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DriveLine Vibe w/ ak57?

Discussion in 'The Garage' started by TXsizeK5, Nov 27, 2003.

  1. TXsizeK5

    TXsizeK5 1/2 ton status

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    How do I cure this? I have a CV shaft and my T-case is dropped. Shouldn't it be shimmed correctly? I haven't realy gotten a chance to look at it closely yet. but i'm getting vibes in up to about 35mph, high way speeds is fine, but when I decelerate w/out the clutch I get that ole' grinding sorta sound that I used to get with my non-cv shaft.
     
  2. bigblock44k5

    bigblock44k5 1/2 ton status

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    have you checked your ujoints? that would be the first thing. also make sure there is no play in the CV itself(the ball and cup inside).
    After all that is out of the way, it may be because of the lift you installed. to make a d/s not vibrate you need to equal the ujoint speeds to cancel eachother out.
    with a standard 2 ujoint d/s, you need equal angles at the transfer case and the rear so that when the front ujoint speeds up, the rear one is slowing down, this equals no vibrations.
    With a cv setup, the cv itself cancels out vibrations since you have 2 ujoints right next to eachother cancelling eachother out. this would mean that since there are 3 ujoints in a cv d/s, and 2 are already taken car of, the 3rd on is on its own. Which would mean that ideally the angle to the rear ujoint to axle should be straight at normal ride hieght for highway use. this would keep the bearings in this ujoint from speeding up and slowing down at all, hence no vibrations. hope this helps, i confused myself writing all this, anymore q's ask.
    Ken /forums/images/graemlins/thumb.gif
     
  3. TXsizeK5

    TXsizeK5 1/2 ton status

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    all angles should be correct becasue the lift itself came with shims. I don't know if anyone else had vibes after installing? but I might get a new CV shaft anyway.
     
  4. SF87K5

    SF87K5 1/2 ton status

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    Is your diff yoke inline with your t-case, or is your rear diff yoke level?
    Here is some help about Driveline Geometry
     
  5. marv_springer

    marv_springer 1/2 ton status

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    [ QUOTE ]
    How do I cure this? I have a CV shaft and my T-case is dropped. Shouldn't it be shimmed correctly? I haven't realy gotten a chance to look at it closely yet. but i'm getting vibes in up to about 35mph, high way speeds is fine, but when I decelerate w/out the clutch I get that ole' grinding sorta sound that I used to get with my non-cv shaft.

    [/ QUOTE ]

    Derek,

    Most of the time, you don't even need to add a CV shaft to cure a vibe problem. I didn't add a CV until I installed the Doubler.

    So.... you must have another issue.... Do you have a slip yoke output on your transfer case? Is the tailshaft bushing (bronze bushing inside tailshaft) worn? Is the driveshaft the right length? What's the pinion angle look like? can you snap a photo...?

    Marv
     
  6. TXsizeK5

    TXsizeK5 1/2 ton status

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    I looked at it a bit before i left and it looks like the slip yoke was pulled out of the tcase and inch or so...
    trucks not with me so I cant get a pic of the pinion angle it it was kind of in a bind though... my pinion used to point up but with the shims on the ak57 it is pointed more straight... this is best I can show [​IMG]
     
  7. kennyw

    kennyw N9PHW Premium Member

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    Your rear axle yoke should almost point at the Tcase even after the AK57 since you have a Double caridan driveshaft already. Try taking the shims out and measure the angle on your driveshaft. You want about 4 deg angle below pointing straight at your tcase to allow the pinion to rise upon accelleration.
     
  8. bigblock44k5

    bigblock44k5 1/2 ton status

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    TXsizeK5, you just answered your own question, if you read my earlier post you would see that the problem is your pinion angle being to low and not straight enough after installation of the ak-57. The AK is probably set up to use the stock non cv D/S.
     
  9. TXsizeK5

    TXsizeK5 1/2 ton status

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    [ QUOTE ]
    TXsizeK5, you just answered your own question, if you read my earlier post you would see that the problem is your pinion angle being to low and not straight enough after installation of the ak-57. The AK is probably set up to use the stock non cv D/S.

    [/ QUOTE ]

    What would the difference be if it WERE setup for a CV shaft? If my pinion angle is the way it is and i used a non-cv wouldnt it be worse? I thought I understood all that, but i guess i dont /forums/images/graemlins/confused.gif
     
  10. bigblock44k5

    bigblock44k5 1/2 ton status

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    Read my post. I stated that for a non-cv D/S to not have vibes, the pinion angle would have to be at or close to the angle of the transfer case. This way when the front ujoint is speeding up and slowing down, the rear ujoint is speeding up and slowing down at opposite times, cancelling vibes.

    With a cv shaft, the shaft to rear angle most be close to straight or the rear ujoint will vibrate since there is no ujoint to cancel it out.
    This site explains it all, hopefully it helps. good info that applies to your situation on the whole page, read it all.
    Driveshaft 101
     

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