ScottMellor

Maybe you-all can help me figure this problem out:
(I have already done a search on steering wheel shimmies)

I recently got a new set of Pirelli Corsas in 235/295 and had them mounted on my FIKSE FM-10s 8.5/11. I took my P-Zeros off of the FIKSES and mounted them on my hollowspokes. The tire guy, (Bavarian Performance) does a super nice job, REALLY cleans the wheel and then marks the tire and the rim with a wax marker to make sure the tire has not spun on the wheel.

I then took the car to Westend Alignment for a corner balance and alignment. Another super careful job, with me sitting in the car for 4 hours while he does his thing. I plow home up the 405/101 and all seems as well as can be expected in rush hour traffic.

Two days later, I notice a steering wheel shimmy that occurs at 55-58 mph.
It happens while accelerating/decelerating or at steady state in that speed range.

I took it back to the tire guy and he checks the balance, finds it a slight amount off and redoes the balance.
Shimmy is still there.

I took it back to tire shop and they re-did it again.
Shimmy still there. Tire guy says he suspects either a bent wheel or a castor problem with the alignment or a bad tire. He did say that left front FIKSE appeared to have a slight ding on the bead seating area.

I went home and popped on my hollowspokes with the P-zeros that came off of the FIKSEs.
Smooth as a babies bum.

I then popped on the front right FIKSE/CORSA.
Smooth as a babies bum.

I then pop on the left front FIKSE/CORSA.
Shimmy back.

Now, I had no shimmy with the FIKSE/Pzero combination, and I have not hit anything recently, so I don't think that the bent wheel theory is the conclusion I would reach at this time. Nor do I have any reason to suspect an alignment issue

Any ideas? I'm starting to think that I might have a wonky tire. I intend to do a "canyon heat cycling" this weekend and see if anything changes.

Bradford

Scott,

If you are going to do your "canyon heat cycling" toward the beach Sat. let me know. I can follow and only hope to stay close. Where are you in T.O.?

Scott

ScottMellor

I normally get up early and potter around Mulholland or Decker or something, and then go and watch the crazy motorcycles pulling 200 yard wheelies at the lookout above the Rock Store.
I'm very easy to keep up with. Sometimes a couple of us meet for Breakfast at Jacks. I'll give you a shout if I do.
(I live in Lynn Ranch.)

CP

Scott,

Are the CORSA uni-directional tires? If they are, check if the treads are facing the 'right' direction.

I have a similar issue with my M5 now, and I'm having the balance checked tomorrow.

CP

ScottMellor

CP: Yes they are unidirectional.

All tires are on the correct sides.
The valves are opposite the red stud and I have no locking nut.

SteveL1

Why not take the suspect tire back to the dealer and ask them to swap out for a new one. Agree to pay for mounting and balancing IF the problem does not go away. If it does go away, they can return tire to the mfg. for credit. Just another option. If you do put a bunch of miles on it and the problem continues, you may have a harder time getting them to do anything.

If they swap out and the problem is still there, you now know it's a wheel and it cost you $25 to find out.

kkim

try having the tire rotated on the rim by 180 degrees. Might be some sort of harmonic vibration of the rim/tire combo.


Good luck!

ScottMellor

Tire came from TireRack.

I have heard of spinning it on the car, but remember its AWD.....
I'm leaning towards sending it back to Tire Rack.

volpenyc

Another idea - have you had any road "incidents" (pot-holes, curbs, etc.) recently? I thought had the same problem with my PZero's, then I found a sidewall blister (ouch!)...

Derrick B.

Just an off the wall question, but have you double checked the tire pressure on that one wheel?

ScottMellor

Thanks for all the input guys.
No recent road incidents and tire pressures are right on the money.
I just got back from a solo early morning canyon run and, although the car drives beautilfuly in the twisties, the shake at 55 is like it's possessed by Charo.

TT Gasman

I had a similar issue with my 996 recently. Ordered a set of Michelins from TireRack, during the mounting/balancing one of the front wheels appeared to be bent. Mind you the car had zero symptoms that would indicate a bent wheel prior to the new tires, but now there was a serious vibration/ shimmy at speeds over 60 mph. I took the car back a few days later to the same dealer to have the wheel repaired, then I received a call that the wheel was not bent and they could now easily balance the suspect wheel/ tire. The car feels perfect now, smooth as glass all the way up to 130mph on the track.
To this day I am perplexed by this turn of events. Could the tire have been out of round or deformed from shipping?? You might try having the tire mounted and balanced again before you send it back to TireRack.

nman413

Scott, have you tried flipping the wheels left to right to make sure it's not something else?

ScottMellor

The tires are completey unidirectional, so I can't flip sides. I could swap sides with the wheels and then re-mount the tires on the other wheel to rule out a wheel problem, but there was no problem with the P-Zeros on those wheels.
Also, if the wheel were tweeked, would not the problem most likely be apparent at all speeds? It goes away anywhere other than 55-58.

adsc4s

Scott, I had the exact same problem with Pzero Assymetricos. It ended up being a bad front tire for me. Tire was out of round.