Yet another steering vibration question...

[extanker]

my o9 cay will get a steering wheel shimmy at 65 if its cold out and the car sits for a few days,once the tires are up to temp its gone. ive been over 135 mph and the car is very smooth. yours has all the classic clues of tire issues......out of balance,out of round,old and hard,over inflated...maybe get them road force balanced....how good/old are the tires ? OEM rims? spacers?

[Steve Tinker]

Tanker brings up a very valid point re tyres.
Are your tyres the originals or did you change them when you replaced the wheels? If they are the same age as the car, ditch them.
The only real way to identify the fault as being in the wheel / tyre combination is to borrow a set of front wheels from another vehicle. If the vibration remains, you need to dig further.
Front wheel out of balance usually affects the steering wheel, rear wheel out of balance usually is felt through the seat / chassis.

[shlim8]

Hmmm,

the "new" rims are actually original cayman 17" rims. The only thing was the offset for the rear are further out. The front offset for the front is the same. I had all 4 rims tested without tires - spun on a balancing machine without tyres. All straight.

The front tires are brand new Michellin Pilot Sport 3 (not N specs). I do have a mismatch between front and rear tires - the rears are 2yr old Aspec Db. Had not changed them yet as thread >95% and there was no stock for the tire size I needed.

No spacers - had bad experience with them on my 944.

I had checked my tire pressure and the rears were 2 psi off. Got that fixed and the car now feels more fluid and goes around corners pretty balanced in the dry. What a difference the tire pressure makes. But unfortunately vibration is still there. I still have to take it easy in the wet, but that's prob due to the aspect db tires - those things have no grip in the wet.

Looks like I got to find a Hunter Road Force machine locally, heard there one.

Or hopefully when I get the suspension swapped out they'll find a cracked top suspension mount or knocking strut !!!! ha ha...

[shlim8]

I just re-read Steve's post - and yes the vibration can be felt through the chassis too. But at the same time, I do have vibration distinctly directly from the steering.

2 separate problems ?? Hmmm, I'll need to do another interstate run and figure out whether I'm feeling the same vibrations through the chassis and steering.

[tonycarreon]

i have a volvo and the front passenger rotor had to be machined down because - i don't know something - but before that there was a really bad vibration, afterwards it disappeared.

also, you have to get roadforce balancing. i had the tires rebalanced and the shop didn't use the roadforce balance. i made it about 3 miles away before i turned around and made them do it right. night and day difference.

the boxster is so keen to what the road is doing, the tires, brakes, etc. that anything off could make a difference...

[shlim8]

Originally Posted by tonycarreon

i have a volvo and the front passenger rotor had to be machined down because - i don't know something - but before that there was a really bad vibration, afterwards it disappeared.

also, you have to get roadforce balancing. i had the tires rebalanced and the shop didn't use the roadforce balance. i made it about 3 miles away before i turned around and made them do it right. night and day difference.

the boxster is so keen to what the road is doing, the tires, brakes, etc. that anything off could make a difference...

Tony, before u machined down your volvo's brake rotor, did you get vibration when u braked or while travelling at speeds ?

I did have a front caliper that was stuck, had to get the both front calipers rebuilt, so that rotor was noticable uneven, although since the rebuild, the rotor is physically more even now. But no vibrations when braking even before the rebuild, just that the car wouldn't slide down the slight slope down my driveway.

Both front rotors are at about 22 mm so are due for replacements, the pads are almost brand new though... ha ha, prev owner just changed the pads and did not replace the rotors. The rotors are VERY pricey here from the AD here.

The "old" pads are original porsche items, can I re-use them ? Any way to "flatten" them ? There's still at least 90% left.

Although for this time, I'm going to use my new Textar pads with the new zimmerman rotors, since I'm trying to solve this vibration issue !