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driveline vibration - AGAIN!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Jersey, Apr 9, 2002.

  1. Jersey

    Jersey 1/2 ton status

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    sorry, i know this topic has been covered before about a zillion times but..here it is anyway /forums/images/icons/smile.gif 4" Rancho lift - front springs, rear blocks - lowered T-case, new 35" Mud KO's all nice and balanced, new ujoints on stock rear d-shaft, new tranny mount. The vibration was there with my old tires and still with my new so i can rule them out. The only thing i can think of is that i've heard if the angle of the front ujoint on the rear d-shaft isn't the same or damn close to the rear ujoint of the rear d-shaft, that you'll get vibes. The rear blocks have a taper to them which tips the pinion upward reducing the angle for the rear ujoint. dropping the transfer case with the stock spacers changes the angle to both the front and rear ujoins on the rear d-shaft the same. no? i think i'm thinking right. /forums/images/icons/smile.gif This is just about the only thing i can think of that could be causing the slower bouncing vibe i get after around 25-30mph, is the angle difference. how do i correct this? any other suggestions? Thanks for help in advance.

    - Jersey
     
  2. TopOff

    TopOff 1/2 ton status

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    Are the shafts balanced?

    I first got my rear made for 1-ton yokes. After 300 miles the weight for the balance came off. Luckily mine was easy to spot as I got the driveshaft unpainted. I painted it.. then when the weight came off it was very easily identified.

    Yes the driveshaft company balanced it for free...

    Good luck.
     
  3. Jersey

    Jersey 1/2 ton status

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    The problem is - i pulled an 18 hour shift on my (stock) truck and put in the 4" lift, 14FF, D44 and the new rims and tires, using the old driveshafts. I didn't have any vibrations before the long day/night. I completely rebuilt both axles before i put them in but now i'm wondering if it could possibly be a bent axle? i would doubt that a 14ff axle could be bent but anything is possible i guess. maybe i should rotate the driveshaft 180degrees and bolt it back up to the yoke? i don't know. just guessing. it seems most noticable around 45-60mph if that helps. thanks for the info.

    - Jersey
     
  4. BorregoK5

    BorregoK5 1/2 ton status

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    I flipped my driveshaft so the compression yolk was on the axle side and had completely different vibration characteristics (for the better). I've been playing with the angles quite a bit.. the closer I got to having equal angles at the tcase and the axle side, the fewer vibes I had. I had the same tapered lift blocks which pointed my pinion up toward the tcas but not all the way... I ended up flipping mine backward to bring the pinion down to reduce the vibrations but it never went away completely... kept blowing the tcase ujoint too due to vibration. I just recently took a front CV driveshaft and retubed it along with making a mating bracket for my rear tcase yolk and all the vibes are gone. You'll want to look at u-joint angles, loose compression yolk, wearing u-joints(shaft unloaded), bent driveshaft (even a ding), tight bolts all around (not too tight on the u-joint straps though!). Hope that helps.

    Had a second thought as well, I had a bent steelie rim which was difficult to get balanced when I swapped my tires.. so don't discount the wheels if there is a lot of weights on one of them, may have thrown one too.
     
  5. Jersey

    Jersey 1/2 ton status

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    Thanks. i guess the only way to get the front angle out of the Tcase and the rear angle at the rear is to swap the block around. dropping the tcase changes both angles respectively. i think if i could just tip the tcase down pointing ay the rear, all would be good, but obviosly cant do that! guess i'll just have to mess with it as you've been to figure it out. Thanks for all the info Borrego. appreciated.

    - Jersey
     
  6. redrightthand

    redrightthand Registered Member

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    C.V. joint fixed my vibration problems, but I had vibration only on take off not at driving speed.
     

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