Over tightened Pinion Nut

[stapleg]

Did I mess this up badly?

I think I may have made a pretty significant mistake while replacing the pinion seal on my rear differential (first time ever going near the drivetrain). Before taking things apart, I dimpled everything with a chisel so I could put it back in the same position and hopefully maintain the original preload. The problem is I went too far when tightening the nut with an impact - ended up overdoing it to the point where the pinion wouldn’t rotate at all.

After that, I loosened it slightly until my marks lined back up again. Now I’m noticing a faint whirring noise when I let off the throttle. It’s not super loud and only seems to happen at certain speeds or when going downhill.

My guess is I may have over-crushed the crush sleeve, and now that I backed it off, the preload might be off. Would nudging it a little tighter help, or is that not the right move? Not sure what to do...

Thanks!

 

[eric1514]

I've never done this job, but I did stay at a Holiday Inn Express once. The Factory Service Manual says:

CAUTION: Never loosen pinion nut to decrease pinion
rotating torque and never exceed specified preload
torque. Failure to heed caution may result in
damage.

Also from the FSM

The pinion gear
rotating torque should be:
² Original Bearings: 1 to 2 N·m (10 to 20 in. lbs.).

If it was me, I'd start over with the proper tools and procedures.

Good Luck.

 

[24turbo]

If you tightened the pinion to the point it wouldn’t turn you have likely ruined the bearings (especially using a impact)The rollers probably dented the races and will fail eventually.
Change the bearings and redo the set up with a new crush sleeve.

Backing off the nut may result in the nut coming loose and all kinds of bad stuff happens. It is no longer by being retained by the torque of being tightened to the bearing and crush sleeve. The only thing keeping it in place is the friction of the threads(aka pretty much nothing)

My general rule with bearings is don’t use an impact to tighten them. It rattles the crap out of what you are using it on which doesn’t do the bearings any favours.

 

[WWDiesel]

You probably have damaged one or both pinion bearings along with over crushing the crush sleeve. The noise you hear is due to the change in pinion gear depth/position on the ring gear. The contact pattern on the ring gear teeth has slightly changed especially when you are costing and the teeth's heal and toe contact is most likely not centered and even which is making the noise. Keep running it like this and it could eventually damage the ring and pinion gears to the point of having to replace them to stop the noise.
Bottom line; you will have to let a mechanic with building differentials experience and knowhow replace your pinion bearings and install a new crush sleeve and set up the rear end using the proper tools to the correct specifications.
Using impacts on pinion nuts is a big no no!

You must be registered for see images attach

 

[stapleg]

You probably have damaged one or both pinion bearings along with over crushing the crush sleeve. The noise you hear is due to the change in pinion gear depth/position on the ring gear. The contact pattern on the ring gear teeth has slightly changed especially when you are costing and the teeth's heal and toe contact is most likely not centered and even which is making the noise. Keep running it like this and it could eventually damage the ring and pinion gears to the point of having to replace them to stop the noise.
Bottom line; you will have to let a mechanic with building differentials experience and knowhow replace your pinion bearings and install a new crush sleeve and set up the rear end using the proper tools to the correct specifications.
Using impacts on pinion nuts is a big no no!

You must be registered for see images attach

You don’t suppose this is something I could do pretty straightforwardly in my driveway? Just disassemble, replace crush sleeve, reassemble with proper preload?

Im pretty ignorant to all things related to differentials, but this is obviously forcing me to wisen up lol

 

[Shankster]

You don’t suppose this is something I could do pretty straightforwardly in my driveway? Just disassemble, replace crush sleeve, reassemble with proper preload?

Im pretty ignorant to all things related to differentials, but this is obviously forcing me to wisen up lol

If I were you that's what I would try first - get a new crush sleeve and install it and hope that does the trick. I used a little 1/4" torque wrench for bicycles to get the proper preload.

I've seen pros use an impact wrench on pinion nuts but you have to be super careful and go really slowly. It's safer to use a big torque wrench or cheater bar but with those you need a way to hold the yoke which can be a challenge - search on YouTube for people rebuilding their Chrysler 8.25 and you'll see a few ways to hold the yolk. I forget what I did but I think I might have used a big pipe wrench with the end of the handle against my garage floor to prevent it from turning. And as you've found out, you can't just back the nut off to reduce the preload - any time you go too far you need to start over with a new crush sleeve.

