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Driveshatf/ U-joint

Discussion in 'The Garage' started by BrownK5, Jan 8, 2006.

  1. BrownK5

    BrownK5 Registered Member

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    I lifted my 79 k5 6" and less then a week later the front u-joint on the rear driveline broke. I replaced both joints on the rear shaft and the next day it made kinf of like creeking noises coming from the driveshaft, they sound similar to the noises that it made right before it broke the 1st time. ive noticed it vibrates when im on the gas. what have people done? im afraid that its about to break again and dont realy want to deal with it again. thanks for any help.
     
  2. Muddytazz

    Muddytazz 1 ton status

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    How did you lift the rear? Did you shim your rear axle in any way to compensate for the driveline being at an odd angle?
     
  3. muddybuddy

    muddybuddy 3/4 ton status

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    what t-case do you have?

    its from the angles on the u-joints. depending on what t-case you got, ive got a cv driveshaft so ud never have to worry bout binding again.
     
  4. midnitewarya

    midnitewarya Sounds like a problem for future me. Premium Member

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    It really is all about the angles. Did you lower the t-case whe you did the lift? What are you angles like? If you have a standard driveshat (one u-joint at each end) the t-case and the axle pinion have to be parallel. This is because all u-joints naturally vibrate. In a standard driveshaft, the t-case and pinion being parallel allow the two u-joints to cancel each others vibration. The more out of allignment the pinion is from the t-case, the more vibration you will have.

    If you have a c/v driveshaft (two u-joints at one end, one on the other), the pinion has to point (I think you have like 1 degree of play) at the t-case output. This is to ensure that there is no angle in the pinion u-joint, so that a straight line is formed from the second u-joint of the c/v to the u-loint of the pinion. The two u-joints in the c/v cancel each others vibrations, and there is no vibration form the 3rd u-joint.

    Also, on a standard driveshaft, the more lift you have (more space in height between the t-case and the pinion) the more vibration you are going to have. I think the standard for diveshaft angle is 32 degrees. Any more than that, you risk serious failure.

    So, just check all your angles, and I hope you find the problem.

    Al
     
  5. BrownK5

    BrownK5 Registered Member

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    i lifted the back w/ add-a-leafs, and angled 4" blocks. im not sure what t-case i have but will find out today(just bought it). where would i get a cv type u-joint? thanks for the help. and no i havent lowered my transfer case, wouldnt that effect my front driveline angle though?
     
  6. Chaddy

    Chaddy 1/2 ton status GMOTM Winner

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    it would effect it in a good way. you need longer d-lines too
     
  7. BrownK5

    BrownK5 Registered Member

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    what do people use to space there trany x-member? i dont really want to lengthen the drivelines because i cant really afford it, so the cheaper the solution the better.
     
  8. midnitewarya

    midnitewarya Sounds like a problem for future me. Premium Member

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    Actually, on a K5 lowering the t-case is the only thng that doesn't cost anything. If you look at the x-member that holds the t-case and look at where it bolts up to the frame, you will see that there is two bolts on each side. Look closely at those bolts, either above or below the framerail you will see that a 1" sleeve is on all of those bolts. Just take the bolts off and put the sleeve between the framerail and the x-member, and walla! You loweed your t-case 1" with the already included OEM hardware!

    As for getting a c/v shaft, you will have to modify your t-case output shaft so that a c/v can bolt up to it. If you have an np241, this means getting rid of the slip yoke.

    Al
     
  9. muddybuddy

    muddybuddy 3/4 ton status

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    ive got a slip yoke cv driveshaft from High Angle Driveline
     
  10. MNorby

    MNorby 3/4 ton status Premium Member GMOTM Winner

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    Just a noob question but I have seen it done before. The blcoks have a taper. I've seen people not pay attention and install the block backward so it was actually pointing the pinion down more. That will cause hella problems.
     
  11. Leper

    Leper 1/2 ton status

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    Why do you say that? I did not drop my transfercase because of the angle in the front I would have had.


    FYI...... I have seen a bunch of stuff about keeping the angles matched. I have also seen a bunch of trucks that aren't done that way and have no vibration. My sons for one. As of tomorrow mine will be the same. The worst vibration I had with the dshaft was when the angles were exact. I understand the physics behind the angle theory, but I have seen many times where it is not a noticable vibration and a truck that ate ujoints up in 2 months go to 8 months.

    I am not trying to start an argument, just telling what I have seen.
     
  12. BrownK5

    BrownK5 Registered Member

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    I am positive I installed the blocks correctly. I just want to know why it already makes a clunk noise sometimes when i take off from a stop. the new ujoints have been in for literally not even 2 days and i havent driven it as much as usual because of the fact.
     
  13. my87Half-ton k5

    my87Half-ton k5 Registered Member

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    on this note i have an 87 k5 it looks lifted about 5 inches and the transfer case may be lowered im not sure..i bought it that way
    the motor does sit down in the back a bit
    anyways all my mounts seem tight on the motor and tranny but i have some vibration under hard(er) acceleration...its enough to rattle the truck anyways..only when your foot is on the gas or off the gas esp over 50...i havent actually checked my ujoints yet but they arent squeaking or anything...should i worry or not? andas far as checking driveshaft angle how do i do it? i have an idea of what that angle should look like in my head i would imagine 32 degrees is pretty radical...is the vibration normal though?
     
  14. my87Half-ton k5

    my87Half-ton k5 Registered Member

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    btw im running 33 inch bf goodrichs turbo 350 trans and i believe the chain driven TC (the 208?) im also not sure what the blocks should look like...mine are square no angles.
     
  15. BrownK5

    BrownK5 Registered Member

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    ok, so ive dropped my tcase 1" and ground down the front end of the rear driveshaft so it doesnt hit the tranny yoke. i replaced the front u joiunt for thr FOURTH time. it still makes noises like it did before right before it blew up again. im thinking its not my driveline but something else. any ideas???
     
  16. BrownK5

    BrownK5 Registered Member

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    so today i went to the local 4x4 shop and they said that my angles are fine. however my driveline decided to blow out again today. btw i have a 203 t case. what should i do?
     
  17. sandawgk5

    sandawgk5 3/4 ton status

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    Sounds like with your blocks you are getting mad axle wrap and that is causing the joints to bind and subsequently break.

    Ira
     
  18. Chaddy

    Chaddy 1/2 ton status GMOTM Winner

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    Have you had your D-L balanced? Are the ears-weld yokes ok? I had a bad ear on an old D-L and it went through a couple joints, then I took it down to the shop and they spun it and it was all out of wack so they welded on new yokes and put spicers in it and it was great.
     
  19. 1977k5

    1977k5 3/4 ton status Vendor

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    I would not recommend using the stock "spacers" to drop the t-case. That is just begging for the frame to crack in that area (the spacers are not wide enough). Blocks make for some crazy axle wrap. First thing I would do is check to make sure your u-bolts (the ones that hold the axle) are tight. If that doesn't work, the solution is either to get real lift springs or to make an anti-wrap bar (custom fab., plus it would probably interfere with the stock gas tank).
     
  20. 1977k5

    1977k5 3/4 ton status Vendor

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    BTW, Chaddy your avatar is freakin' crackin me up as I sit here listening to Pantera.:D
     

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