Quote:
Originally Posted by javadog
If you see some motion that isn't perfectly concentric and round, time to mount a dial indicator and check for runout. Start with the wheel, then the brake disc, then the hub, etc.
For phase changes in vibrations, look to the other wheels. Two possibilities: two wheels of the same diameter turning at different speeds (like left and right side tires in a gentle turn) or two tires of slightly different diameters (worn vs. new, or front versus rear when different sizes are run front to back.)
I don't think this is down to the pavement. You have something that isn't round and probably also something that isn't balanced.
Make sure you look at the backsides of the wheels when they turn. Most runout from impact damage is on the backside.
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I'll have to noodle on how to get a dial indicator positioned so that I can measure the wheels on the car. Open to all ideas - - I have indicators and mag bases. Brake disc and hubs seem more manageable to measure
Regarding rotational size difference - - I did sort of test that - - maybe. When I mentioned that I played with tire pressures, I did one side at 30psi and one side at 50psi. I expected maybe the cyclic rate would change as the tires now rotated in and out of phase at different speeds. But I sensed no difference in vibration.