Rear Axle Bearing Tolerance

slamkeys · December 8, 2007

Has anyone replaced the axle bearings on a 2002 Yukon (or equivalent)?

I replaced my parking brakes a couple weeks ago and noticed that there was quite a bit of play in the axle bearings (84K miles). I just bought the SUV second-hand (2WD) and I don't know if it was ever driven through high water or not, but it would'nt be unusual for that to happen here in Hurricane town - Houston.

I don't have any speed-related bearing noises, but I do think there is too much noise when I drive over bumps and potholes.

What I need to know is how to reliably check the rear axle bearings, and if replacement is needed, is it possible that the shafts could be worn as well? Is there a race on the shafts or do the bearings ride directly on the shafts?

I've been researching the bearing replacement job online and in my manuals, but have yet to see any good pictures of what the bearings and the shaft will look like when I pull them out. If anyone has any pics I'd like to see them.

Thanks

pm26 · December 8, 2007

Atypical GM rear solid axle will have its outer bearings pressed into the axle housing (=interference fit). Outside the bearing will be an oil seal. You pull the axle shafts by removing the differential cover, rotating the axles until you see a pin, which you need to remove. Then you will see C clips which retains each axle laterally inside the differential assembly. You must pull each C clip out and then you can pull each axle straight out. The differential has a side carrier bearing for the axle shaft as well.

The bearings are tapered roller bearings because they must resist both the radial forces and lateral forces. Typically, the axle will fit snug into the bearing inner race (=slip fit) and there should not be much play. When you jack up the rear wheels and rotate them, do you see any up and down movement? What kind of play are you talking about? There is some lateral play, as when trying to pull a wheel straight out, because the C clip is what retain the axle in, and the pin prevents the ends of axles from being pushed in. There is some amount of play there and it is normal.

hubbycap · December 8, 2007

Yeah, just like pm26 sez. Anectdotally, I had my GMT900 (6K miles) rear jacked up yesterday and I noticed lateral (pull straight out) play that was roughly equivelent to the play on my '95 C1500 with 346K miles. Just a little bump with push/pull of the free wheel.

slamkeys · December 11, 2007

So, the bearing rides directly on the axle? That means there must be a taper on the axle itself?

I don't notice the play when I have the wheels installed, but when I had the brakes and the discs removed, I could move the hubs (both sides) up and down a little bit. The end play was what I would expect, just a little in/out movement.

I'm guessing that when I put the brakes back on they pushed the axles deeper into the taper, removing the play. Does that seem feasible?

What's the easiest way to diagnose this type of bearing?

FYI - I have the limited-slip diff, which according to my manuals requires a little extra fudging to get the c-clips aligned before you can pull out the shafts.

Westlotorn · December 4, 2008

On the 1/2 Ton GM rear ends the Rear Wheel bearing is a cylindrical design. No Taper at all. The only thing keeping the axle in place is the C clip and the Brake if you have Disc brakes in the rear. Wire up the disc brake caliper when you remove it to keep from damaging the brake hose. FYI after removing the pin retainer bolt, 8mm inside the differential and taking out the pin it is necessary to manually push the axles in towards the middle of the car to gain access to the C clips. As you rotate the driveshaft by hand you will see a window in the Ring and Pinion carrier that gives you visual access to the axles and C clips. Use a magnet to pull the C clips out and once you slide the axles out don't rotate the drive shaft at all until the axles are back in place. You can pick up an inexpensive axle bearing puller ( harbor freight) $10.00 or so and it does a fine job pulling the bearing out of the housing for replacement. If the axle shaft is blued and damaged where the bearing rides it needs to be replaced. The blueing is from heat while rotating on a failing bearing. The blue area is now a weak point that can cause axle fracture. I have a friend who almost died in a roll over caused by running a damaged axle. When it snaps the wheel can leave the vehicle.

After reinstalling the axle shaft and the C clips it is necessary to pull the axle out as far as possible to make room for the locking pin to be reinstalled. Make sure you use a quality brand of lock tite on the threads to make sure this never comes loose while you are driving.

Use a new axle seal, if you re use an old seal and it leaks you not only have to fix the seal but also replace the brakes from the oil leakage. A new seal is only $10. not worth the risk.

All this is very simple actually and can be completed with both bearings changed in an hour or so. Most of your time will be spent preping the Differential cover for a new gasket or silicone sealer. Your choice which to use.

mkory · September 15, 2009

Bump. I have just replaced the front bearings, and the ride is so much quieter than before that I never noticed this "new" noise. It might just be tire noise, but it could be in the rear end. How do I diagnose a rear wheel bearing without tearing everything apart?

The noise is very faint and only heard on very smooth asphalt around 50mph.

mkory · September 16, 2009

Bump.

awalkertx · August 24, 2011

Guys,

I'm stuck in a bind right now.

Background: '03 k1500 tahoe replacing the rear outer axle bearings. This all came about when doing the emergency brakes and noticing a bad oil seal on the passenger side and 2mm of in/out play on the right side axle.

