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Old 12-29-2008, 07:48 PM   #1
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Nasty Shimmy and Shake...

I have a 99 Boxster with 30K miles. She has been absolutely perfect, until yesterday. Over 60 MPH, the car felt like it was a paint shaker. Anyone have any thoughts on what it is? I apologize if I should know this, but I am new to the site and new to owning a Porsche (6 months now). Thanks for any help.
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Old 12-29-2008, 10:19 PM   #2
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At the very least, go out and check your lug bolts. Also, you may have thrown some wheel weights - hit any potholes lately?

Can you isolate where it starts first?.... front, rear, etc.

good luck,

kj
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Old 12-30-2008, 04:27 AM   #3
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Quote:
Originally Posted by Boxster44
At the very least, go out and check your lug bolts. Also, you may have thrown some wheel weights - hit any potholes lately?

Can you isolate where it starts first?.... front, rear, etc.

good luck,

kj
The man is right about checking the lug nuts, but also check them for correct torque and not just to see if they are tight. Correct torque is imperative if you want a safe and wobble free ride. Ed
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Old 12-30-2008, 05:35 AM   #4
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Thanks. Lug nuts are tight and wheel weights are there. I didn't check the torque. The shake is so bad it is hard to tell if it front or rear, but I'd guess rear.
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Old 12-30-2008, 06:35 AM   #5
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Just to rule out your wheels and tires, get them road force balanced on a Hunter 9700 series machine. Many Discount Tire shops have them, but some don't so ask. With this machine, they have the ability to see the heaviest part of the wheel and the lightest part of the tire and match them to make the unit more balanced without weights.

If after you've done this the car is still shaking like crazy, a Porsche mechanic (dealership or indy) needs to inspect the car and drive it. He can then tell you if one of your wheel bearings is shot or not, which can cause bad vibration. My car had a horrible vibration problem that I could never fix with wheel balancing. I changed out the wheel bearings all the way around and it rides like a brand new car now.

These are the things that spin and cause vibration at speed. Another thing to check is your motor mounts, but frankly, they degrade over time and don't crap out on you overnight like what you are describing.

If it's a bearing, you should find a good indy shop to do the work for you. The dealership will rape you. The part is only $50 but the book rate for labor is something like 4-6 hours. An indy might just charge you actual time.
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Old 12-30-2008, 08:17 AM   #6
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Great tip. Thanks. I might just swap the wheel bearings as you suggested. I have new Sumi's coming this week and I'll see if they use the Hunter. I have heard from many people that the Hunter is the best way to balance. I'll advise later this week if that worked. Thanks to all. This is a really great site and everyone is extremely helpful.
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