2001 Rear Axle Replacement - 240K
 

I was in the process of replacing my rear wheel bearings since there was a fair bit of play at the hub on the passenger side. It turns out the axle is very worn and thus a new bearing will not resolve this issue. The pinion seal has been leaking for 2 years and there is (up and down) play at the yoke. There has been a noise in the rear end when accelerating for some time. I returned from getting the bearings/seals and started the project. I noticed the rear differential casing was very hot - especially up front by the pinion.

1) Is this a symptom of a bad pinion bearing?

There is no "G" code listed on the Service Parts Notification in the glove box. However, with the diff cover off I see the following stamped on the pinion gear 12-41-GM which I'm guessing is the 12/41 gear ratio of the rear end and thus it must be the GU6 3.42 ratio.

2) Would this be a correct assumption?

A search on a local salvage yard web site has a 1998 rear axle assembly available for $300. I believe this is probably my most economical option.

3) Do you agree?

4) How do I tell if it's limited slip or not?

1) Yup, and quite possibly the pinion shaft too.

2) 12/41 indicates 12 teeth on the pinion shaft, 41 teeth on the ring gear... (41 divided by 12) is in fact a 3.42:1 ratio.

3) When it's all said and done, most definitely. The cost of a ring & pinion set, axle shaft, bearings, fluid, gasket, axle seals and whatever else you find once you're in there, $300 is cheap, go for it.

4) Post an image of the RPO codes, (white sticker in the glove box).

Job complete. Rear end minus calipers and rotors cost me $275. The '01 rides smoother and quieter than it has in years. Not the slightest bit of vibration. The pinion bearing must have been worn for a long time.

Quick tip for someone else doing this job. On my old axle, I cut off the two welded tangs that hold the break lines to the axle. Then on the replacement, I cut 1/4" slots on the top of the tangs and removed the break lines through the slot. By leaving most of the circular part of the mounting hole in place, I was able to slide my break lines in through the slot and use the existing clips to hold it in place. This allowed me to do the swap without having to break any brake line connections.

I am very interested in this post... I have been chasing a vibration in my '97 since I bought it 3 years ago... its nice under 50mph, but over that I have a loud vibration sound coming from the rear... originally I thought it was coming from the front, I replaced the front wheel bearings, axle shafts, no change, new tires, no change, u-joints (were bad) no real change.. so I am thinking rear wheel bearings..

What kind of noise were you experiencing? were you getting any vibrations?

Other than this issue, the Blazer is great and low mileage (just under 100K)

Thanks in advance..

The noise was a "whirrring" sound that would show up while accelerating or under load such as going up hill and yes there was a vibration that you could feel - especially on your feet. It would be most evident over 45 mph. You can check your pinion bearing by grabbing the yoke on the front of your differential and seeing if you can move it up and down. Mine had about 1/16" of play - there should be none.

I believe that a couple of years ago when I drove mine with a bad u-joint, that this may have caused my pinion bearing (and seal) to wear from the up and down movement. Check to see if you have gear oil residue around the front of your differential indicating that the seal has worn - which would probably be because your pinion bearing is worn and there has been constant up and down stress on the seal.

After replacing the rear axle assembly, I still had a slight vibration that continually increased with speed (unlike a balance issue which typically can go away at certain speeds). I did however, take it in yesterday and had the rear wheels re-balanced - start with the easy things. One of them was off by 1-1/2 ounces. This helped reduce the vibration but not totally. Ask them to check them rather than just re-balance them as most shops will just stick them on the wheel balancer, rip off the weights and balance them.

I have always know there were a couple of small dents in the rear of my drive shaft. Yesterday I replaced the drive shaft with one from a salvage yard ($45) and now there is virtually no vibration.

It's easy to check your rear wheel bearings by simply jacking up the vehicle and grabbing the wheel and seeing if there is up and down (or side to side) play. If there is, don't go out and by wheel bearings and seals until you remove your axles and inspect them. Chances are if the wheel bearing are worn, so is your axle. The wheel bearing do not have an inner race - they use the axle for this. Mine were terribly worn. New axle kits were $200. The fact that my pinion bearing was worn as well made me look at the savage route. If you choose to do the same, make sure you check the pinion and axles before you buy by grabbing them and checking for play.

Hope this helps.

Thanks for the reply, I will check this for sure... I also have to check my temp sending unit as the guage is swinging all over the place...

good thing its a winter vehicle and not an every day driver.

Just had to deal with a wheel bearing failure on my '99 S-10 Blazer. 208,000 miles and the right rear started smoking and almost lost braking, with the dash light coming on.
Found parts of the rear bearing hanging out and required replacement of the axle as it badly grooved. What I learned in doing this is that should you search for a disc brake axle but can only find a drum brake axle, you can use it but it will require grinding the inside of the caliper bracket to alow for the extra thickness on the drum brake flange.

Service rearend LOL I`m not touching that one

Because of it's age and miles the truck has seen plenty of service and has been the absolute most expensive vehicle I've ever owned. I ride bikes year round as my primary trans so I only put 3-5,000 miles per year tops on this. It's there when I can't safely navigate the roads, deer camp and launching the boat. I'm hoping I can keep it alive for several more years. My post was to advise others that in a pinch a drum brake rear axle can be used on a disc brake vehile if the above modification is made. I needed to get home, about an hours drive under good conditions, it was 20 degree weather, we were in my buddies snow laden driveway and 12 inches of snow were forcast for that night. The drum brake axle was my most feasible option. Happy New Year.