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87 Jimmy (full size) rear drive train noise

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Goodolboy, Mar 13, 2003.

  1. Goodolboy

    Goodolboy Registered Member

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    I recently traded a 10" lift from a friends suburban to my jimmy (full size.) He wanted to go back to stock while I wanted the height. When the lift was on, I connected the rear driveshaft and drove it 'bout two miles to a shop to have the exhaust pipe moved around to accomodate the front shaft.
    After getting the truck off the ground I realized that both shafts needed to be lenghtened, which I did. After they were reinstalled, the back started to make a horrific sound. When I let off the gas (especially from higher speeds, 30+) a rachetity / metallic rattling sound began to echo through the truck.
    After taking getting the wheels off the ground, I determined the noise to be coming from the rear diff or axles. I changed all the fluids (didn't help). Everything looks fine, but I need some ideas. I don't see how a bearing could have gone out over night, literally. My only idea on this matter is that the too short driveshaft I used at first tweat something, but what?

    Any thoughts or ideas would be helpful. This "free lift" is starting to cost me an arm and a leg. <font color="red"> </font>
     
  2. Dale fan

    Dale fan 1/2 ton status

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    I am no expert on this by no means but it sounds like your pinion angles are way out. With that much lift you will have to lenghten the shafts and use shims or something to adjust your driveshaft/pinion angles. You might also have to lower your tcase. Your buddy's /forums/images/graemlins/burb.gif is longer than your /forums/images/graemlins/k5.gif and that makes the angles not as bad on his.
     
  3. spray004

    spray004 Registered Member

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    Yeah definitely sounds like the pinion angle. A bad pinion angle is HARD on U-joints. Thank god for life time warranties at car part stores. The best way to solve this is to get a new drive shaft with CV joints or have your spring perches rewelded so that the angle is correct.
     
  4. 84_Chevy_K10

    84_Chevy_K10 Banned

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    It actually sounds as if the yokes of your driveshaft may be hitting each other.

    You're not getting any terrible vibration? Just noise? Sounds to me that some clearance grinding on the shaft may be all that's necessary.

    If the complaint was vibration, I'd say you have angle problems. However...if the yokes really are binding, I'd get that taken care of immediately as it will destroy u-joints quite quickly and you'll find yourself stranded.
     
  5. MudNurI

    MudNurI 1/2 ton status

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    I did a search for my old post on this- I had the EXACT same problem- 100% the same.......I knew it wasn't my u-joints or my angles or anything else like that- I found my problem- and this is what it was...

    [ QUOTE ]
    replace the pinion seal and torque the pinion nut back down you should be fine...

    [/ QUOTE ]

    My pinion nut was so loose, that I took it off with my hand- 3 turns and it was on the ground. Here's part of a reply that I received regarding my problem

    when we swapped my axles- this must have been something that we over looked- I know we did not replace the gasket- which we should have.....
    [ QUOTE ]
    The pinion seal should definitely be replaced (under $10), and check the yoke for a groove (where the seal used to ride). If it will catch your fingernail, it should either be replaced or "Speedy Sleeved" (you can get those at NAPA). Depending on how long it went the pinion bearing and/or the crush sleeve could have been damaged too, but replace the seal (and yoke if needed) and try it. If there is no noise, then don't worry about it, if there is you MIGHT have to "did a little deeper".

    [/ QUOTE ]
    check the pinion nut-

    Brandy
     

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