Highway speed vibration from rear end

Discussion in 'Got gears?' started by hobbby, Apr 29, 2015.

  1. hobbby

    hobbby Well-Known Member

    I've had a vibration above 60 MPH I'm trying to troubleshoot.
    I took a video running it on jack stands. I removed the wheels/tires/drums to eliminate those variables and the vibration persists.
    I've replaced the following that had no effect on the vibration, Transmission 2004r, drive line, both u-joints, new 3.55 gears and carrier, all new rear end bearings.

    Take a listen/watch of the video let me know what you think I'm stumped.

    [video]https://youtu.be/nOgZTymRX2w[/video]
     
  2. 69GS400s

    69GS400s ...my own amusement ride!

    Not saying this is your issue but ..

    .. I chased the same problem for years with my BigRed. New wheels/tires verified on another car to run vibration-free @60mph but vibrated on BigRed. New U-joints, driveshaft (and then driveshaft checked at another shop for trueness and balance), axles checked for true-ness .. basically everything except -

    When changing gears from 3.08 to 3.31 in my 12-bolt the mechanic informed me that the pinion yolk where the rear U-joint sits in had excessive play - new pinion yolk and 3 year problem finally solved. It wasn't noticeable to me .. it seemed to bolt in and snug down fine ..

    Just something else to check. Have you had your driveshaft checked for trueness and balance ?
     
  3. hobbby

    hobbby Well-Known Member

    The yoke is one of 3 rotational parts that has NOT been replaced. The other two are the axles. Think if I take the yoke off the driveline shop could check it for straightness?

    Two weeks ago I had a 2004r installed with a new balanced drive line and new u-joints. I was hopeful the vibration would go away after that upgrade but it remained exactly the same.

    Right before I purchased the car two years ago the car was getting a dyno tune and wadded up the drive line. Anyone ever bent a yoke?
     
  4. gstewart

    gstewart Well-Known Member

    I solved the vibration in my drive train which the car has had for years. Turn out the driveshaft had a slight bend. Solution was new driveshaft.
     
  5. 72newbiebuick

    72newbiebuick Gold Level Contributor

    Gerry you said the driveshaft had a slight bend in it - was it balanced and if so did it "pass" even though it had the bend?

    Mark
     
  6. hobbby

    hobbby Well-Known Member

    How violent was the vibration in big red? Mine is pretty bad shakes the center console visibly.
     
  7. 69GS400s

    69GS400s ...my own amusement ride!

    Cruisin down the highway @ 65-70 not too bad but any higher for long periods was annoying (and you know you're not doing the suspension any favors ..)

    .. at the top of the quarter it was almost scary and I didn't race it much for a few years until solved
     
  8. hobbby

    hobbby Well-Known Member


    This is an exact description of what I have going on. 80+ make my eyes vibrate and I wonder whats going to fall off. 65 and under is tolerable but still quite noticeable. I took my yoke in and had it inspected they said it did indeed have excessive tolerance where the u-joint sits. Should know by the end of the week I ordered one from OPGI.
     
  9. DauntlessSB92

    DauntlessSB92 Addicted to Buick

    Have you checked your driveline angle? The 2004r has to be moved up to where it almost hits the floor in order to get the angle close to correct. Adjusting the pinion angle won't make up for the transmission end if it's too severe
     
  10. schlepcar

    schlepcar Gold Level Contributor

    The yoke would probably be noticeable if if were shaking that much. If you run it up to 60 mph check to see if the driveshaft is true to your line of sight. If you see ANYTHING that looks like a wobble it's because it is. If not, make sure your axle shafts are true when they are free spinning. It really sounds more like a shaft issue.
     
  11. gstewart

    gstewart Well-Known Member

    it was checked for balance and was okay but on the balancer u could see the wow. Several/many $$ later and i had a new driveshaft.
    I know that the driveshaft was original as u could see a very faint coloured ring on the shaft.
     
  12. hobbby

    hobbby Well-Known Member

    Just following up with what I found.

    I Replaced the pinion yoke but the vibration remained the same. So I removed one axle at a time and ran it on jack stands. Neither axle showed any improvement meaning it had to be the in the drive shaft, pinion, or carrier. Removed the carrier and ran it again just on the drive shaft and pinion, same vibration.

    Removed the brand new drive shaft and took it to a different shop for testing. The guys exact words... "Did you run this in your car, must have been one hell of a wild ride" He's going to get it all straightened out and I'll have it back on Monday.
     
  13. hobbby

    hobbby Well-Known Member

    The new drive line made the vibration much better but not 100% I was giving a friend a ride to show him the vibration and get another opinion. We had just accelerated up to 80 or so and started to decelerate when this happened. I'm at a total loss can't imagine what the issue could be. Again the transmission, rear end, drive line, and all u-joints are new. Could this be some sort of binding going on because of drive line angle?

    [​IMG]

    [​IMG]
     
  14. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Wow! Checking the drive line angles is very easy with a very inexpensive angle finder available at Sears. You have something serious going on there. Do you have the stock rear or was it changed?

    http://www.buickperformanceclub.com/Pinion.htm
     
  15. hobbby

    hobbby Well-Known Member

    I threw in the towel and towed it to the local drive line shop. Hopefully they figure it out. I'll post back with the findings.
     
  16. hobbby

    hobbby Well-Known Member

    I read through the link you sent Larry. If anything I have little to NO pinion angle. How bad would that scenario be?
     
  17. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Under power, the nose of the rear moves up, so it can bind under power. Usually what happens is it wears out the tail shaft bushing of the transmission, but I suppose if the bind is bad enough, it can damage parts. Note the last paragraph in that link,

    " Also, excessive pinion angle is
    often the real culprit behind broken parts. Racers love to attribute
    busted driveshafts, exploded tailshafts, and cracked bellhousing to
    the raw torque and horsepower produced by their motors, when in fact
    it's usually a problem with driveline geometry. It's definitely
    worth checking before you break something expensive. See you in the
    lanes!!"
     
  18. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

  19. hobbby

    hobbby Well-Known Member

    Worse yet I think my transmission and the rear end are pointed slightly towards the ground. I thought this was a really cool video explaining driveshaft angle examples...

    [video=youtube;gmV4qwLfOMY]https://www.youtube.com/watch?v=gmV4qwLfOMY[/video]
     
  20. DauntlessSB92

    DauntlessSB92 Addicted to Buick

    I'm still pretty confident you should try shimming the Trans mount. I had the exact same problem as soon as a switched to the 2004r. I put a few washers under the Trans mount and that fixed it. Like Larry said, a cheap angle finder will tell you where you are at
     

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