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Rear Driveline angle?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Mike87, Oct 6, 2000.

  1. Mike87

    Mike87 Registered Member

    Feb 18, 2000
    Likes Received:
    San Jose, CA, USA
    What is the rear driveline angle supposed to be? I have stock height suspension with the exception of 1" blocks in the rear for leveling purposes. (Truck is used primarily for towing) There is a rhythmic vibration that I feel at about 70MPH. I have been told that it is driveline related, but have had both driveshafts replaced (with new). There is a slight difference between the rear driveshaft angle and the differential input, meaning they are not in-line. Could this be my problem? If so, how do I correct it?

    Mike (#87)
  2. Blue85

    Blue85 Troll Premium Member

    Jul 26, 2000
    Likes Received:
    Grand Rapids area
    With a 1" lift block, you are definately not operating the U-joints at too great of an angle.

    Regardless, the concern is not with the angle of the driveshaft, but with the angles that both of the U-joints are operating at. To minimize vibration, the angles of the front and rear joints should be within about 1 (maybe 2) degrees of each other. The simple way to make this happen is for the pinion in the axle to be exactly parallel with the output shaft of the T-case. First, you have to determine what the angles are. Then, you have two choices to correct the angles, if they are wrong.
    - Shim the rear axle with commercially available shim wedges that go between the leaf spring and axle spring pad
    - lower the transfer case. This is actually really easy on K-5's

    I hope that this helps.

    '85 JIMMY
    '90 paint/grill/trim 5"susp 33/12.5/16.5
    Fresh 350 B&M '87 TH700
  3. djohnsn

    djohnsn 1/2 ton status

    Feb 17, 2000
    Likes Received:
    Plano, Texas
    Can someone give me a good method for accurately measuring the pinion and output shaft angles?

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