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noise coming from rear end

Discussion in 'GM Powertrain' started by 96Z71VORTEC, Dec 2, 2008.

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  1. 96Z71VORTEC

    96Z71VORTEC New Member

    What happened
    I was driving around today about 35-40 mph and all of a sudden I kept hearing this grinding/clunking noise coming from the rear end. I was almost home so I drove it slower to 20-25 mph because it sounded like my driveshaft getting ready to explode (I've had that happen before on an 85 Toyota at the carrier bearing). Anyway, I pull in to the driveway, chocked the front wheels, put it in neutral and jacked up the rear end, had a buddy spin the rear wheels while I was underneath, and the noise was coming from the rear of the driveshaft at the differential.

    What I've done so far to this point
    I checked the fluid level in the differential and it was BONE DRY. I took another vehicle to get some 90W gear oil, filled it level with the drain plug and buttoned it back up. Dropped it back down, went around the block about 30-35 mph and it was fine. Took it to the highway and drove 60-70 mph and it was fine. My thoughts at this point are "No more nasty sound coming from my truck! Easy fix, yay!".

    The turning point/climax/evil:grrrrrr:
    I got back on the same original road heading towards my house that all the noise started on, same original speed before the gear oil refill, just before the road I turn on to my house....as soon as I cut the corner, I heard it again!!! I went around the block a couple more times turning each time to make sure I heard what I heard, and even when going straight, and it DEFINITELY still makes the grinding noise.

    What I can tell/my thoughts
    The U-joints look fine although I will replace them anyways once I have everything apart anyway (what can it hurt?). HOWEVER, there is A LOT of play in the PINION BEARING (I can take the rear end of the driveshaft and shake it around!) and there is a slight amount of gear oil leaking out onto the yoke so I think that I am going to have to replace the pinion bearing and pinion seal. If that is the case, I know that won't be an easy 30 minute fix, but more like 5 to 6 hours, maybe even a couple of days with the weather being like it is.

    How do I fix it?
    I'm pretty sure for me to change out this bearing and seal, I am going to have to pull the wheels off, rear drums off, pull the axles out, take the differential cover off, drain it out, gut the whole thing just to get to the pinion bearing. I would inspect each and every thing during the removal process and note any problems on anything and post it on here. What part numbers and exact specifications should I be looking for? I would be looking for an inner pinion bearing, would it be for an 8.5" R.G., would there be any specific lengths/diameters/radiusus on the bearing? Also what special tools would I need (other than the ordinary wrenches/ratchets/sockets/screwdrivers/hammers)? Is there a special way to put the bearing in if that is the case? Has anyone ever done this before and could provide a detailed explanation on how to do it?

    What I would get if nobody had specifics:

    http://www.rockauto.com

    -Chevrolet
    -1996
    -K1500 Pickup
    -5.7L 350cid V8
    -Drivetrain
    -Differential Pinion Bearing

    ***then these would be the ones I would toggle with because I don't know which exact one to get*** I'm assuming it is the inner pinion bearing and not the outer

    I believe this part fits either application

    Timken Part # M802011
    Cup; Front Axle, Inner 4WD; 8.25" R.G.
    Cup; Rear Axle, Inner; 8.5' R.G.; 1st Design $4.84


    BCA/NATIONAL Part # M802011 {Taper Bearing Cup Outer Diameter=3.25" Length=0.795" Radius=0.125"}
    Taper Bearing Cup; Front Axle; Inner; AAM IFS-8.25" R.G.
    Taper Bearing Cup; Rear Axle; Inner; AAM 8.5" R.G.[​IMG]
    $7.01$0.00$7.01

    Cup/Cone/Taper....I have no idea

    TIMKEN Part # M802048
    Cone; Rear Axle,Inner; 8.5" R.G.;1st Design
    Cone; Front Axle,Inner,4WD; 8.25" R.G.$9.88$0.00$9.88
    BCA/NATIONAL Part # M802048 {Taper Bearing Cone Bore=1.625" Length=1.01" Radius=0.14"}
    Taper Bearing Cone; Front Axle; Inner; AAM IFS-8.25" R.G.
    Taper Bearing Cone; Rear Axle; Inner; AAM 8.5" R.G.[​IMG]
    $14.32$0.00$14.32

    -Differential Pinion Seal

    Timken Part # 2043
    Rear Axle; 8.5" R.G.; 1st Design $4.17

    I don't consider myself to be a mechanic by any means, but I have pretty good common sense, so I guess that counts for something. I would prefer to learn how to do this myself vice taking it to a shop.

    Anybody have any thoughts/advice/ideas?

