Vibration at high speed help please.

Discussion in 'Troubleshooting & Diagnosis' started by L Holmes, Jul 24, 2014.

  1. L Holmes

    L Holmes Member

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    Oct 4, 2009
    Virginia
    Been doing a mechanical restoration on my 67 Camaro for the past few years and have replaced the motor, rebuilt the Muncie trany, new custom drive shaft, new clutch and flywheel, rebuilt the 12 bolt posi including new axels & ring and pinion, new wheels and tires.

    Problem is the car has a harmonic vibration at higher speeds in 4th gear. Have tried adjusting pinion angle with wedges made for this but the problem still exists. The pinion angle didn't look or measure bad to start with but I was trying anything. The motor mounts are new and correct for the car /motor combo. The trans output shaft is about 3 degrees up and the pinion is about 2 degrees down at this time. I had the drive shaft balanced again yesterday just to be sure & have purchased a new pinion yoke today but have not installed it yet. The old one shows some wear but not enough to say its bad but I'm grasping at straws at this point.
    Would like some thoughts from others on what to check. Really at a loss as far as what to check next. The vibration does not go away when the clutch is pushed in and it comes in around 55 mph in 4th gear.

    thanks in advance.
     
  2. harbone66

    harbone66 Veteran Member Lifetime Gold Member

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    Feb 15, 2011
    Central Illinois
    Have you had the wheels road force balanced?
     
  3. L Holmes

    L Holmes Member

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    Oct 4, 2009
    Virginia
    I have not but its on the list. In fact I nearly did that today but ran out of time. They are brand new though. Tires and wheels. Ralley wheel reproductions made by wheel Vintiques
    thanks
     
  4. Twisted_Metal

    Twisted_Metal Moderator Staff Member Lifetime Gold Member

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    Feb 26, 2004
    Bloomington, MN
    Put it up on jack stands and run it up to speed with the rear wheels on, then off.

    (Put a couple of lugs on so the drum stays put.)

    <edit> Put the jack stands under the axles, not the frame.
     
    Last edited: Jul 25, 2014
  5. lumpy12

    lumpy12 Veteran Member Lifetime Gold Member

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    Sep 16, 2012
    NorCal
    I did that after chasing a high speed vibration, and ended up buying two new axles to solve the problem :eek:
     
  6. L Holmes

    L Holmes Member

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    Oct 4, 2009
    Virginia
  7. ls777z

    ls777z Veteran Member

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    Feb 19, 2000
    Clay,NY
    Is it by chance a convertible ? Do you have all either all solid or all rubber motor/trans mounts?
     
  8. 408maro

    408maro Veteran Member

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    Nov 27, 2008
    San jose,CA
    I'm going through the same thing!! I have to check the pinion angle on mine and see if that's a issue.

    Quick question wouldn't it not matter if wheels were off or on if getting up to speed in air?
     
  9. b17brian

    b17brian New Member

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    Feb 24, 2014
    Crestview, FL.
    When I was looking at new wheels, I read a few reviews of people having problems balancing Wheel Vintiques. Do you have centering rings between the wheel center hole and the hub or discs?

    Brian

    '67 SS/RS 350, Muncie M20, Black with black interior.
    http://s1355.photobucket.com/albums/q713/b17brian/
     
    Last edited: Jul 25, 2014
  10. Twisted_Metal

    Twisted_Metal Moderator Staff Member Lifetime Gold Member

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    Feb 26, 2004
    Bloomington, MN

    If it's a matter of wheel/tire balance or something like a minor ply separation in the tire which throws off the balance at higher speeds... The vibration won't be there with the wheels off the car. Process of elimination here.

    If the pinion angle is the issue, it will still be there as the car is being supported by the axles and the relative angle to the engine will be the same as driving.

    I forgot to note....

    Put the jack stands under the axles, not the frame.

    A wheel balance issue will be quite evident with the wheels on the car and the suspension hanging but you're throwing more variables into the equation by changing driveline angles.

    I don't think it's very safe to spin the wheels with the engine when the car is suspended by jack stands under the frame.

    Knowing the actual frequency of the vibration and the engine/driveshaft/wheel RPM when it occurs is a big clue to the problem but most people can't feel a vibration and tell you if it's 50Hz or 80HZ so it takes some electronic equipment to measure it .
     
    Last edited: Jul 25, 2014

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