Rear End Gear Whine on Decel

[TwinStick]

I'm probably going to answer my own question here, but I'd like some input.

I recently swapped my '04 2-piece driveshaft to the newer 1-piece aluminum shaft and 1480 series yoke. Per instructions, I counted the threads on the pinion nut before removing the old yoke and then I tightened the new pinion nut to the same depth. Now I have a pretty low level, but noticeable gear whine under decel. I'm thinking maybe I tightened the nut a little too much and that gave me some slop between the pinion and ring gears...maybe.

Could it be that the 1-piece aluminum shaft is just better at transferring a gear whine that's always been there?

The pinion gear is shimmed when setting backlash, correct?

Can I just loosen the pinion nut by 1/2 turn and test drive it, or will that even matter? If it's overtight the shims would have crushed some and won't go back to original depth, or will they?

It could probably use a freshening up anyway, but that's a cost I don't want to pay right now. Could it hurt anything to try loosening the pinion nut?


Thanks in advance!

 

[THEFERMANATOR]

Whoever told you to count the threads gave you bad advice. Pinion preload is set by torquing the pinion nut to crush a crush sleeve. Whenever you have to remove the yoke for any reason, there is a torque spec to set the pinion nut back to that holds everything tight without crushing the crush sleeve anymore(it takes x amount of torque to crush one). You're always supposed to retorque them using a new nut. Loosening the nut is a great way to TRASH your ring and pinion as well as pinion bearings by letti,g the pinion walk and move around in the pinion bearings. Sounds to me like you messedup putting your yoke on, and trashed some bearings, maybe even your ring and pinion. You're going to have to COMPLETELY disassemblethe diff, inspect it, and repair as neccesary. If you're lucky new bearings and a mesh change will quieten it down, otherwiseplan on a new ring and pinion too. Differentials is one item that isvery simple, but if you don't know exactly what you're doing AND have the tools to work on them, leave them alone. I've seen more diffs trashed by guys doing pinion seals and not setting them back up correctly than anything else.

 

[bmc1025]

Whatever you do, do not loosen up the pinion nut. Once the sleeve is crushed too far you have to start over with a new one.

 

[Awenta]

I doubt you crushed it. It takes some effort to crush these. My guess is it was too loose. Time to look inside like ferm said.


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[2004LB7]

The pinion depth shouldn't change with the nut torque.

The pinion depth is ditermined by the shims. The crush sleeve is used to preload the bearings.

Counting the treads to put it back can work but not often as you should replace the nut each time it is removed. The new nut may not sit the same as the old one with the same number of rotations causing a diferance in bearing preload.

You may be able to get away with torquing it down a smidge more crushing the sleeve a tiny bit but you have to use the "used brearing" preload amount.

Like the ferm said, best to take it apairt and inspect everything.

 

[TwinStick]

Sounds fantastic. Alright. Inspection time. What am I looking for other than uneven wear on the ring/pinion? How do I know the torque it is supposed to be tightened to? Sounds like I may just need to take it to take it to the shop I use and trust.

 

[2004LB7]

Pinion preload for used bearing is between 10 & 20 lnch lbs. Without the carrier/ring gear in place

 

[2004LB7]

Check for the posibility of a second wear pattern developing. Excessive metal on the drain plug. Pull the axles and drive shaft and feel how the gears mesh and smoothness of the bearings, etc.

 

[THEFERMANATOR]

Pinion preload for used bearing is between 10 & 20 lnch lbs. Without the carrier/ring gear in place

Not preload, rotational force. Once they start making noise, you're best to pull it all down, inspect, and repair as neccesary. If you don't know how to build one, then find somebody who does. Diff's are pretty simple, but knowi,g how to set one up is critical. If you mess up setting your pinion depth, I've literally seen them weld themselves together, and rip the teeth off the pinion(made a NASTY mess of that 12 bolt). From the sounds of it, you need to find somebody to fix it and hope your ring and pinion is still useable, or find a used rear axle, and if it needs a yoke change, have somebody do it that has a torque wrench to properly tighten the pinion nut.

 

[clrussell]

I doubt you crushed it. It takes some effort to crush these. My guess is it was too loose. Time to look inside like ferm said.


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This.. I'd almost say tighten it more.. it takes ALOT to crush the sleeve.. I generally just run the nut back down with loctite and a air gun until it stops.. my air gun doesn't have enough ass to crush the sleeve anymore, and it's a good airgun.


Take the driveshaft off and turn the yoke by hand.. if you feel excess slop tighten the nut more.

If you can turn the nut without a large cheater pipe it's probably not tight enough

 

[2004LB7]

This.. I'd almost say tighten it more.. it takes ALOT to crush the sleeve.. I generally just run the nut back down with loctite and a air gun until it stops.. my air gun doesn't have enough ass to crush the sleeve anymore, and it's a good airgun.


Take the driveshaft off and turn the yoke by hand.. if you feel excess slop tighten the nut more.

If you can turn the nut without a large cheater pipe it's probably not tight enough

2x

At this point, there is not much to loose tightening the nut 1/16th to 1/8th more and see how it is

 

[PureHybrid]

I agree that it's probably not overtorqued. I was groaning on my 3ft 3/4" bar to get my pinion nut loose.

If in doubt, just pull the rear cover, check backlash and the wear pattern as well as rotational torque.

 

[2004LB7]

When I did my rear end I had to use a 24" - 3/4"beaker bar and a jack to lift / turn the beaker bar it was that hard. Getting it off wasn't too bad but crushing the sleeve was likely several hundred foot lbs. My 1/2" impact wrench wouldn't even come close to budging it at it is supposedly rated at over 700 foot lbs.

 

[TheBac]

Moved over to Axles/TC section.

 

[Hnkstang50]

As said there is no torque spec for the pinion nut due to setting the bearing preload with the crush washer. There is a turning torque spec to get the preload on the bearings correct but the ring gear needs to be removed to check that. I know some manufacturers have a different spec for new or used bearings.

I work at a BMW dealer and the repair instructions for changing a pinion seal is to mark the nut and the pinion with a punch and put the nut to the exact same spot lining up the punch marks. This is the method you needed to use with the yoke installed. I usually make paint marks ( just remember not to wipe them off).

As said doubtful you crushed the washer any. I would bet the nut is too loose or the aluminum drive shaft might be making a whine louder that was already there. I'm also thinking if the new yoke was thicker or thinner marking it or counting threads wouldn't work at all. Definitely make sure the nut is tight.

 

[TwinStick]

I'll definitely try tightening it. I have a weak ass 1/2" drive impact running off a 30yr old compressor through a 3/8" hose. That got it to the same thread count as before. This is using a new pinion nut, BTW. I can definitely get it tighter with a cheater bar.

 

[2004LB7]

Good point on the yoke thickness. That one is easy to miss

 

[TwinStick]

I should stick to working on race bikes.

 

[TwinStick]

Well, no more whine after tightening the pinion nut about 1/2 turn with a cheater bar. No visible damage to the internals. Thanks, Ya'll. Saved my ass again.

 

[Hnkstang50]

Glad to hear the noise went away. Just curious did the new nut have that dry lock tight already on it. I know the older Ford nuts do and it threads on kina tight the whole Way so it's hard to tell when all the gap is taken up.