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Vibration at 85mph....not tires, I don`t.....

Hey folks,

Think. As with other cars I have driven, when the tire vibration starts, should not the steering wheel shake or vibrate at or about the same time....As well the vibration is in the seats and rearward not steering wheel and frontward. Tires are worn on outside edges in front and I have ruled out bent or warped rims with micrometer. The rear belly pan is not on the car as well. Any suggestions as to what this may be? The car is a 1995 993 C2 97000 miles with PSS9 lowered to the bottom and 19`` Ruf wheels. Tires are Bridgestone in back and Michelin fronts.

Cheers and thanks,

M-

Old 08-10-2010, 09:00 AM
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First, check all your tire pressures.
Low inflation can cause a variety of vibrations throughout the vehicle.
Second, check for lumps, bubbles, slipped belts or other tire deformities.
Lastly, balance 'em all.
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Old 08-10-2010, 09:08 AM
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A general rule of thumb is that imbalances on the front are felt primarily in the steering wheel while imbalances on the rear are felt through the seat of your pants.

Also, I'm not sure that two brands/types of tires on the front and rear is a great idea.
Old 08-10-2010, 01:07 PM
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The following should also be checked:

Wheel bearings all four corners. Check for play when jacked up, grab the tire with gloves and push/pull top and bottom checking for play.

Check rear CV for needing rebuild, torn boots loose hex bolts.

Check rear links for play in the bushings.

Very well may be a tire issue, but any of the above will give similar sensation.
Old 08-10-2010, 02:19 PM
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It may be as simple as uneven pad deposits on the rotors.

They would be visible as slight discolorations against the surrounding metal and can be removed using garnet paper, which you can find at any hardware store. Avoid using regular sand paper as it will actually make any deposits (and corresponding vibration) worse.

Worth taking a look at since it's the cheapest potential fix.

Regardless, you need matching tires. I've got a pair of Bridgestone's laying around doing nothing. What model and size do you have on your car? If they match up, they're yours for the cost of shipping - let me know.
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Last edited by Stuttgart951; 08-12-2010 at 09:25 AM..
Old 08-12-2010, 09:23 AM
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Seems likely tires are at issue.

You have different sets on each axle, the tires have different characteristics and these will amplify with age, reduced tread depth, etc. possibly inducing vibration.

Tires can come out-of-round with age and this can induce vibrations.

Alignment can also go out-of-spec with both miles and tire usage, be sure this is spot-on.

Tires today seem to have a greater tendency to delaminate internally than tires made years ago. This will induce unwanted vibrations.

I suspect your answer lies with one or more of the above conditions.

Cheers!
Old 08-18-2010, 10:36 PM
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Tripple Black 86 Carrera
 
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Hi guys, I'm new to the forum, bought my first 911 from North Carolina and drove cross country to CA 6 months ago. It vibrates intermittently while I maintain speed. The vibration will fade in and out. It seems to occur consistently between 45mph and about 130, after 140 I haven't really felt it. When it is gone, it's completely gone, but when it is present, it vibrates the steering wheel, seats and can even be heard from the windows. I have had rear tires replaced and balanced. The front tires were done by a buddy in NC before I bought the car and don't know if he checked the balancing. I did have the alignment done in NC before I left but this didn't take care of the problem. Any suggestions?

Old 03-03-2011, 06:52 PM
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