Steering wheel shake....

[That986]

Well it turns out that one of the mechanics who did the alignment 6 weeks ago is blind as he couldn't spot a failing tie rod. The wheel grab checked confirms it, rocks about (a lot now after ramming it over a couple of sharp speed bumps) when you grab at 9&3.
I'd ruled this out as the car had been gone through mechanically at the beginning of September with the instruction to replace anything that looked worn or tired, obviously this was never looked at.

I'm super annoyed with these guys as i was about to start looking at other wheels and running round to see if i could get more tyres tried out when it is exactly what i thought it normally is when you feel that kind of shake.

Anyway, the car is now booked in at the local garage to have all the inner and outer rods replaced (if one has gone, the other is never far behind) and then align it again.

Thanks for the advice guys.

[jayspeed999]

Originally Posted by That986

Well it turns out that one of the mechanics who did the alignment 6 weeks ago is blind as he couldn't spot a failing tie rod. The wheel grab checked confirms it, rocks about (a lot now after ramming it over a couple of sharp speed bumps) when you grab at 9&3.
I'd ruled this out as the car had been gone through mechanically at the beginning of September with the instruction to replace anything that looked worn or tired, obviously this was never looked at.

I'm super annoyed with these guys as i was about to start looking at other wheels and running round to see if i could get more tyres tried out when it is exactly what i thought it normally is when you feel that kind of shake.

Anyway, the car is now booked in at the local garage to have all the inner and outer rods replaced (if one has gone, the other is never far behind) and then align it again.

Thanks for the advice guys.

Was this problem ever solved? I just picked up a 2001 "S" and experienced the same thing. It does not happen every time I go over 75 mph. However, this is the same situation that occurred with one of my prior cars, a BMW 740 Xi. I learned what caused the vibration with that car: Cold, slightly squared tires.

Specifically, when I would park in my office's parking garage and leave it there for 8 hours or so, the tires would cool down a lot as it was colder in the garage than outside. Most of my drive home (around 17 minutes), I would experience the vibration.

However, if I parked outside my house in my driveway, then drive the car, there was no vibration at all above 75 MPH. I experienced the identical thing today with my Boxster: Yesterday after parking in the parking garage, I had vibration. But this morning, after sitting in my driveway with sun, there was no vibration detected above 75 MPH.

YMMV, but this has now been consistent and I think that in my case, this is the cause of the vibration. I believe that when the tires get cold, they retain the slightly flat or "square" shape where the tires contact the cold concrete. I believe the "squared" tire is the cause of the vibration. That is why the vibration does not occur when sitting in my driveway in the sun: the tires do not get cold enough to "square."

[BYprodriver]

Originally Posted by jayspeed999

Was this problem ever solved? I just picked up a 2001 "S" and experienced the same thing. It does not happen every time I go over 75 mph. However, this is the same situation that occurred with one of my prior cars, a BMW 740 Xi. I learned what caused the vibration with that car: Cold, slightly squared tires.

Specifically, when I would park in my office's parking garage and leave it there for 8 hours or so, the tires would cool down a lot as it was colder in the garage than outside. Most of my drive home (around 17 minutes), I would experience the vibration.

However, if I parked outside my house in my driveway, then drive the car, there was no vibration at all above 75 MPH. I experienced the identical thing today with my Boxster: Yesterday after parking in the parking garage, I had vibration. But this morning, after sitting in my driveway with sun, there was no vibration detected above 75 MPH.

YMMV, but this has now been consistent and I think that in my case, this is the cause of the vibration. I believe that when the tires get cold, they retain the slightly flat or "square" shape where the tires contact the cold concrete. I believe the "squared" tire is the cause of the vibration. That is why the vibration does not occur when sitting in my driveway in the sun: the tires do not get cold enough to "square."

Thanks for searching ! Sounds like you are on to the problem. Most ultra-high performance tire can "flatspot" when cold as you have discovered. If the tire uses nylon for tread belts it is more likely since nylon expands & contracts greatly with temperature extremes. Read your sidewalls it should list tire construction materials for tread & sidewalls.