Adventures in Bearing Replacement

brainpause · August 5, 2024

2002 Sierra 2500 HD with 8.1/Allison.

Back in January 2024, I had to have my left rear bearing seal replaced. I was out of town and didn't have any tools with me so I had to go to a local mechanic that had a good reputation. To my knowledge they only replaced the seal but not the bearings. Topped off the diff fluid. Towed my camper 2 hours at interstate speed with no issues.

I've only driven the truck 2,000 miles since January, and one short 20 mi trip Towing my travel trailer. That was in June. Got to the campground and my left rear wheel was smoking just like it was in January. Called a mobile mechanic, also with a good reputation. He replaced the inner seal again and asked me if I wanted the bearings replaced. I told him if it needed to be done go ahead. Well, he didn't.

I decided the root cause of two failures in 6 months could be bad bearings so I decided to take the job on myself today. And now I have questions. Some of the videos didn't show some specific things that I encountered.

When I took the Hub off, the axle end near the brake plate (behind the disc) had a bit of rust on it but I was able to shine it up with some fine sandpaper. I suspect this could be the root problem also, but who knows. It's hard to tell but I think that's where the rear seal sits when the Hub is installed. Anyway, I feel like I took care of that issue.

When I installed the inner race, I took it down all the way to the lip so that it bottomed out. I'm fairly certain that that is correct based on videos. And the bearing just drops right in there.

1) So here's my first question I guess. Even after putting the rear seal in place, and I assume the seal is supposed to be flush with the rear of the Hub, the inner bearing just sort of rattles around in there loosey-goosey. When I installed it back on the axle, there was little to no play. I just want some assurance that that is correct. The bearings/hub turned fine.

2) I used a new flange gasket when I reinstalled the axle but I didn't use any sort of gasket maker or sealant. The previous repairs did and it was sort of a mess but not terrible. Maybe I should have? I've torqued the axle nuts to 115 ft-lb as is apparently the spec. Should I have used sealant or gasket maker or something in addition to the flange gasket?

It was very hot and humid here today so I didn't feel like test driving when I got done to see if there was any weird noises or grinding or fluids exiting the premises. And yes I also topped off the diff fluid.

I need this truck to be Dependable because we use it to go on camping trips and this left rear axle has my anxiety level raised significantly.

Larry

Edited August 5, 2024 by brainpause

brainpause · August 7, 2024

Nobody?

davester · May 28, 2025

On 8/7/2024 at 6:05 AM, brainpause said:

Nobody?

I know this is an older post but:

1) yes, the inner bearing is loose in the hub. It goes against a machined ridge on the axle, that sets the location of the hub relative to the axle. The inner seal has a lip that goes against the hub.

2) no, I haven't used rtv or any sealant for the axle flange gasket. I have new ones, but I've only had to replace the original ones, that for whatever reason, the p.o. treated like crap and were ripped. For my '04 3500, I've re-used the gaskets more than 10 times, probably now more than 20, and they don't leak. No sealant applied, just wipe oil off the gasket, and both surfaces, then bolt it together.

And I always have some anxiety over the rear inner hub seals, as it's always a crapshoot if and how long they seal for. Sometimes they've failed right away, sometimes after a couple of months, sometimes they last years. They seem to be lasting longer since I made a big seal driver for installing them (vs hammering them in going around the edge), but I haven't been precisely tracking this, more a feeling, it might just be because I have more experience w doing the job.

You just need to regularly check to see if oil is leaking out, and replace it when you notice. I keep extra seals and parking brake shoes on hand, just for when they do fail.