the required preload on the backlash.

Again I assume that the 80 diff is the same as the 60 diff.

 

[soggy60]

Yes, the oil seal on the pinion can be R&R'd without replacing the crush sleve.

After removing the drive shaft, 'un-swage' the big nut ( you should replace that nut).
Tease off the companion flange.

Tease out the old seal.


Press in new seal, re-set flange, tighten big nut, swage big nut, replace drive shaft: done- about 1.5 hours.

 

[Mark W]

The seal can be replaced without affecting the crush sleeve or the bearings.

Backlash and preload are two different things. Backlash can only be measured linearly (with a dial indicator). It is a measurement of movement. It is measured at the outer edge of the ring gear. Preload is measured with an in/lb torque wrnech. It is a measurement of force. It is measured at the end of the pinion.
What you want to measure is the force it takes to turn the pinion *before it takes up the backlash and the resistence of the ring gear comes into play. That's not a lot of movement. Ideally you will not be measuring the amount if force needed to start the pinion moving, but the amount needed to keep it moving (it will be less by a small amount, but since the total measurement is a small amount, it matters,

If you retorque your pinion nut to the levels that you will be able to achieve with a torque wrench while laying under the rig you will not affect the crush sleeve. It takes a lot more force than that to crush it (181-325 ft/lbs by the factory FSM).

Just make sure that the preload is within factory spec (or reasonably close to it at least) when you put it backtogether. That may be difficult to achieve because (see the rest below...)


However, leaking pinion seals are almost always a sign of loose pinions. And loose pinions are always due to pinion bearing wear. The outer pinion bearing wears faster than the inner on the rear diff. The front diff is *generally* the opposite, with the inner wearing faster (not always because the inner bearing is larger than the outer). Worn (out) bearings will not approach factory preload without further compaction of the crush sleeve. If the wear is primarily of the outer bearing, you *can* compact the crush sleeve more to snug the bearings back up without having much effect on the backlash. BUT, a worn bearing is no longer as smooth as it was and the rougher surfaces will wear faster once they are pressed firmly back into contact. Sometines leadingto catostrophicfailure if a heavily worn bearing is simply tightened down.
If the inner pinion bearing is significantly worn you will increase the backlash beyond factory parameters when you crush the sleeve more.

Mark...

 

[landtoy80]

Can't you, if you use reuse the pinion nut, just tighten the nut to the same place on the pinion?
The two times I replaced the seal on the 80, the nut ended up at the same place each time I tighten it.

You need to take care not to mess up the threads on the pinion from the crushed part of the pinion nut. I messed up the threads on mine but I had the right size tap/die from a past incounter with a leaking pinion seal on a Toyota pu.

 

[Overlord]

The seal can be replaced without affecting the crush sleeve or the bearings.

Backlash and preload are two different things. Backlash can only be measured linearly (with a dial indicator). It is a measurement of movement. It is measured at the outer edge of the ring gear. Preload is measured with an in/lb torque wrnech. It is a measurement of force. It is measured at the end of the pinion.
What you want to measure is the force it takes to turn the pinion *before it takes up the backlash and the resistence of the ring gear comes into play. That's not a lot of movement. Ideally you will not be measuring the amount if force needed to start the pinion moving, but the amount needed to keep it moving (it will be less by a small amount, but since the total measurement is a small amount, it matters,

If you retorque your pinion nut to the levels that you will be able to achieve with a torque wrench while laying under the rig you will not affect the crush sleeve. It takes a lot more force than that to crush it (181-325 ft/lbs by the factory FSM).

Just make sure that the preload is within factory spec (or reasonably close to it at least) when you put it backtogether. That may be difficult to achieve because (see the rest below...)


However, leaking pinion seals are almost always a sign of loose pinions. And loose pinions are always due to pinion bearing wear. The outer pinion bearing wears faster than the inner on the rear diff. The front diff is *generally* the opposite, with the inner wearing faster (not always because the inner bearing is larger than the outer). Worn (out) bearings will not approach factory preload without further compaction of the crush sleeve. If the wear is primarily of the outer bearing, you *can* compact the crush sleeve more to snug the bearings back up without having much effect on the backlash. BUT, a worn bearing is no longer as smooth as it was and the rougher surfaces will wear faster once they are pressed firmly back into contact. Sometines leadingto catostrophicfailure if a heavily worn bearing is simply tightened down.
If the inner pinion bearing is significantly worn you will increase the backlash beyond factory parameters when you crush the sleeve more.

Mark...

I found a little slop in the pinion. So, it looks like the bearing(s) are worn. Is this something that should be taken care of right away? Or can I just replace the seal for now and down the road replace the bearing(s)? Also, when replacing the pinion bearings, is it a good idea to also replace the side bearings while one has the diff apart?

 

[Mark W]

If you have a loose pinion that is causing leakage, you have to eliminate the slop or it will just leak again quickly. Depending on just how much wear you are talking about and if it is primarily in the outer or inner bearing(or both?) you may be abnle to snug it up after installing the new seal and get some more life out of things. But you will need to keep a close eye on the diff to detect the return of the slop due to accelerated wear. You might get another 50K out of it, or you might need to go in and replace the bearing(s) in another thousand miles or so. No way to know without laying hands/eyes on it, and even then it is a best guess kind of thing in most cases.

The side bearing are usually good until just a couple of days short of eternity. They see little load are well lubed, and last forever. Unless you run the diff dry of course...


Mark...

 

[landtoy80]

Mark,
WHat is the free play called when you turn the pinion back and forth if its not called backlash?

 

[Mark W]

Mark,
WHat is the free play called when you turn the pinion back and forth if its not called backlash?

????? Backlash of course??? No disagreement about that.

The total slack in the diff (cumulative of the pinion and ring gear and the side and spider gears or the locker if so equipped) would be called backlash too.
Just making sure that Sean understood what he neaded to be concerned with and what /how he needed to measure.


Mark...

 

[landtoy80]

Yes, it does get hard to under stand when trying to talk someone through working on a diff.
I try to be clear as I can but sometimes its clear as mud