I've got it all apart, and now I'm having some hard times getting the new bearings installed. The replacements are TIMKIN one-piece bearing and oil seal. I'm installing with the method of a super large socket on the race and a big hammer. Any suggestions?

Thanks for any help/advice you can provide!!

Adam

jblakeney · August 24, 2011

Guys,

I'm stuck in a bind right now.

Background: '03 k1500 tahoe replacing the rear outer axle bearings. This all came about when doing the emergency brakes and noticing a bad oil seal on the passenger side and 2mm of in/out play on the right side axle.

I've got it all apart, and now I'm having some hard times getting the new bearings installed. The replacements are TIMKIN one-piece bearing and oil seal. I'm installing with the method of a super large socket on the race and a big hammer. Any suggestions?

Thanks for any help/advice you can provide!!

Adam

It needs to be pressed in. NOT HAMMERED on....... You probably will damage the bearing if you hammer it on. Take it to a machine shop and have the new one pressed on, I am assuming you already hammered the old one off or did it slip off? If it slipped you need a repair bearing not the stock bearing.

Jbo

pm26 · August 25, 2011

How can you press in the bearings into the rear axle housing without removing the housing itself? The bearings are interference fitted inside the axle housing itself, not on the axle shaft. The axle itself is a slip fit into the bearing once pressed in. I remember correctly, it is safe to hammer in the bearings provided you have a properly fitting socket or a piece of PVC pipe that will ride on the OUTER race of the bearing. Do not attempt to force the bearing in by pushing on the INNER race, or you will destroy the bearing. By "hammering" I mean gently pounding the bearings in by the OUTER race. Grease the bearing outer race liberally before installation. Grease the bearing rollers too to protect the bearing, as it will take a while for the differential oil to reach them. I watched a mechanic replace the rear axle bearings and seals on my 1977 Camaro many years ago and that's what he did.

Note: in my previous post I assumed these bearings are tapered roller bearings. I confused them with the front bearings, which are in fact tapered rollers. The rear ones do not have tapered rollers, only straight rollers, because all axial forces are captured by the C clips and the differential pin, not the bearing itself. The rear bearings are loaded only radially (i.e. up and down motion of the axle shaft. Axial loading is in and out motion.

On some Fords, like my 1967 Thunderbird, the rear axle bearings are pressed onto the axle shafts, not inside the axle housing. The interference fit of the bearing is what keeps the axle shaft secure, as there are no C clips inside the differential holding the axles in. To install the bearings on the axle shafts, you would obviously press them on by the INNER races, and this can be done in a hydraulic press, as axles are removable and not that large.

Also, the axle play is not in the bearings, only in radial direction and that is fixed by the construction of the bearing itself (play between the rollers and races). The axial play(moving wheel in and out when pulling on it) is between the C clips and the differential pin, not the bearings.

Doug_Scott · August 25, 2011

If you drive the new bearing in with a socket, make sure that the socket does not impact the seal. You can use the old bearing sometimes to drive the new bearing back in. Make sure that the just the outer race impacts the new bearing. You will also want to make sure that you do not drive the old bearing in too far into the housing. Sometimes you can't get the old bearing back out again.

Any rear end that uses the removable centre section (sometimes called a "pumpkin") will have the axle bearings pressed onto the axle shaft. The reason for this is quite simple, you cannot get the diff housing out with the axles in, so the axle bearing is what holds the axle in the rear end housing.

ChevyTech77 · August 25, 2011

How can you press in the bearings into the rear axle housing without removing the housing itself? The bearings are interference fitted inside the axle housing itself, not on the axle shaft. The axle itself is a slip fit into the bearing once pressed in.

It's that Napa schooling.

Any rear end that uses the removable centre section (sometimes called a "pumpkin") will have the axle bearings pressed onto the axle shaft. The reason for this is quite simple, you cannot get the diff housing out with the axles in, so the axle bearing is what holds the axle in the rear end housing.

There are other axles with pressed on axle bearings as well. Like a few of the Dana rear axles used in Jeeps.

pm26 · August 25, 2011

If you drive the new bearing in with a socket, make sure that the socket does not impact the seal.

What do you mean by that? You must first remove the oil seal to get to the bearing, then remove the bearing, drive in the new bearing, then drive in the new oil seal. Are these trucks any different from GM rear wheel drive cars of the past?

jblakeney · August 25, 2011

Oops, forgot C clipped axle not plate retained. Some of us work on more than one brand.

Slide hammmer removal. Bump in. With race installer or large socket.

Note I was wrong and stand corrected. The ones I work on usually have the plate.... not the c clip.

Somebody needs the chip off there shoulder.

Jbo

pm26 · August 25, 2011

Oops, forgot C clipped axle not plate retained. Some of us work on more than one brand.

Slide hammmer removal. Bump in. With race installer or large socket.

Note I was wrong and stand corrected. The ones I work on usually have the plate.... not the c clip.

Somebody needs the chip off there shoulder.

Jbo

My '67 T bird has the bearings pressed onto the axle shafts and a retainer plate. There is also a retaining collar pressed on right next to the bearing on the inboard side to provide additional retention for the axle. As a matter of fact, I have new bearings that I need to install on that car's axle shafts.