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87 Chevy Rear Differential repair or replacement?!

Discussion in 'Chevy C/K Truck Forum' started by robertkni, Sep 2, 2013.

  1. robertkni

    robertkni New Member

    1987 Chevy P/U V10 model
    1/2 ton 5.7L V8 4wd
    As you can see from the pictures below, I need to do some major repair to the rear end on my truck. I'm a do it yourself guy and replaced the clutch in it last year which was pretty extensive for me. I am willing to do the job but just need some help in knowing WHAT to replace. The teeth on one of the gears are pretty much torn apart as pictured below. I know the gear ratio is 3.08 but not sure of the size. It is a 10 bolt differential if that helps. Everywhere i have read says 8 inch. How can i know for sure? So here is what i am asking,
    1. What parts do i need to replace?
    2. What size is my rear differential?
    3. Do i have to get the parts from the dealership or can i find them at a salvage yard? (Autozone said they can't get them)

    Thanks for your help

    IMG_5634.jpg IMG_5635.jpg IMG_5636.jpg IMG_5638.jpg IMG_5639.jpg

    Robert Knight
    87 chevy silverado 5.7L v8
  2. ChevyFan

    ChevyFan Administrator Staff Member 5+ Years 5000 Posts

    I'm going to move this as no one has responded.
  3. Jeff Dodson

    Jeff Dodson Member

    It's a lot more extensive that just replacing rear gears, there is back lash you have set, pinion bearing preload / crush, I am not experienced in rears either, I would love for someone to show me... But if you don't get them right they will howl and wear quickly. The backlash is very important.... However, I didnt think they used 3.08 gears in any 4x4 trucks....
  4. Pikey

    Pikey Moderator Staff Member 2 Years ROTM Winner 1000 Posts

    I have done rear ends before, under the guidance of someone who knew what they were doing. I still will not do it myself. I let someone that does only rear ends for a living do it. I don't know if there are rpo codes in the glove box of that year truck. The gears need to match the front or you will have a major issue when you put it in 4x4. You can order them online when you figure out what gears they are. My gear guy can get me gears cheaper than what I can find them online. So, if i needed them I would just purchase them from him.
    You are going to need a master rebuilt set (bearings, crush sleeve...) and a gear set. Your carrier may be ok, but, again, I am not a gear guy so you might want to have one look at it before you order parts.
  5. MrShorty

    MrShorty Epic Member Staff Member 5+ Years 1000 Posts

    I'm going to second what Pikey says -- A do it yourself guy can rebuild a rear end, but, I would encourage you to get a coach to help out the first few times you do it. Tolerances are just too tight and the costs of getting it wrong are to great.

    Or, get a complete axle from the junkyard. The trouble here might be finding a junkyard axle that 3.08 ratio (and you must match the front axle ratio). Unless -- you want to consider rebuilding/replacing the front diff with a different gear ratio.

    You can get parts from either the dealer or from the aftermarket -- it is up to you. GM parts will obviously cost more. Some aftermarket parts are also high quality (the shop who rebuilt my rear end likes Yukon Gear for aftermarket differential gears).

    One additional thought. You may not absolutely need to replace the carrier, but now is the time to consider whether you want to put a limited slip or locker in there.
  6. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    I've done many gear replacements, as Pikey and Dobson posted if I hadnt done a few before I wouldnt tackle this job without an experienced assistant looking over my shoulder.
    Step 1 for this job would be ensuring the correct ratio, 3.08 doesnt sound right for a 4wd, but if it is stranger things have happened.
    Step 2 would be ordering parts, ring and pinion, master rebuild kit, something I do as a habit every time I regear or rebuild is replace axle seals and bearings, and prefered lube.
    Step 3 would be more of an exploratory disassembly, make sure nothing else was damaged and inventory everything. Since you had catastrophic failure Id run a magnet into the axle tubes to collect any debris that may have gotten in there, then Id flush the tubes with parts cleaner or diesel fuel, I keep a common garden spreayer that can be pressurized so it has a good spray to wash stuff down, in this step your really just trying to washout any missed debris.
    next Id visually inspect the tube from end to center on both sides. If you see or think you have any debris or build up problems you can also swab the tubes with rags.
    Next step is assembly, make sure all torques are correct, make sure the pinion crush and backlash are set correctly. Backlash can be set in 2 methods, with a dial which is a moderately expensive tool that has 1 purpose or you can use blueing ink on the gears to determine a correct gear mesh pattern, either way has a lot of assembly/disassembly to get it right unless your lucky enough to get it the first time.
    Wrap up assembly with a good gear lube of you preference/specs then run the breakin period. Lube change at the specified period and you should be set.
  7. okysmokey911

    okysmokey911 Rockstar 100 Posts

    Im currently having to do this on my 93 k1500. The gear ratio should be stamped on the pinion gear or ring gear. You will see something like 41* 12 or 41* 11. Just divide 41 by whatever number is next to it and you will have your ratio. I had to do it that way because all of the rpo codes were worn off. I got a rear differential from the local U pull and pay. That was by far the cheapest and they offered a 7 month warranty on the whole setup. Think I payed 150 for the whole thing. Much easier than rebuilding it.
  8. Jake2670

    Jake2670 New Member

    yeah they did, i had a 85 4x4 with em n a 6.2L

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