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can ujoint vibrate without looking bad?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by bigk, Oct 28, 2001.

  1. bigk

    bigk 1/2 ton status

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    I get a bad vibration under acceleration, goes away when I let off, but the rear u joint looks OK. No lift in the rear, just an add a leaf in the front. 33 inch Wild Country mud radials, 76 3/4 ton axles under my 87. Its stock otherwise.

    Karl
    Temporarily Unemployed Underwear Model
    87 3/4 ton
     
  2. I have had a u-joint go bad, but every time I looked at it I thought it was fine. It was because the damn thing had tension on it and you couldn't see how bad it was. Block your tires and put it in neutral so you can move the driveshaft whiole watching it. I hope this helps.


    [​IMG]<font color=red>BigBurb[​IMG]
    <font color=purple>I Like my Burb'n on the ROCKS !!
    <font color=black>Imported to Kentucky through military channels !!
     
  3. CaptCrunch

    CaptCrunch 1/2 ton status

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    Also a lot of times you need to take out the driveshaft to really tell if a jt is bad. Like was said... most times with tension on it it looks fine.

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
     
  4. wayne

    wayne 3/4 ton status

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    I had a bad u-joint that looked fine with pressure on it. I took the shaft out and found out it had alot of slop in it.

    See <a target="_blank" href=http://coloradok5.com/gallery/Waynes-Toy>Project Mighty Mouse</a> here.
    <font color=blue>Wayne<font color=blue>
    <font color=blue>Happy Trails<font color=blue>
     
  5. bigk

    bigk 1/2 ton status

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    I'll try doing that this afternoon.

    Karl
    Temporarily Unemployed Underwear Model
    87 3/4 ton
     
  6. bigk

    bigk 1/2 ton status

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    Well, I replaced the ujoint this afternoon. The old one was only getting grease on two ends, the other two were dry. Took it out for a drive and it still vibrates under acceleration. Could it be in the tranny or transfer case? Or maybe a motor mount?

    Karl
    Temporarily Unemployed Underwear Model
    87 3/4 ton
     
  7. shawnboy

    shawnboy 1/2 ton status

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    The tranny mount could be bad as well as the front u joint on your rear shaft. Have you had your driveshaft balanced? Also check your pinion yoke for play, could have backed off or your pinion bearing is nfg.
    Shawnboy.

    If you are having too much fun it's probably illegal.
     
  8. backlash

    backlash 1/2 ton status

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    Can a bad motor mount cause vibration in the rear?
     
  9. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Vibration under acceleration would indicate that the pinion angle is a little off, or your tranny/t-case/motor mount(s) could be bad. The pinion rotates up on acceleration, and the angle can be compounded when mounts start to sag. If your u-joints haven't been touched in over two years, I would replace (all) of them regardless. I would also look very close at the motor and tranny/t-case mounts for excessive "squishing". Get the poly replacement mounts and then you never (or at least for a very long time) have to worry about them. JMHO.

    See my rig at <a target="_blank" href=http://coloradok5.com/gallery/Leadfoot>http://coloradok5.com/gallery/Leadfoot</a>
     
  10. Pugsley

    Pugsley 1/2 ton status

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    I had one that looked fine, and felt fine turn into this: pugsley.alloffroad.com
     

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