vibration issue

Discussion in 'Suspension, Steering, Brake & Wheel Topics' started by 1981zapper, Sep 28, 2019.

  1. G72Zed

    G72Zed Veteran Member

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    If you use the tires true effective static radius, you might be at 12.250, so a 24.5 tall input, that would bring you to 3,250 RPM @ 63.5 MPH, add in 3-4% converter slippage and your in the ballpark with the tach being off 8-10%.
     
  2. 1981zapper

    1981zapper Veteran Member

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    Yesterday I was following the car and noticed driver rear wheel was wobbling quite a bit at highway speeds, the passenger rear wheel had a wobble too but not as bad as the driver.

    I rechecked all lug nuts torque and nothing came loose


    The wheels are brand new I doubt they are bent or warped, I took the wheels off and visually inspected them, did not see anything damage, the stick on weights are all still present.

    Could my axle be bent? which is causing the vibration / wheel wobble? I measured the driver rear axle endplay with a dial indicator and got 0.034" endplay does that sound right?
     
  3. G72Zed

    G72Zed Veteran Member

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    I remember way back when I had the C clips it was around .005-.015 or so, does no look like allot in your case, but showing wear.

    Put the dial indicator on the outer axle flange, it may indicate you have a bent axle.
     
  4. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    A new set of wheels finally took care of my pesky vibration, unfortunately it was the last thing I did. I called a company that straightens wheels, they didn't want to mess with the stock steel 5 spoke, said once the centers warped, they were toast. I did everything that's been suggested here, and more.

    And, after a rebuild and calibration, my factory tach is still high, compared to the Eddy Pro 4 readout. I trust the Eddy readout, it matches the shift light.
     
  5. jamieg285

    jamieg285 Veteran Member

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    My vibration turned out to be a cracked flex-plate. Bear of a job to swap. I did mine with the engine/box still in the car, just pulled the box back - didn't help that the on first attempt I mounted the plate backwards and had to do it again.
     
  6. scrap--metal

    scrap--metal Member

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    The driveshaft could be out of balance, even if the weights are still on both ends. I'm not sure how that happens, but it happened to the factory driveshaft in my '79.

    I fought the vibration for a long time (wheels/tires, rear end components, axel bearings, brake drums, etc.) before messing with the driveshaft. Got it balanced and then the weight they welded on fell off in the garage while I spun it up on jack stands. I welded it back on in the same position, but with a quality weld. My vibration is almost gone now, and I suspect what's left is due to the fact that I really welded the weight on there and inadvertently added more weight with a better/stronger weld.
     
  7. steve vuk

    steve vuk Vuk

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  8. steve vuk

    steve vuk Vuk

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    I had the same vibration issue with my second 1979 z28 changed everything and it's mother ...at 55 it would shake the rear view....after I sold the car to a friend ase certified mech he was dumb founded also ...it turned out to be the harmonic balancer
     
  9. cadillac_al

    cadillac_al Veteran Member

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    If you can see a wheel wobble that can't be good. I would think that would be more of a run out issue with the axle. I had a guy tell me once his car got bent axles from being cinched down too tight by a transport company. I never quite believed it but he did change his axles and claimed it fixed it.
     
  10. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

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    If you think it's a warped drive axle, swap the wheel to the front and spin it by hand with a can next to the wheel. You'll see right quick if it's the wheel or the axle. I've warped or twisted axles before but never the flange.
     

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