sasilverbullet

I'm having that dreaded wheel shimmy (very slight though) at around 61ish. And then at over 80 or so I can feel the vibration getting worse. I've got the original Pirelli P-zero's on, adjusted to the 29/36 psi.

Are our cars prone to this? Any words of wisdom?

Steve Wilwerding

Generally, "wheel shimmy" is caused by unbalanced tires. There can be more serious problems, but almost always having your tires rebalanced will cure your problem.

How many miles are on your tires?

sasilverbullet

14K, and they supposedly were just balanced by the Porsche dealer, that's what worries me!

Steve Wilwerding

It's also possible that one of your tires is out of round. Instead of taking it to a Porsche dealer, try a reputable tire shop. They can pop the tires off and see if they're balanced, which shouldn't take more than a few minutes and shouldn't cost much (if anything). I'm still leaning towards this being a tire problem.

Generally if something were mechanically wrong (bad bearing, worn suspension components, etc.), it would manifest itself all the time rather than at one certain speed. In 99% of the cases I've heard of people having shimmy problems, it was caused by the the wheels or tires being out of balance.

sasilverbullet

Will do...I called the Porsche dealer and they gave me the name of the tire place that did the work. I'll bring it back to them to and get them rebalanced...

Thanks!

JeffES

Be sure to check that they are using the Hunter (that's a brand name) Road Force Anaylizer - a rather pricey tool that is recommended, by name, in several Porsche Service publications. It's far, far better than a simple "balance", and can often find the source of such irritating "squggles".
J

horo

Just last weekend, I went to the local Craven Tire & Auto, and asked about rebalancing. I also was having a shimmy at about 62 mph. I was quoted "Road Force" balancing at $24 and change per wheel. I had them do it. I was pleased to see the counter guy write "hand tighten lug nuts" on the slip without being prompted. I also asked that they visually inspect each tire for obvious defects before performing the pricey balancing. I have the Continentals that came on my 2002 S when I bought it used. I left the car, and when they called they said that two of the tires (RF and LR, I believe) came up "overweight" which basically meant they couldn't be balanced. However, they had road-tested up to 60 (as fast as they will go on local roads), and said it was much smoother. They also said the treads on all the tires ($18K miles) were fine, and if the vibration problem wasn't an issue for me, there was no reason to replace the tires. I note that they don't carry the brand, so they weren't going to get a quick sale, but I think they were being honest anyway I asked about putting the two questionable tires on the rear, but they said that the F and R are different widths, which I hadn't noticed.

Anyway, I picked the car up and it's 100% improved. No shimmmy at all, and I've had it up to around 80. The only bad part is I got used to getting a little "warning" as I passed through the low 60s, and I've found myself going a lot faster than I thought

So, go for the Road Force balance. I feel like I got my money's worth

sasilverbullet

I just returned from a awesome tire shop here in town. All four tires were not balanced correctly. After re-balancing them, almost all the vibration is gone, it's very acceptable now.

JeffES

Good to hear! The very lightweight and rigid aluminum alloy suspension parts on the Boxster can transmit any tire problems/issues - it's very important to have the tires/wheels properly set up.
Enjoy the ride,
J

Wachuko

There is also another post on Pirellis having quality problems... I think it was in the 996 TT forum... found to be the culprit in vibrations over 60mph