Differential or wheel bearing???

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Futzy1

Futzy1

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I'll try to keep this brief. At speeds above 25-30 I get a humming/whirring noise from my rear end. Its speed dependent on both volume and pitch. I'm trying to figure out if it is a wheel bearing or a differential problem.

Thanks as always,
Futzy
 
After a drive, feel your wheel centers. Bad bearings heat up.

You can also jack the car up & try to spin each rear wheel by hand with the car in neutral to note any excess friction.

Just make sure it is safely supported with the front wheels chocked.
 
Checked the fluid in the diff lately? Not trying to be a smart ***. But I would start at with the basics
 
69FBCuda said:
Checked the fluid in the diff lately? Not trying to be a smart ***. But I would start at with the basics
Click to expand...
No jack assery taken. Just checked it last night, and it looked ok. It's part of the reason I posted.
 
Not sure if it matters, but just now on my way home I was doing 40 and popped it into neutral just to see. There was no change in the sound in or out of gear.
 
Ok, I had a 25 minute drive home yesterday and I felt behind both rear wheel drum assemblies. They were both a little hot, but the driver's side was "burn your hand" hot. I'm going to put her up tonight and give the wheels a spin.
 
Futzy1 said:
Ok, I had a 25 minute drive home yesterday and I felt behind both rear wheel drum assemblies. They were both a little hot, but the driver's side was "burn your hand" hot. I'm going to put her up tonight and give the wheels a spin.
Click to expand...

There is an old school trick if you have drum brakes in the back to determine a wheel bearing.
The sound changes when you put the brakes on because the drum brakes try to center the axle taking some of the load off the bearings.
 
Drive about 40 mph swerve the car from side to side maintaining a steady speed . If the sound changes its not the gears and you can look from there.
 
I'm not going to lie. I'm really hoping it's a bearing.
 
Put the rear of the car up on jackstands (do this safely because you'll be under it), start the engine and put it in gear, hopefully both wheels will spin, if not you might have to back off the brake adjustment if one wheel doesn't want to spin freely. Then lay under the car and take a long screwdriver or wooden dowel with one end pressed against your ear and the other end against the suspect bearing, you'll be able to tell if it's a bad wheel bearing or diff bearing by listening to it, one will be louder than the rest.
 
So I've been perusing the manual as to how to replace the bearing. If that's what it turns out to be I know I should replace both sides, but will I also need to replace the collars seal etc, or just the bearings? And how hard are they to get out?
 
Well your hot bearing is a good indication. Unless you have a dragging brake.
I had an off brand a while back, and the nose was a pitted carrier bearing. Not a big deal to replace, but it was on a hoist. And once carrier was out,the pitting was easily noticeable.
Outer bearings are flat rollers, you should be able to see the wear. If i recall, there are axle repair bearings available if your axle is scored.

I have a 7.25 to do in a few weeks too. Its out and on a stand so its easier to do.
I plan to pull it apart, then order the necessary bits.
 
Tooljunkie said:
Well your hot bearing is a good indication. Unless you have a dragging brake.
Click to expand...
I'm fairly certain it's not the drum. I rebuilt those right when I got the car, and I'm not getting any of the normal symptoms. I've just always assumed that the rear end noise was the diff, until I read something recently that made me check into the wheel bearings.
Tooljunkie said:
have a 7.25 to do in a few weeks too. Its out and on a stand so its easier to do.
I plan to pull it apart, then order the necessary bits.
Click to expand...
Take lots of pics for me???
 
Post #8 is right on the money. Swerve the car strongly from left to right at about 40. If the noise changes, it is the wheel bearings.
 
Well that was the plan, but it rained here in the desert for the first time in months, so I figured it wouldn't be the best time to test the questionable rear end on a 50 year old car. Lol.

HOWEVER!!!

I finally had a minute, so I did what I should have done in the first place. Chocked up the front, raised the rear and gave that hot wheel a spin. Even a lay mechanic like me can tell. . . .that dont sound right

 
So I'm looking at my manual. I know that with most pressed bearings you need to remove the shaft, and that to do so there is a pin in the differential and sometimes a c clip. I'm not seeing anything about getting into the dizzy at all on this. Am I missing something?
Screenshot_20180504-141738_Adobe Acrobat.jpg
 
It is a pressed on bearing with a lock collar. It is held in at the axle housing with nuts and bolts. Also it would be a good idea to replace the axle tube seal at the same time.
 
Basically you cut the bearing off the axle,without damaging retainer or axle.
Then warm up new bearing in oil while chilling axle in freezer. Then drop retainer,bearing and collar and seating it with a long piece of pipe.
Whole method changes with a press.
 
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