differential bearing replacement

[f.forney]

opened up the differential cover (dumb move) and don't have a clue of where to start ...
wanted to check the bearings inside...
...cant find a diagram online or at the parts stores...
had a high pitched sound the increased with speed (also sounded like a mini rumble strip, or flat spots on bearings? when going slow), not with gear change ...
started on the right rear bearings, they looked ok, the inner seal was intact and didn't appear to be leaking but needs replaced as it isn't one whole piece...
plenty of fluid in the differential...
...any tips or instruction...
...would love to just take it to the shop, just don't have the time or money for the truck to be out of service

[JohnC]

Any metal bits in the diff? Pinion bearings can make that kind of sound...

[f.forney]

no metal shavings, didn't get into the left axle yet (on the road now, response time may be long or short)...
put it back together after doing the right side, same as before...
and thanks for the reply

[Mark Rinker]

My 2002 had a seal go and was run dangerously low on fluid. Noise started about the same time, I was prepared to replace the rear end entirely, assuming we had done damage to the gearset.

Drove it for tens of thousands of miles with a whine that everyone driving the truck got used to. Then, the seal started leaking again! This time, another (GM) shop did the seal and the pinion bearing.


NOISE GONE!!! :D


Sold that truck at 290K...still going strong...

[f.forney]

Pinion bearing is where the drive shaft connects to the differential, right?

Gotta take the rear apart to replace that pinion bearing , eh?

M R, if your pinion bearing went to pieces before that seal started leaking again, couldn't it have ruined the differential gears and or other inner parts?

[rapidoxidationman]

An F150 I had years ago (before I learned the glory of the diesel) had a pinion bearing go bad in the rear end and it was not hard to replace nor did it trash the other bearings in the diff. The toughest part was compressing the crush washer that preloads the bearing the proper amount - overdo it and the bearing is pinched too tight resulting in premature failure. Moving the ring gear, spider gears, shims, and bearings out of the way was pretty straightforward. Can't imagine the Chevy rear end is that much different...

Cleaning out the case after the rebuild (or before) would prolly be a good idea.

[JohnC]

Doing it really right requires knowing how to set up a ring and pinion set. You can probably get away with putting it back using the same shims, but it probably won't be "right". It may be noisy or it may wear faster. In addition, if the old bearings are really bad you may already have abnormal wear on the ring and pinion which bearing replacement won't correct.

I'd at least want to check the contact pattern after replacing the bearings (and correct it if warranted). The sooner you fix it the less chance of collateral damage.

[f.forney]

Ok JohnC, M R, and rapidoxidationman, did a diff before in a 1989 C1500 and the inner parts look alot different, guess I am getting cold feet...

Will have to park it and save up for the repair I suppose...

Will have to look at the left side axle bearings yet...

Any other tips ?

[rapidoxidationman]

Yup: If you're going to do it yourself then either spend the money on the paper manual or subscribe to AlldataDIY so you have the proper procedure to do the job and don't end up handing a mechanic a basket of parts. Mechanics HATE baskets of parts... :)

[JohnC]

Which axle are we talking about?

[f.forney]

Mr. JohnC
Left rear axle, already did the right rear, looked ok except the inner seal ... metal lip separated from the rubber ...
no evidence of leakage...

[JohnC]

Sorry, I mean like, is it a 10.5" full floating axle, or...???
(If it's a Duramax, it should be an 11.5" axle).

[cowboywildbill]

It's pretty common for that seal to seperate when you pull it out. Make sure you replace it with a new one.

[DmaxMaverick]

I'm trying to get a grasp on what you're doing, and why. Seems perhaps terminology is getting in the way.....

The "diff bearings" are the carrier bearings. If you suspect these are bad, the rear end needs a complete overhaul. All bearings, seals, and perhaps a gear set. They don't fail all by themselves. I suppose it could happen, but it's so remotely rare, it just doesn't.

The axle/hub bearings are inside the hubs, at the outer ends of the axle. These are a less uncommon failure, but still rare. If you have a hub seal leaking (behind the wheel), the bearings may be suspect, but it's usually only the seal or spindle sealing surface at fault. You can use a "Speedy-Sleeve" to repair the axle spindle, which allows the seal to have a good surface to seal against.

If you are chasing a noise or vibration, and have narrowed it down to the rear diff, the most likely suspect is the pinion bearing. The pinion seal will usually begin to leak soon after the bearing goes away. If you catch this one early, the likelihood of damage to the remainder of the axle is minimal.

[f.forney]

Got more than two people telling me it is probably the drive shaft bearing (forward of the midway universal joint)...

Sounds like a relatively inexpensive fix if it eliminates the symptoms explained in my previous posts...

mini rumble strip like noise/feeling at low speed, 0-10 mph and a humming noise that increases with speed (and the noise spikes when you hit a bump or dip in the road)....

thanks for all the replies thus far...

I think its 11.5 JohnC, still gotta check with the dealer...not trusting the chain parts stores as much as they sold me the wrong size diff gasket, Had to make my own.