    I appreciate any and all replies. Thanks
    Last edited: Dec 3, 2008
  2. Crawdaddy

    Crawdaddy Moderator Staff Member Platinum Contributor 1000 Posts 100 Posts

    Have you ever rebuilt and set up a diffential before? If not, best to strip it down, repair the issue, and then bring it to a pro to be set back up. The clearances and such in differentials are very picky, and you need some oddball tools to get the job done like an inch-pounds torque wrench. Tim or Mike can tell you more.
  3. retired

    retired New Member 100 Posts

    As lonn as you put it back the same way you took it apart you will be fine. A repair manuel will be helpfull.
  4. k.daddy1

    k.daddy1 New Member 100 Posts

    It's not a hard job to do. You'll have to drop the drive shaft and if you have an impact gun remove the nut from the yoke. Remove the diff cover/spider gears and the input pinion will come out the back with what is left of the bearing. Get new bearings, crush spacer and yoke nut. You'll need a ft lb torque wrench for the yoke nut. If you have a book, just follow the steps in there, pretty simple job and cheaper than a dealer. Get your hand dirty and good luck!
  5. 96Z71VORTEC

    96Z71VORTEC New Member

    I have never rebuilt or set up a differential before. Even if I did take everything apart and replace all the worn parts, what would be the point in taking it to somebody else at that point? I might as well let them do it start to finish. What special tools would I need to set the clearances and such, and what would they be for each part that needed clearance and such?

    If I take it apart and put it back together the same way I took it apart, I would think that there would be more things involved than just do that. And if it is as easy as you make it sound, I'm sure something would mess up.

    I'm sure it is not hard to do given I had detailed instructions and the right tools. I found a kit from rockauto, below is the picture and details of what it is. If I have what book, a Haynes? I have one (24065), but I'm not seeing where it would provide the steps/process/detailed instructions you are referring to for this exact fix. I know how to drop the drive shaft, I have an idea how to get the drums off but it is in the book, the axles I know are in the book, the gears that's a trial and error and I think some of it is in the book, and the rest should be easy. My thing is the clearances and such and the special tools I will need to do this. An impact gun to me would not be special, but I do have one.


    BCA/NATIONAL Part # RA321 [​IMG] {Bearing/Oil Seal Kit}
    Rear Axle; AAM 8.5" R.G.[​IMG]
    $69.99


    I do want to and need to get my hands dirty but I need direction first to get to that point!

    Thanks for the responses so far and hopefully more to come
  6. k.daddy1

    k.daddy1 New Member 100 Posts

    Haynes books aren't very good. If you can get a Chiltons, it will have the process in there. If you have a dlearship that is worth 2 cents in your area, they can provide a printed step by step process of how to do it. Once the yoke on the diff is off, the diff cover is off, you'll see a small 8mm (i believe) bolt that retains the 2 spider gears in the carrier. Take that bolt out and push the spider shaft out of the carrier with your finger or soft punch, watch because the spider gears will fall out at this point. jake up the rear end and rotate the carrier around so the pinion gear can some out. Tap the front of the pinion shaft with a dead blow hammer and walla, the input shaft is out with the bearings. Just make sure after you put the first bearing on the pinion, that you don't forget the crush spacer as this sets your backlash. Put it back together in reverse order. The backlash is .009-.013 (i believe) would have to double check, but it should be right on once you have the yoke installed and torqued.
  7. 96Z71VORTEC

    96Z71VORTEC New Member

    I found out the problem! It's such an easy and cheap fix! I am right in the middle of fixing the issue(s)! I will post pictures and a full description later on tonight!
  8. 96Z71VORTEC

    96Z71VORTEC New Member

    Or so I thought...I pulled the differential cover off, drained all the oil out of it, and the first thing that I seen was a BOLT resting at the bottom of the differential. It was one of the ring gear bolts and it was all chopped up and chunks taken off of it. That was the really loud noise I kept hearing in the rear end when I was driving around with no gear oil. And after adding the gear oil, it had quietened down only because it would take it a while to move through the oil while ricocheting off of the ring gear and what not. Plus, the rest of the ring gear bolts were 1/4 of the way up to 1/2 of the way BACKED out of the threads of the ring gear. Somebody had this apart before and didn''t torque them down to specs (reason why I have the other post about the torque specs and process) and/or add threadlocker (medium strength). Or it hasn''t been messed with and it''s just 12 years of vibrations and driving that made them back out. Well now, I''ve reached the point to where I''ve driven it down the road (not even a quarter mile) to the local auto shop and they said $1200 to redo the whole rearend. The yoke still has play in it and I have replaced the chopped up ring gear bolt from a dealer. Would I need the bearing and seal rebuild kit, or do I really need new axles, posi, etc.? Is it really that necessary? All I should have to replace I think is the pinion bearing, the crush sleeve (that one seems complicated after talking to a 4x4 shop today), and the pinion seal. I really, really need help with this and I appreciate everyone that has taken the time to read this crazy post, and just might be willing and able to help me out. I really can''t afford taking it to a shop.

