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      03-22-2014, 12:52 AM   #23
kitw
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Drives: F91 M8, 991.2 GT3
Join Date: Jun 2007
Location: Bay Area, CA

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Quote:
Originally Posted by grantmax View Post
The saga continues.

I had all four wheels ROAD FORCE balanced Wednesday morning. The vibration under 45mph is gone. The vibration at or around 72mph is still there.

Points of interest:
1. Wheels are not bent. Road force balancer confirmed.
2. Tires are not out of round. Road force balancer confirmed.
3. Hub is free of debris. Confirmed with my own eyes during the wheel balance.
4. I was very clear about how the wheels were to be torqued down and watched to ensure the lugs were tightened gradually and in the star pattern.

Fun fact - I noticed last night that at 72mph (or so) turning the wheel slightly can stop the vibration. A quick course correction within my lane or a longer sweeping curve seems to stop the shake. Sometimes.

Le sigh.


Couple of things to try:
  • tighten the lugs fully, with the car in the air. Usually requires someone sit in the car and hold the brakes.
  • try without. I've had bad spacers.
  • anti seize the hub (NOT the mating surface, just the center hub)
  • Try a known good set of wheels.
  • check the hub for runout
  • Rotate the rotor relative to the wheel. (are you on factory rotors? they are balanced, I've seen some aftermarket rotors that were not properly balanced)

I got my 12.5mm Turner spacers to stop vibrating. It was difficult, but it took a number of things, each of which made a slight difference, but only together fully eliminated the vibration. There are a finite number of things that can cause a vibration and you have to use a process of elimination to figure it out. As you've found, these cars are VERY sensitive.

Good luck - I *HATE* vibrations.
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