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Hi everyone,
I have a light erratic drumming sound from possibly the right rear. It is random at all speeds but gets a little louder above 40mph. It's not in sync with the speed. Rear brakes, calipers and rotors replaced about 3k ago. I checked torque on leaf spring u bolts, lug nuts and removed lower bolt on the shock to check it, its ok too. Nothing loose or rubbing on exhaust or drive shaft. Differential oil replaced about 3k ago, no metal in it, put in exact manufacturer oil and filled exactly.

Any help is appreciated!

 

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Jack up and rotate wheels by hand. If you hear the noise, try to track it down.

Try to move them in all directions to check for any excess play. If you feel excess play, note the direction of the movement, that will give you the clue.

Check u-joints carefully, and check all fluid levels in the diffs and transfer case.

Could also be tire noise..........................

Thanks!
If there is play in a certain direction what clue is that?
I know how to check for bad wheel bearings but not sure on the diff.

 

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Top to bottom play is slight, enough to say bearing is bad. But pulling the wheel in/out is a good 1/16. Feels real bad, left rear is half as bad as the right going in/out. These are both on rear. Edit: I read 1/16 is ok. But top to bottom has slight movement and along with the noise symptom I guess bearing.
Thanks for staying with me on this.

 

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On BMWs the caliper is bolted tight and the pads wiggle some. On the truck the caliper wiggles some. Is this correct?

 

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You are describing two differing styles of caliper. I'm not a great typist, so here is some info from HAYNES below. My comments are in green.


"There are several types of calipers:

Floating calipers
A floating brake caliper contains a piston on only one side, but has pads that make contact with both sides of the brake disc. The caliper slides back and forth on bushings or pins. When the brakes are applied, the piston pushes the brake pad on the inboard side of the disc. The caliper then slides on the bushings or pins, which squeezes the outboard pad against the rotor, initiating braking action.
This is absolutely the most common type of caliper, with many having two pistons instead of just one. This type of caliper is used on our trucks in front and rear.

Sliding brake calipers
A sliding brake caliper works in much the same way as a floating caliper, but is mounted in a slot in the caliper adapter. When you hit the brakes, it uses its single piston press the inner pad against the rotor, then the movable frame of the caliper applies pressure to the other brake pad, pressing it against the disc.
Rarely used

Fixed brake calipers
A fixed caliper is mounted to a bracket, and as the name suggests it doesn't move. It usually contains two, four, six or even eight pistons. The fixed caliper consists of an equal number of pistons on both the inboard and outboard halves of the caliper. It is generally accepted that these have better performance, but cost more. That's why fixed calipers with multiple pistons tend to be installed on high-performance cars."
Sports cars and high-end tend to use this type of caliper

long story short, bearing oil must have drained back towards the diff after many hours with both axles lifted up. It’s evident now from the sound that the left rear bearing is real bad. Can’t be sure about the right because part of the noise transfers over. Going to have both replaced at the dealer. They don’t gouge here, maybe a hundred extra but worth it.

Thanks for help! It kept me going long enough to find it.

 

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Nice!! Good find, and good luck.

I will add something here that might come in handy. If the bearing(s) are badly worn, there's a good chance the axle might be worn down in that contact area. Thus you'd need a new axle, which would be expensive at the dealer... BUT ...... there are some bearings available that are offset, so that the roller bearings contact a virgin part of the axle, and this way you can confidently use the old axle. If the dealer calls and says "you need two new axles", try and suggest the offset bearings to them.

Please post results when done. 🇺🇲

When I google offset bearings all I’ve found so far is stuff for offset wheels. Have a link?

 

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It's been 20 years since I used them. I just looked, and I can't find them any more. Perhaps discontinued.....

I tried to find a new axle for 2003 GMC 1500 on a GM parts supplier site that I use all the time, but it says 'discontinued', so if your dealer has to install a new axle, it would likely be aftermarket. I looked one up and it wasn't expensive, saw them for $125 to $175 each, not too bad at all. So don't worry about it.

I took it to the dealer since they didn't hose us on the compressor install a few years ago. They said it was the differential and a rebuild is 1500 parts and 2100 labor. I had to pay $150 to go pick it up. I think it's the wheel bearing, so taking it to a private shop that has a 5-star rating. I'm seeing rebuilt axle/diffs for $1100 including shipping in case it's all bad.

