Steering wheel shimmy in '02 Boxster

I’ve got an '02 Porsche Boxster (46K miles, manual trans., ABS) with a vibration in the steering wheel at 75-80 mph. It’s not a very bad vibration, but it’s there. Is it the alignment? A Porsche mechanic said there weren’t any problems with it (how could he pass up a problem if there was one?). Does something like this need to be done by a Porsche mechanic? Thx. Goatster.

My first guess would be the a wheel is out of balance at that speed. The tire store (I would guess you are at least on your first replacements) where you bought them should be able to do that easily.

If wheels are not bent, tires OK, balanced properly, and alignment is in specification. Then I am going to take a SWAG. Porsche may have aggressive negative camber settings for good (sporty) handling around corners. The problem may be you are doing mostly straight highway driving which I am guessing could wear the inside tread of the tire unevenly causing the vibration. Can you feel any uneven tread wear on the inside tread of the tire? Maybe someone with specific knowledge of the Boxster can be of more help, I am just guessing.

Lets check to see if it is the wheel/tyre or with the car. Have the tyres rotated (front to back is best for this). If the problem goes away or changes, you know it is a tyre or wheel problem. If it does not change, it is more likely an alignment or suspension issue.

Joseph when’s the last time you had a Porsche on the lift?? They’ve used staggered tire sizes front to back for years on their cars. A Boxster if I recall is a 205 front width 225 rear. You don’t rotate tires on a Porsche (or a BMW for that matter).

Goatster: There’s a few possibilities on this car. It is possible that you have a wear pattern on your tire that is causing the vibration. Take a look at the front tires-does the inside of either of the front tires look significantly more worn than the outside. If the answer is Yes I’m betting that’s your problem if the alignment is good. If they look evenly worn than you could have a slight bend in either wheel. Jack up the front and spin the wheels while holding a pen a few milimeters from the wheel. Can you see a wobble? If yes get the wheel straightened.

If there’s no wheel wobble and the tires are perfect, then you would need to check for wheel balance by taking it off the car and spinning it on a machine. if the wheel is OK then you need to check the alignment. If that’s OK there’s one possibility left I’ve seen-you may have a slight bend in a strut.

Good luck!

Dear Dave G.,
Thanks for the feedback. I can’t do such inspections at my residence. Can I take the car to a good alignment shop, or do you think it should be done by a Porsche mechanic (either independent or a dealership)?

Thanks to everyone who shared their insights on this. Goatster.

I think it would be wise to see an independent Porsche mechanic. I’m not a fan of dealers because you never know which tech is doing the work, and how much experience or patience he has. That and the prices are higher. When I worked for BMW it was all over the map from experts to someone who shouldn’t be working on anything more complicated than a lawn mower. A good Porsche race shop or independent who deals with the cars day in and day out gets to be familar with small quirks and and problems and can readily recognize them as well as spot things that are preventative maintenance. An alignment shop is qualified to do nothing other than align the car, and quite honestly most don’t even do that well as they don’t like dealing with camber adjustments and usually just set the toe.

On an unrelated note you need to watch the maintenance on this car like a hawk because things can get out of hand quickly. I recommend you keep the oil changed more often than Porsche suggests and make sure to use a quality synthetic that falls into spec for the engine. They’re hard on oil from what I’ve seen.

In conclusion find a good Porsche expert. There are two ways to do this: One is through local and national Porsche clubs who’s members will be familar with experts in your area. The second is to look through the mechanic files here on the Car Talk website and see if you can locate a Porsche specific mechanic. I don’t consider an “Import Shop” or a place that services 6 different makes of cars to be Porsche specific. It should be Porsche-only or Porsche and one other make possibly. Then go through the list I suggested earlier when you discuss option with this mechanic and describe the situation thoroughly. Good luck and let us know how it goes.