vibration issue

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

  1. 1981zapper

    1981zapper Veteran Member

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    Ever since I've owned my car its always had a vibration issue at highway speeds, I figured it was from the worn out suspension and 30 year old tires, at 3500 RPM the steering wheel and dash shake like you would not believe.

    Anyways I finally got around to installing all new, Suspension bushings, ball joints, inner / outer tie rods, center link, idler arm and new rims and tires

    Today I got my tires/ rims installed and got an alignment done, the drive is a lot better but I still have a vibration issue at 4000 RPM and up

    One thing to note:

    I've always wondered why, my car revs so high on the highway, I have 3.73 gears, turbo 350 (non-lock up) and 275/40/17 (25.67")

    At 63 Miles per hour I'm revving around 3650 RPM, which from my online calculator with my set up I should only be revving at 3,076 RPM
     
  2. Twisted_Metal

    Twisted_Metal Administrator Staff Member Lifetime Gold Member

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    Are you sure you have a V8 tach?
    Do you have the correct speedometer gears for a 3.73 rear?
     
  3. COPO

    COPO Veteran Member Lifetime Gold Member

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    I kept my 80 Z28 for 10 yrs before selling it and never had a vibration issue. Maybe the driveshaft balance weight came off or you have a loose flex plate bolt or the universal is shot.

    IMG_2528.jpg
     
  4. 1981zapper

    1981zapper Veteran Member

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    its the factory z28 tach

    no I do not have the correct speedometer gears, as my speedo is off, I verified my speed with my Garmin GPS
     
  5. 1981zapper

    1981zapper Veteran Member

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    I had a look at the driveshaft still has weights on both ends of it, u-joints are tight
     
  6. COPO

    COPO Veteran Member Lifetime Gold Member

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    Ever check the pinion angle?
     
  7. 1981zapper

    1981zapper Veteran Member

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    No, I will have to check it out over the winter
     
  8. Gary S

    Gary S Administrator Lifetime Gold Member

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    These cars never had vibration issues when they came off the assembly line. Knowing that, look over the car carefully for any drivetrain part that isn't original as some change along the way is likely the problem.
     
  9. shanghai Kid

    shanghai Kid Veteran Member

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    Give them motor mounts a looksee
     
  10. rchydzik

    rchydzik Veteran Member Lifetime Gold Member

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    With respect to the RPM, you will get some slip with the torque converter (100-200 rpm), but more likely the tach is reading fast. This seems to be very common. Mine was about 10% off reading fast.
     

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