 

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So it's $4,000 to rebuild a diff?? Damn!!!!! I recently did complete rebuild on my Roush Mustang Ford 8.8 diff, all new Ford Racing bearings and gears, including new posi-traction unit, about $1,000 for everything, including fluid.

You could buy an entire brand new rear end for that $4k kind of money, LOL.

That rebuilt option seems reasonable. But I'm guessing you'd need to do the install yourself, or pay someone. The install is not difficult, but the age of vehicle would mean rust, which makes the job way tougher. You may end up needing to cut off some parts with grinder or torch.

Good luck, hopefully it IS just a wheel bearing and the private shop can easily fix..........

Does anyone know where to get a trusty complete rebuilt rear end in SC?
I watched a good video on rebuilding the diff and it requires lots of tedious shim measuring and trial fits. A kit the guy used had the wrong bearings and two bearings from different manufacturers measured differently. I don't think anyone will put the time into it other than a rebuild place that does it every day. Jasper was a good place for engines, diffs etc but has racked up a list of complaints in 2022 on BBB.

 

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Does anyone know where to get a trusty complete rebuilt rear end in SC?
I watched a good video on rebuilding the diff and it requires lots of tedious shim measuring and trial fits. A kit the guy used had the wrong bearings and two bearings from different manufacturers measured differently. I don't think anyone will put the time into it other than a rebuild place that does it every day. Jasper was a good place for engines, diffs etc but has racked up a list of complaints in 2022 on BBB.

So it's $4,000 to rebuild a diff?? Damn!!!!! I recently did complete rebuild on my Roush Mustang Ford 8.8 diff, all new Ford Racing bearings and gears, including new posi-traction unit, about $1,000 for everything, including fluid.

You could buy an entire brand new rear end for that $4k kind of money, LOL.

That rebuilt option seems reasonable. But I'm guessing you'd need to do the install yourself, or pay someone. The install is not difficult, but the age of vehicle would mean rust, which makes the job way tougher. You may end up needing to cut off some parts with grinder or torch.

Good luck, hopefully it IS just a wheel bearing and the private shop can easily fix..........

took the diff out, axles had to come out first. The 8mm bolt that holds the large pin in had red loctite, had to cook it good and still on the verge of breaking. Ended up that the left carrier bearing was shot. The Pinion and bearings feel good. Replacing both carrier bearings even though the right one was good. The left one would not pull off, even after cutting the bearing rack and using a propane torch. The right one pulled off with heat and lots of effort. Had to dremel the inner race off the left one. It had Timken bearings in it and same going back. Thanks for the help, it kept me going!
Good reference site:

GM 10-bolt 8.5″ vs 8.6″ (or 8.625″ to be exact)

There is some confusion about what exactly is similar and different between GM 10-bolt 8.5″, 8.6″, and 8.625″ rear axles. First and foremost, 8.6″ is simply another name for (and an easier way of denoting) 8.625″. This means that both 8.6″ and 8.625″ mean the same thing, however people in the...

www.my4by.com

 

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Nice! You did it all yourself? That's what we like to see. Some of this stuff seems like magic, but most of it is common sense and care.

Basically you fixed it with two new carrier bearings?? That's awesome. Kudos to you!

Thanks! Yep, by myself. About to press on new bearings. I have two shim kits coming in case new bearings are off a smidge but I doubt I will need them. I told my wife I’m working like I’m paid by the hour. That’s an old pic google has, haven’t been able to change it or maybe don’t want to 😁 45 there but 62 now, slower going.

 

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Don't feel bad, I'm 72 and still doing this shit, haha. Takes a lot more effort to stay healthy nowadays, that's for sure.

Be careful pressing on bearings, that can be tricky. I wear eye protection and full face guard, just in case anything flies off. Setting pinion depth is tricky too, but you aren't doing that. Take your time getting proper preload on the carrier bearings (determined by shim thickness), along with proper backlash (also determined by shim thickness). It is usually a game of trial and error, often taking multiple attempts (carrier in and out) before all is right.

Ok, I’ve watch 15 YouTubes, it has a real thick shim on both sides, hoping its going to work on backlash and tooth pattern. Got some yellow goo coming. Going to sell this truck, got a Ridgeline that will do more than we need. I always have fixed used cars up real good before selling, then get a real good price too.