As others have said you might have done some serious damage but then again you might not. I'd try the cheap easy fix first before you commit to spending $1000 on a full differential rebuild.

 

[duderz7]

It's a doable job with enough patience and tools. You'll have to pull the carrier which means pulling the axles as well. Resetting the carrier preload also requires a special tool not many have in the garage. I regeared mine in my driveway, but I bought a bunch of tools I may never use again. Like said above, watch some videos and see how comfortable you are getting into it.

 

[JeepJeepster]

Working on a differential really isnt all that tough, more so if youre just replacing pinion bearings/crush sleeve.

One issue is, to remove the pinion, you must remove the carrier which means you will need to adjust the side adjusters for the carrier preload/backlash. You'll need a dial indicator and the tool (or make one) that goes back in the axle tube to adjust the side adjusters.

Doable in the driveway? Absolutely. The FSM has very clear instructions on how to do this. I 'might' consider just retorqueing the pinion nut before really tearing into it. I recommend using locktite since you've been messing around with it so much. Or get a new nut. The FSM lists a minimum pinon nut torque that you could try first. You cannot just loosen the pinion nut and leave it.

If you did damage the bearings, you have no choice but to replace the bearings and races. If it still rotates smooth after retorquing, the bearings may be ok. If the pinion is notchy when you rotate it, the races are bad. I've personally ruined brand new bearings by using an air hammer to drive the pinion back out to make adjustments... Not fun.

 

[stapleg]

Working on a differential really isnt all that tough, more so if youre just replacing pinion bearings/crush sleeve.

One issue is, to remove the pinion, you must remove the carrier which means you will need to adjust the side adjusters for the carrier preload/backlash. You'll need a dial indicator and the tool (or make one) that goes back in the axle tube to adjust the side adjusters.

Doable in the driveway? Absolutely. The FSM has very clear instructions on how to do this. I 'might' consider just retorqueing the pinion nut before really tearing into it. I recommend using locktite since you've been messing around with it so much. Or get a new nut. The FSM lists a minimum pinon nut torque that you could try first. You cannot just loosen the pinion nut and leave it.

If you did damage the bearings, you have no choice but to replace the bearings and races. If it still rotates smooth after retorquing, the bearings may be ok. If the pinion is notchy when you rotate it, the races are bad. I've personally ruined brand new bearings by using an air hammer to drive the pinion back out to make adjustments... Not fun.

I just went back and retightened the nut a hair past my original dimples with some blue locktite. Checked inch lbs needed to spin the yoke and it was about 20-25. I understand those numbers mean next to nothing since the entire dif is assembled, but it’s definitely on there good now. Didn’t feel notchy thankfully

edit inch lbs not ft lbs lol

 

[eric1514]

I just went back and retightened the nut a hair past my original dimples with some blue locktite. Checked ft lbs needed to spin the yoke and it was about 20-25. I understand those numbers mean next to nothing since the entire dif is assembled, but it’s definitely on there good now. Didn’t feel notchy thankfully

20-25 ft-lbs? Inch-pounds, hopefully.

 

[stapleg]

20-25 ft-lbs? Inch-pounds, hopefully.

OOPS yes that was a typo. It was 20-25 inch pounds. I’m not used to typing inch lbs lol

 

[stapleg]

Update.

As I said, I took the pinion nut back off and re-tightened just past my original dimple with blue locktite. This is about the position the nut was in when I went too far with the impact. Did not check the torque on the pinion nut, its just on there tight with thread locker. Tapped around with a hammer to make sure the bearings and such were seated. Yoke spun just fine, tightened and checked inch pounds until I got about 25. Been driving it around and the sound on decel is no longer there.

Been checking temps on dif cover and yoke, been reading 140-170F and 120-140F respectively. Probably less on the yoke. Seems like normal range maybe. I'm sure the dif is no longer at 100% will never quite be the same, but at least the obvious sounds are gone. And I'll (hopefully) know if the nut ever comes loose if the decel sound comes back over time.