    *** I cleaned out the differential after I torqued down the ring gear bolts to 90 ft. lb., put the cover back on, and I am currently in the process of adding the gear oil/posi additive. I am going to do that, put the plug back in, and drive it around and see what happens. If it still does it I have no choice but to take it to a shop, for $1200 with a one year guarantee and get it all done. I'll add more tonight or tomorrow with what I find out. Thanks again to those who have replied
  9. 96Z71VORTEC

    96Z71VORTEC New Member

    So of course the clunking noise is gone since I put a ring gear bolt in and tightened them all down. However, there is still the play in the yoke and pinion bearing/shaft. I believe the pinion bearing to be bad and that's it, however seeing as to do this myself, I'm going to have everything apart anyways so I might as well get new bearings for the carrier, pinion, and axles. It's a kit and it is $70 from rockauto. I talked to a guy on the phone at a nearby 4x4 shop and he said that if I replaced just the bearings and seals, and the crush sleeve, and some kind of shims (I don't know what he was talking about there) that should be all the parts I need to fix it. The tools I don't have but maybe could borrow from somewhere. And at this point I'd have parts and tools and all I would need is directions. I know it's not as simple as putting it back together the same way I took it apart. Has anybody ever done this before and could walk me through it step by step? Somebody said in an earlier post the steps are in the Chiltons books. I went out and bought one and it is not in there. Maybe an older Chiltons, one of the thicker books before some genius decided to not include everything on a complete tear down and rebuild. It doesn't sound complete to me. Please, I am begging anyone and everyone. Please, I need help with this.
  10. CoolAirVw

    CoolAirVw New Member

    Can you just tighten your pinion nut as a temporary fix?

    Pinion has a front and rear bearing. Possibly with movement in the pinion there could be wear on the ring & pinion gears.

    The carrier has bearings also. You can inspect them but if there is pitting on the race with the caged bearings it can be impossible to see. The outer race will usually show some distress if this is the case but not always.

    On either side of the carrier bearings there are shims. Look like very big fat washers. Left and right side are different sizes and need to be put back in same spot as they came apart. I like to hang them on thier respective leaf spring U-bolts to keep them on the correct side.

    Also the bearing caps inside the diff need to be put back on in their respective spots.

    Oh, be sure to inspect the axles for pitting in the bearing area as well.

    Be careful when removing the bolt that retains the shaft that the spiders spin on. Tap on it a little, then before loosening it, tighten it ever so slightly. Also use a 6 point socket or wrench, so that you have less chance of rounding it. These things used to break alot on me before I started taking preventive measures. Sometimes it can be a real nightmare when that bolt breaks, because it leaves the pin in there retaining the shaft that the spiders spin on, making it impossible to take the rear end apart.

    Clean differential out. Failed bearings make metal flakes that ruin other bearings, or your new bearings. Take a rag soaked in solvent and use a broom handle to shove the rag through to clean out the axle tubes.

    There is a crush sleeve between the front and rear bearing that "crushes" to set the preload on the pinion bearings. You must replace the crush sleeve.

    The method that you described to change the bearings is good. You can remove the pinion bearing races from the differential housing with a long punch and hammer, but it always "pushes" up some of the metal that the races bottom out on, so inorder to avoid the races sitting too high on this "raised" portions, take a flat punch and knock those burrs back down. It wont hurt if they are slightly low, because the undamaged portions will support and locate the race just fine.

    Installing the race's usually requires a nice fitting driver. But a DIY'er could take the original races to a grinder and make the outside diameter smaller (alot of work!) then use them to drive in the new races. You need to reduce the diameter so that you can get them out after driving in the new ones.

    Removing the rear bearing off the pinion usually takes a special puller, or a bearing splitter and a press. I've seen guys who are real good with a torch cut the bearing off. Also if you have a cut-off wheel, you can cut off the cage, letting the rollers fall away, then cut the inner race diagonally. Cut it carefully, leaving just a tad bit of metal, then use a sharp chisel in the channel you cut, and if you hit it hard enough, and you've cut it deep enough, then the remaining metal will crack, releasing the press fit, allowing you to either slide it off or tap it off easily with a hammer & screwdriver. I like using this last tecnique best, even though I have pullers and press, because I can cut it and chisel it faster than I can set up the puller or press.

    Note that under the rear bearing on the pinion there is a shim. Be careful not to destroy it or loose it. It will need to be placed under the new bearing. If it gets slightly "boogered" it can be hammered lightly to flatten it back out.

    On reassembly you must use a new crush sleeve. Crushing the sleeve requires something to hold the yoke from spinning and a breaker bar with big cheater pipe. A real good impact usually works, but not everytime.

    Crush the sleeve till there is zero movement in the pinion, then use a inch pound torque wrench to measure turning torque, increasing the "crush" till the turning torque is correct. You'll need to find the spec for your truck. This makes sure there is the correct "pre-load" on the bearings. If this step is done improperly it is likely your bearings will fail or your pinion nut will come loose.

    Sometimes, but rarely, after replacing bearings the gears will whine due to slightly different dimensions on the new bearings, which locate the gears slightly differently. In these cases the Ring & Pinion would need to be reshimmed to quiet the whine. This takes a certain amount of expertise, but usually its not an issue. It is an issue alot more when replacing the ring & pinion.
    Last edited: Dec 11, 2008

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