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Rear Diff question

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Stoopalini, Dec 18, 2000.

  1. Stoopalini

    Stoopalini 1/2 ton status

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    Location:
    Austin, Texas
    This past weekend, I noticed a problem with my truck and am hoping you guys can help me figure it out.

    The 1st sign of the problem is a vibration when accelerating between 35 and 45 Mph. Once I get above 45 Mph, the truck 'humms', but the vibration seems to settle down.

    The best I can describe it is to say the truck is 'resonating' when above 45 Mph and accelerating. When I let off the gas, it doesn't resonate anymore, but I can still feel a vibration.

    I jacked up the rear of the truck and placed it on jack stands to try and figure this out. The U-Joints look fine and the only problem I found is play in the rear end.
    The rear wheels will spin about 1/2" before catching and there is play in both wheels when pushing on the tire.
    I can push the tire in and pull it out about 1/2" and was wondering if this is a lot of play? Are my wheel bearings shot?

    any help is greatly appreciated. Maybe I should just yank out the 10 bolt, and throw in a 12/14 bolt instead, hmmmmm ...........

    Any other tests you guys can offer to try and diagnose this problem?

    Thanks,

    Thomas.

    -- '84 K5 Blazer --
    http://Stoopalini.coloradok5.com
     
  2. Blazer1970

    Blazer1970 1/2 ton status

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    There shouldn't be anywhere near 1/2" end play in the axles. I would pop the cover off and check it out. Possibly a broken spider gear cross pin?

    Tim

    70 Blazer CST 4X4 350 SM465 NP205
    87 Burb 4X4 350
    01 GMC 2500HD 4X4 Duramax/Allison
     
  3. Heath-La. 89GMC

    Heath-La. 89GMC 1/2 ton status

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    Check your yoke. It could be worn or just need a little adjustment. I had a similar problem and couldnt figure it out.. I changed ujoints and still had it.. then I dropped the driveshaft at about 60. Found out what my problem was.. went to the junkyard and had back goin the next day.
     
  4. Stoopalini

    Stoopalini 1/2 ton status

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    Thanks guys, I think I will take the Diff Cover off this evening when I get home and check it out.

    I know nothing about the workings of a rear end, so maybe you could help me out here:

    What and where is the yoke? I have swapped rear ends many times before, but never actually opened one up and worked on the inside guts.

    Is there anything specific I should be looking for once I get it open? Anyone have pics online I could reference?

    Someone told me that maybe I just need to shim the rear end, but that doesn't mean anything to me either.

    Thanks again guys; hopefully I get this resolved soon. I really wanna go wheeling next week!

    Thomas.

    -- '84 K5 Blazer --
    http://Stoopalini.coloradok5.com
     
  5. Heath-La. 89GMC

    Heath-La. 89GMC 1/2 ton status

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    The yoke is the thing with ears that sticks out of your rear end and the driveshaft attatches to. It might not be the problem.. but it is a suggestion. There is a bolt that holds it on to the pinion gear. If you do try to tighten it.. make sure you dont get it real tight. it needs a little play in it. But its possible that it might be too loose. Check the ears real good and make sure there are no bad worn spots that would cause the ujoints to not fit snug. oh well.. good luck
     

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