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Discussion Starter · #1 ·
I have the Michelin PS2s with 16k miles on them. They still have a good bit of tread left on them. However, I feel an odd wiggle in something at times. Its as if a tire is low, a wheel is loose or tram-lining is occuring. It is more noticeable when cold or on bumpy wavey surfaces. I've checked the obvious things (tire pressure, wear patterns, lug bolts, etc). There is no vibration in the steering wheel and the brakes are smooth.

Has anyone rotated the PS2s side to side? They are not uni-directional but do have a specific inside/outside. After my last track day, I reversed the tires from left to right due to more wear on the left front and scaloped edges. I ran a session or two on the PS2s at the track. They felt good and I quickly equalized the outside edge wear. :)
Might it be a belt going bad from rotating them?
Might I have a shimmy from a thrust bushing or something starting to go bad (at 52,000 miles)?
Any other ideas?

PS: My only complaint with PS2s at the track is they don't make much noise at their limits. They were actually harder to judge break-away than the R compound Kuhmos.
 

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its more than likely the tire not holding temperature enough to cause it to fill out..i have the same issues with my toyos when 60 and below and raining or when below 55 with nothing.
 

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Discussion Starter · #3 ·
Anyone else with thoughts on this? Especially on what I'd feel if the thrust bushings, etc are wearing out?
 

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Richard, How are you doing? Going to Grand Prix again?

Are you sure you aren't getting some feathering or roughness/uneveness on the outside of the front tire treads? This usually results in what you are experiencing. I also have PS2s, but haven't noticed this. Maybe the control arms, but I think you would be hearing noises by now if that was the case.
 

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Richard in NC said:
Anyone else with thoughts on this? Especially on what I'd feel if the thrust bushings, etc are wearing out?
When my thrust bushings started to go, I only felt it on braking and then most noticable under hard braking. Otherwise, the car drove fine and the car tracked straight. Not sure how much that helps.
Regards,
Jerry
 

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Richard in NC said:
Might I have a shimmy from a thrust bushing or something starting to go bad (at 52,000 miles)?
I can't speak to the PS2s (I'm still on my last set of Tire Rack OE Viper PS1s), but I can share my experience with bad thrust arm bushings.

I just replaced my original set at 77K miles (~3K track) with PowerFlex aftermarket units.

When I first started noticing some front wheel/steering wheel shimmy, I took off both fronts for a high-speed balance. The tire tech noticed some feathered wear patterns--one indication of thrust arm bushing failure.

I then noticed a more pronounced shimmy under braking (hard braking at first, then pretty much any braking between an indicated 50-60MPH).

Thrust arm bushing replacement cured everything.

Hope that helps!
-Dave
 

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Richard in NC said:
I have the Michelin PS2s with 16k miles on them. They still have a good bit of tread left on them. However, I feel an odd wiggle in something at times. Its as if a tire is low, a wheel is loose or tram-lining is occuring. It is more noticeable when cold or on bumpy wavey surfaces. I've checked the obvious things (tire pressure, wear patterns, lug bolts, etc). There is no vibration in the steering wheel and the brakes are smooth.
Rirchard I think belts have shifted in one of your tires and it giving it a little hop. That might be what you feel. The best time to feel this condition is on a smooth surface at about 10 to 20 mph. If you feel it in the steering wheel it's in the front. If you feel it in the seat of your pants it's in the back.

Joe
 

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Teutonaddict said:
When I first started noticing some front wheel/steering wheel shimmy, I took off both fronts for a high-speed balance. The tire tech noticed some feathered wear patterns--one indication of thrust arm bushing failure.

I then noticed a more pronounced shimmy under braking (hard braking at first, then pretty much any braking between an indicated 50-60MPH).

Thrust arm bushing replacement cured everything.

Hope that helps!
-Dave
Dave your right the thrust arm or radius rod bushings are common on BMW's. It feels like the front wheels are out of balance or the brake rotors are out of round. Man those front ends are sensitive.


Joe
 

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