Rear axle noise.

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luxstang

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Can a differential make the same noise as a bad wheel bearing?

My rear axle makes a rhythmic "crunching" whirring noise that changes amplitude with the speed of the car just like a bad wheel bearing.

We replaced the wheel bearings a few weeks ago and in fact there was one that was shot and made an audible noise when we turned it by hand after the axle was out of the car.

We put new bearings on and the noise was still there.

It's even getting more and more prominent.

Could it be the rear end? The noise was there (though hardly audible) after I put the new 3.8:1 in but I thought at the time that I had damaged the wheel bearing while struggling to get one of the axles back in.

The oil level in the differential is correct btw.

So, can a rear end make a noise like a bad wheel bearing?

 
Can a differential make the same noise as a bad wheel bearing?

My rear axle makes a rhythmic "crunching" whirring noise that changes amplitude with the speed of the car just like a bad wheel bearing.

We replaced the wheel bearings a few weeks ago and in fact there was one that was shot and made an audible noise when we turned it by hand after the axle was out of the car.

We put new bearings on and the noise was still there.

It's even getting more and more prominent.

Could it be the rear end? The noise was there (though hardly audible) after I put the new 3.8:1 in but I thought at the time that I had damaged the wheel bearing while struggling to get one of the axles back in.

The oil level in the differential is correct btw.

So, can a rear end make a noise like a bad wheel bearing?
Mike

some new bearings are crap out of the box.

from where did you get the new bearings and which brand did you order?

Cheers

Frank

 
Yes, a rear end can make similar noise to a failing wheel bearing. Since it's the first step in removing the rear assembly, you might as well pull the axles and re-check the new bearings. Easy to do, just be careful not to hurt the axle seals. If they are good, the obvious next step is to remove the assembly to find the issue.

If that's a newly built rear end, something may have not been set up properly during the build.

 
If the differential bearings are bad enough to make noise the pinion seal will usually be leaking or there will be noticeable play in the yoke if it's the pinion bearing. If it's the carrier bearings there will usually be a lot of backlash. There will most times also be a whining noise and clunking. The noise will also change depending on whether you are accelerating or decelerating or coasting.

I agree with Mike about the new bearings being bad, even we'll known name brand items. That particular noise that rear wheel bearings make is a combination of being dry and wear. Because the loaded car is always on the wheel bearing it will make the noise continuously, with little change when accelerating, decelerating, or coasting.

If you have an open differential you should be able to jack up one side at a time and isolate the noise location.

 
I won't go over all the explanations but Pinion bearing will roar or make noise like the axle. Carrier like stated causes excess gear clearance and will clunk more.

You said one axle will difficult to get in. They should just slide right in. Be sure and clean all rust out of bore in the axle housing and check for any damage from maybe pulling the seal. When they install the bearings it is very important that they not press on the outer race only the inner race. Press the bearing on first using a piece of pipe that fits over the axle and only hits the inner race then press the retaining ring on.

I personally have never had any issue with new bearings being bad only damaged by installer. They are produced to tolerances within millionths of an inch. My uncle worked at Timken bearing for many years and I toured the plant. Everything is done automatic so no human error. All balls and races are checked automatic no human interaction. The Chinese shops have better equipment than U.S. the steel would be the question there. Timken in Canto Ohio use to make their own steel. During WWII they made 50 caliber machine guns. They came up with process to hot pierce the bore into the barrel. Got off subject.

If you have a mechanics stethoscope you can put the car on jack stands or on lift and run in gear and listen to each bearing. Use brake to put load on the gears.

 
When you were turning the axle after bearing replacement was your driveshaft turning? There is a small chance it could be the u-joints on your driveshaft.

It is entirely possible that your 3rd member needs to be pulled and set up again with new bearings.

I'm curious what you will find.

 
Thanks for your replies.

When we changed the bearings a few weeks ago the axles did slide right in. I only had a problem with one when I did the differential but I was overworked and running out of patience.

The rear end is a locking one, True Track and it was a completely new piece set up by a specialized speed shop.

It'll take a few weeks before I can look into it in detail.

Ill keep you posted.

 
Mike your getting great advice. How old are the tires. Did you put on your other set and see if it's the tires?
It's not the tires. It's definitely a noise caused by something hard, like metal. Not the softer noise rubber makes.

Btw, it started when I put the new differential in and it got worse from there. When the differential came in, the car had the 18s on and the noise was there. It's been on Magnums for about a year now and the noise is still there, so we can rule that out, I think.

Oh, I checked and there is no leak whatsoever on the rear end.

 
It's a True Track, so it shouldn't need friction modifier as they don't have clutch plates.

The shop told me the same thing.

I'm gonna give them a call and see what they say.

 
So you have a Locker.

All Locker's sound like that ::thumb::

mike
Yeah... not so much. Properly installed, the lockers can make clunking/popping noises when going around corners - but straight-line driving shouldn't make any more noise than you would expect a standard non-locking differential.

Lockers also tend to get quieter and they wear-in, not progressively worse.

I think you need to pull it, inspect all the bearings (inner, outer, and pinion), check the gear lash, and make sure the resistance and end-play on the pinion is correct.

 
The true trac is not a locker. It is a torque biasing diff. Kinda looks like a pencil sharpener inside. It should be quiet, and work like magic. It is kind of a clutch less limited slip, on the the original makers of that design was Quaife. Google it and take a look, it is pretty neat how they work. That is the same setup under mine, and I have one under my pickup. Couldn't be happier with the true trac.

My wild guess is incorrect setup or driveshaft u-joints.

 
Again thanks guys. U-joints might be worth considering...

When I get the opportunity to dig into it, I will work the list. U joints, (new) wheel bearings, rear end etc.

 
still could be a u-joint if the bolts were tightened down too far or if a roller had fallen out or gotten damaged.

I'd start off with a good inspection looking for any signs or rubbing on the driveshaft from a cable, exhaust, etc also if a disc brake conversion look at everything clearance wise.

I'd then undo the driveshaft at the pinion yoke and inspect the u joint for damage, roughness, signs of heat-if it looks good, move to the slip yoke side and go ahead and pull it and repeat. (Yeah you may lose some fluid, but sometimes you have to make a mess.)

If you still have not found it, put one wheel back on and spin the rear end while the driveshaft is disconnected and feel for roughness. If none is found, repeat on other side.

I would certainly check the axle bearings before pulling the chunk to see if they might have been pressed on improperly

I had something similar after getting my disc brake conversion. They left the retainer plates on rather than pulling and replacing the wheel bearings (or cutting the plates off) as they assembled it, it made noise, until I tore it down and did it right.

 
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