[DmaxMaverick]

2-Piece drive shaft???

Well, that's a piece of important information. The carrier bearing and isolator (located between the 2 shafts, mounted to a crossmember) fail, and can cause several NVH and drivability issues. If you have one with over 50K miles and a vibration issue, that's probably the suspect.

Please, do yourself a favor, and help those trying to help you, and fill out your signature with your truck information. Had we known more about your truck, we would have gone right to the problem.

[f.forney]

Sorry Mr. DmaxMaverick, wasn't trying to play cat and mouse with anyone...

You think the carrier bearing seems to be your first pick from the description I provided in previous posts?...

And again, I appreciate all the responses...

[DmaxMaverick]

Yes. That's the first suspect, and the easiest to diagnose. Replacement is fairly straight forward. Be sure to reinstall the U-joints at the same position as before removal. The carrier bearing/isolator isn't always the cause, but it is, by far, the most common failure.

Many of the earlier trucks with 2-piece shafts were updated (warranty recall) with a behemoth single shaft. Your truck isn't a candidate for the update (unless you go with a custom shaft). The 4x4 extended cab long bed and crew cab short beds were the longest chassis with the issue and covered update. Yours is longer, and wasn't included.

I wasn't gouging you about the lack of details and signature. Merely a suggestion. We all do it from time to time.

[f.forney]

Ok, all is well...

Will give it a try, hope it is the cure and since failure of this is common, I will look at it as preventative maintenance if it wasn't the problem...

Thanks

[f.forney]

Wasn't the drive shaft carrier bearing making the noise although the rubber spacer in the assembly was torn up pretty bad...

Guess I'll move on to something else...idk

[JohnC]

did you drain the oil and/or pull the cover? Any fuzzy stuff on the magnet? any chopped teeth or something like that?

I'm pretty sure you can pull the pinion and bearings out the front without disturbing anything. If you find the pinion bearings are the (only) problem, you could measure the distance from the end of the pinion to the gasket surface on the carrier and duplicate that dimension after changing the bearings. Should go together fine that way.

[f.forney]

Everything looked good when I had the cover off...

Will try, on the road more often than not, will post with more when something new is discovered...thanks

[DmaxMaverick]

I think further diagnostics and testing are in order. Once you've eliminated the U-joints and carrier bearing/isolator, unfortunately, what remains doesn't have an individual part more prone to failure than any other. They are all about equally less common. Don't condemn the pinion just yet.......

Verify the transfer case is disengaging the front shaft. If it's spinning when it shouldn't (even when the front diff is disengaged), it can cause drivetrain vibration.

Check the play of the transfer case output spline. The spline yoke should move no more than about 1/32" (side play) against the seal. If failed, this will usually lead to drivetrain howl/whine and seal leakage, but not necessarily at the same time or in a specific order.

Check rear wheel bearing installation/preload. The install procedure is very specific, and has been updated several times over the years. Too much or too little preload causes premature wheel bearing failure, and noise/vibration. Wheel bearing seal failure will usually follow shortly. Also check for string wound around the axle hub (happens often enough to mention).

Check the condition of cross-member transfer case and engine mounts. If they are cracked, hard, or too soft/spongy, they aren't doing their job.

Check the condition of the pinion harmonic balancer. The rubber isolator should be firm, intact and crack free. I've never seen one of these fail on late trucks, but I'm sure it can happen.

Check the alignment of the rear axle. Measure identical points on each side (outer axle housing tube), to a frame point forward. The tranny/transfer case support member bolt holes are symmetrical. If they distances differ, you may have a damaged spring hanger or worn bushing (they are rubber isolated as well). A differential as little as 1/8" can cause off-tracking noticeable by following observer.

Measure the relation of the axle to the frame. The axle tube ends should be the same, in relation to the frame. If different, it could indicate spring/hanger damage. This will usually cause axle misalignment, as well.

Measure loaded and unloaded spring arc and length (this requires U-bolt and/or shackle removal). Both should be the same when equally loaded/unloaded. If this is an issue, the will usually be a noticeable difference between a full and empty fuel tank.

[87max]

get the rear end up in the air and stable with very good wheel chocks & supports if you don't access to a lift. Run it, you should be able to hear it without getting underneath it. Obviously this is a two person deal. I believe the 11.5 is set up like a 10.5 so it's regardless. Disasemble by draining, pulling axle shafts out 3 or 4 inches, mark the side carrier caps like you would a main bearing cap for reassembly. Then mark the spanner nuts & count your turns! If I remember correctly you can leave the pinion in (age sorry I may be wrong). the entire ring gear & carrier comes out as one piece and is heavy, the bearings are on the sides of said carrier & are preloaded by said spanner nuts thats why counting the turns is so important.

[f.forney]

Will do! and be awhile till I get through this list ...

Thanks again for the info, will post any mentionable findings...

Busy time of d year so it'll be awhile