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Discussion Starter · #1 ·
I needed to replace the pinion shaft (part that connects to the ujoints at the rear of the driveshaft...so everyone knows what I mean). I got the old one off, put on a new one (and new seal) and now the rear gears are howling like crazy. When I accelerate, they are quiet. When I'm off the gas or rolling in neutral, it's whirring and howling. Sound level is directly proportional to speed...more MPH = more howl. I'm worried a bearing or something is pinched or ??? Gears / axle was 100% OK before replacing the part (no noise at all - needed to replace it because a corner where u-bolt tightens down on u-joint was cracked, and rewelded by previous owner). :: ANY IDEAS ?!?! I'm scared to drive it.
 

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When you put the new yoke on the rear end did you torque it to correct torque? If you over torqued it you may have crushed the crush collar and have bearings to tight. If you did not torque it enough the pinion may be moving front to back. The main problem with gears is once they start to make noise you can not get it out.
 

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What did you torque the nut to? The pinion shaft nut is supposed to be torqued to a minimum of 175 lbs to properly set the bearing preload. Sounds like yours was changed, and is now either too loose, or too tight. If you torqued it down too much, you have a problem, as the collapsible spacer will need to be replaced. Art and I got into a discussion on this same topic very recently.
 
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Discussion Starter · #4 ·
I used an air gun to crank it down. I didn't think the spec had to be that precise. Is there a way to tell from the fact that it is only on deceleration where the problem is (too tight/too loose)? I'll check the front-to-back play.

I've driven it around the block...so it hasn't gone too far. The crushable piece/spacer...is that something I can get to without dropping the whole 3rd-member?
 

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I'm doing a bit of speculating here, but as I see it:

If you got it too loose, it could throw the lash off on the pinion gear. IIRC, if the ring gear and pinion are too loose, they will make a noise on deceleration. If they are too tight, they make a noise when accelerating.

The tqe on the pinion shaft nut is to set the preload on the bearing. If there is some play there, over/under torquing the nut may alter lash enough to make the noise. Then again, if it's too tight, it might put severe stress on the bearing, and that may be what you're hearing. I'd attempt to check tqe before tightening it any more. It should be a minimum of 175 ft lbs.

But, I'm not a rear end guy, at least not differentials. :) Maybe camachinist, or another differential guru, will pick up on this and clear up a lot of questions with some solid knowledge. This is no time to forge ahead without fear of good judgment.
 

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If you used an impact wrench on it my guess is you have it to tight and crushed the crush collar making the bearings to tight. When I set up a set of gears I always install a solid collar rather than a crush collar to prevent this from happening. I hate impact wrenchs on rear ends. 3rd member will have to come out to be repaired so all settings can be checked.
 
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Discussion Starter · #7 ·
I used an impact gun, but I didn't just thwack away at it until it stopped. I saw how far the old yoke had slid in, and just tried to get it as close as possible. The impact I have was not set all the way up either.

I'll check the front-to-back, and try the torque-wrench (although it only goes to 160 or so).

I get the point about your prior emails though...with the crush collar "crushed" from the original yoke, I need to be able to tighten things up to take out the slop and if I can't get it to 175, then the collar is no good.

From the diagrams I see, I can't tell if I can pull just the yoke to install a new crush collar, or if not, can I pull just the pinion cover (shaft/bearing/yoke and all)...or is it as bad an yanking out the entire pumpkin??

I can't thank you guys enough...you've been a ton of help!
 
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