e2r

Oops typo: aft: 225/50 ZR 16 92 W. Much better than 205/50's I think. So the same size as the Potenza's. I trust you on that 245's are better and I probably need to change these tyres, but can the tyre size aft cause those vibrations?? ((Maybe you could test it when you're in the neighbourhood??)

((I didn't see your car. My car was there for some days because they had to send the catalyst to the dealer from whom I bought the S2k. Good to hear that Welman has more experience with S2k's!!!))


e2r

SpitfireS

Please read my last post again.
I've edited it and asked (yet) another question.


e2r Posted on Aug 23 2006, 10:31 PM
I've send you a PM (personal message)

The link to it is top right of the page =>PMs

e2r

I checked it and the rotation direction is OK. So I beginning to fear that xviper was right from the start and it is something expensive like wheel-bearings...

The current tyres I will change when I buy wintertyres for these rims (in november) and (probably) the 2004+ rims for new summertyres next spring. But a good tip, thanks!!!

I rechecked the state of the tyres and it doesn't look like they separate. Maybe I need to get the whole wheel off to check it all.

I will call the Welman mechanics tomorrow morning...I really hope that it isn't a serious problem....

E2R

RACER

Unless you have a defective tire(s), it is very unlikely that a 225 width tire will vibrate. You mentioned that they are in fact Summer tires, so unless you have a defective tire, something other than your tires are causing the vibrations.

RACER

It's hard to say without actually doing hands on investigating. A wheel bearing is not something to put off when it become worn out. One thing you can do is to grag your wheel at the top with both hands and try to shake it as hard as you can. If there is substantial play in the bearing, it should show in this test. Another thing you can do to check for notchyness is this. Jack up car, remove wheel from corner of car that you want to inspect, revove brake pads and turn the hub by hand. If there is any notchyness, it will show up here. You can also grab the wheel on both sides with each arm and put pressure on it back and forth to check for play, but I think most street cars will have a small amount of play in it anyway.

Note, with the car jacked up, keep legs away from underneath the car while doing any shaking.

RACER

Actually, if there are any worn parts like maybe a ball joint or something, that would show up by doing this as well. It sounds like a job for a good alignment tech.

SpitfireS

It's the 20 minutes warm-up it needs that makes me think its bearings.
Or brakes (parking brake not releasing properly)
Or rear shock absorbers?

RACER Posted on Aug 23 2006, 11:04 PM
[QUOTE]QUOTE (SpitfireS @ Aug 23 2006, 01:01 PM)
We should get a room...

RACER

e2r

RACER thanks for your advices! Tomorrow I will make a call to the mechanic AND will try the things you wrote.

xviper

Check out the sticky at the top of the wheel/tire forum to see why you would go with 245 tires on the rear when going with non-OEM tires.

As for the wheel bearing, if that's what it is, there is also another way to possibly rule that out (or not). A bad bearing that heats up that badly to cause that much vibration is going to get very hot. Once you reach the point of vibration, try to slow down as best you can without using too much braking. Pull over to a safe place and shut the car off in gear and ebrake only lightly pulled. Now go out and carefully feel the center of the wheel hub that you can reach through the spokes of the rims. Don't burn yourself. It's not likely that both sides will be worn out at the same time. The bad side will be a lot hotter than the other side. If there is no difference, then it's less likely to be wheel bearings. If one side is much hotter, you have your answer.
If it were the brakes causing this by not fully releasing, it would not likely take as long to get so hot and also, a dragging brake isn't so likely to cause such a vibration at speed. A brake that gets really hot usually grabs less and will begin to smoke. You can also check for this when you come to a stop.
Pitted CV joints will produce severe vibration upon acceleration. Next time your car begins to vibrate, slow back down, downshift and do a brisk acceleration up through the rpm range and through at least one more gear. Is the vibration evident and is it similar and as severe? If not, you may have ruled out the CV.
As a side note, have you checked the torques on your lugnuts? This may or may not have anything to do with what's going on, but you certainly don't want this sort of vibration if the lugnuts aren't on tight.
Like RACER, said, none of these possible causes are anything you want to wait too long to sort out. It's dangerous and best to get it to a mechanic rather than spending to much time experimenting to find out on your own what it might be.