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Pinion angles

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by wrathORC, Jul 18, 2003.

  1. wrathORC

    wrathORC 1/2 ton status

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    OK, I believe I have a pinion angle problem. I read through the archives and it seems that most people prefer the pinion pointed up. I need your guys' expertise before I spend money. I think I need to go buy 4-5° shims to point the pinion back down, U-bolts, center pins, and new universals.

    I'm no rocket scientist but it doesn't make sense that a pair of universals can survive this kind of abuse. If they can then I won't shim it and I'll just replace the universals since I know the front one is the original (still has nylon injected in it) and there is no signs of the rear one being replaced in recent history in its 84,000 mile life. Money is kind of tight right now after going over budget so if I can save the $40 for U-bolts, $40 for shims, and $10 for pins then I would rather do that.

    The vehicle: longbox truck with a ten bolt and 52" springs that has a shackle flip (4" homegrown variety).

    Symptoms: I developed a clicking noise similar to small pieces of metal getting shot at aluminum flashing today. I've never heard this noise before and all universals I've had go bad just clunked. I read here that this noise can be attributed to universals. The only other noise it could be is the rear differential. There is some slop in the rear universal (less than 1/16th of an inch) and an unmeasurable amount on the slipyoke one. The pinion seal started leaking and the pinion bearings were a little noisey but tight prior to assembly.

    Potential problem: The pinion points up more than the angle of the driveshaft. This seems to me would eat universals alive since common sense says they should be angled such that they cancel each other out. However, my neighbor's Jeep has a larger pinion angle and the guy down the street is running a completely insane pinion angle without failure.

    Here is a picture. The camera is level and the front of the truck is pointed downhill.
    [​IMG]

    Here is another picture in which you can see the angle made by the leaves, perches, and back of carrier in relation to the frame.
    http://www.wrath.com/projects/vehicles/images/84k10/liftandaxles/littlerock_reardiscs.JPG
     
  2. Polaris

    Polaris 1/2 ton status

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    I'm having a pinion angle issue myself. Mine are 6° differing from the pinion yoke and the transfer case slip yoke. I have shims in that came with my Rough Country spring pack, but will be removing them tomorrow. See if the following link will help you:
    http://www.4x4wire.com/tech/pinionangle/
     
  3. wrathORC

    wrathORC 1/2 ton status

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    Thanks

    After reading that it was just as I expected, the line through the pinion shaft and the line through the crankshaft are supposed to be in parallel. Too bad I'm too poor to afford a CV shaft, eh?
     
  4. Mastiff

    Mastiff 1/2 ton status Premium Member

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    Everything I've read would lead me to agree with you. The pinion should, theoretically, be at the same angle as the T-case output. I think in reality it'll never be perfect, but judging from your picture, it's pretty far off. I think shimming it to bring the pinion back down is a good idea.
     
  5. u2slow

    u2slow 1/2 ton status

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    I can't see your t-case, but my vote is for shimming the pinion down as well. My buddy's truck looks about the same. All his u-joint angle is at the other end of the shaft, and he's got really soft springs. When he applies throttle the pinion rolls even further up. 1st gear romps always blows the u-joint. /forums/images/graemlins/rolleyes.gif Usually takes either the shaft yoke or pinion yoke out with it too.

    Good article here. Billavista cranks out another one.
    http://www.pirate4x4.com/tech/billavista/PR-shaft/index1.html
     

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