Pinion shaft play

[mattcamp]

I have a question for those more knowledgeable than I am about differentials. That might mean everybody, I am not sure. Ok here goes: I have an Aussie locker in my rear diff, I have the whole rig up on jack stands, I was turning my rear wheel back and forth and ratcheting the locker and I noticed my pinion shaft moving in and out when the pressure of turning engaged the locker and the driveshaft began to turn. So at the flange I could see the bearing shield move towards the transfer case and when I let the pressure off it moved back towards the diff, looked like a quarter inch maybe, can I just snug the pinion shaft a little or will that change my backlash or do I leave it alone. -Matt

 

[Prairie Swamp]

I think that independent of the type of differential the pinion bearings should be very tight (pre-loaded.) If in fact the pinion moves forward and aft in line with the drive shafts then the bearings are very worn out.

You sure it's not just your pinion nut coming loose? 1/4" is a lot. At this point try to snug it up you really don't have anything to lose.

 

[FJ40Jim]

Agreed. Remove 4 d-shaft bolts, get a big socket & run down the pinion nut & re-stake it. That might be good enough for a long while.

 

[mattcamp]

Well I hope that is what it is, I will have to

I think that independent of the type of differential the pinion bearings should be very tight (pre-loaded.) If in fact the pinion moves forward and aft in line with the drive shafts then the bearings are very worn out.

You sure it's not just your pinion nut coming loose? 1/4" is a lot. At this point try to snug it up you really don't have anything to lose.[/QUOT

I think that independent of the type of differential the pinion bearings should be very tight (pre-loaded.) If in fact the pinion moves forward and aft in line with the drive shafts then the bearings are very worn out.

You sure it's not just your pinion nut coming loose? 1/4" is a lot. At this point try to snug it up you really don't have anything to lose.

I hope it is just that the nut has com come loose

I think that independent of the type of differential the pinion bearings should be very tight (pre-loaded.) If in fact the pinion moves forward and aft in line with the drive shafts then the bearings are very worn out.

You sure it's not just your pinion nut coming loose? 1/4" is a lot. At this point try to snug it up you really don't have anything to lose.

I will check the nut and see if it has come loose, because you are right, I don't have anything to lose. -Matt

 

[mattcamp]

Agreed. Remove 4 d-shaft bolts, get a big socket & run down the pinion nut & re-stake it. That might be good enough for a long while.

Thank you, I hope so!

 

[mattcamp]

Well I hope that is what it is, I will have to


I hope it is just that the nut has com come loose

I will check the nut and see if it has come loose, because you are right, I don't have anything to lose. -Matt

Boy that series of responses seams wierd, I swear I am not drunk! I was getting calls as I was trying to post. But, maybe I should get a drink, I might start making sense!

 

[cruisermatt]

X2 on cranking down on the pinion nut, however I wouldn’t expect it to be a permanent fix, I had the same issue and maybe 10 months to a year later it was worn out again, but way worse.

 

[Cruiserdrew]

The differential needs to be rebuilt. But I agree tightening up the nut will buy you a short bit of time. Typically the nut doesn't loosen up. Instead, the outer pinion bearing wears, bearing preload wears to zero and the whole shaft gets a bit sloppy, which then loosens the nut.

You might consider swapping your front differential to the rear, your existing rear to the front, and it's likely the worn rear will go for YEARS up front.

In most trucks, the front differentials are still basically new in terms of wear, preload and backlash while the rears are done like yours.

You do need to fix this though. 1/4 inch of in and out slop is a lot and you want to be sure the gears and the other bearings are OK.

 

[mattcamp]

If I use a third member out of a fj40 that's 4.11 and put the locker in it then I don't have to worry about different splines, and I have an extra 4.11 ring gear and pinion shaft out of the same 40(I changed a '73 fj40 to 4.88's) I could put it on the carrier in the front diff and keep that locker in it, that should be good with 35" tires right? Shouldn't that feel like running 31's with stock fj60 R&P's? Does that seem like it would be ok to fix this, I would just need two install kits right? or do you have to use new R&P gears?

 

[RredFJ40]

Yes, but flanges may be different:

I run 4.10s and 35s and like the final drive ratio

 

[mattcamp]

The differential needs to be rebuilt. But I agree tightening up the nut will buy you a short bit of time. Typically the nut doesn't loosen up. Instead, the outer pinion bearing wears, bearing preload wears to zero and the whole shaft gets a bit sloppy, which then loosens the nut.

You might consider swapping your front differential to the rear, your existing rear to the front, and it's likely the worn rear will go for YEARS up front.

In most trucks, the front differentials are still basically new in terms of wear, preload and backlash while the rears are done like yours.

You do need to fix this though. 1/4 inch of in and out slop is a lot and you want to be sure the gears and the other bearings are OK.

Yes, but flanges may be different:

I run 4.10s and 35s and like the final drive ratio

View attachment 1731327

Ok cool, l appreciate the info, I really think I am leaning towards this route, the complete third that I have was out of a front end and if I put the rear locker in it and put it in the front, then I can switch the the front end r&p and throw it in the rear and yeah, I should be in business, if any of that makes sense...... All in due time, I am just glad I have parts laying around in situations like this -Matt