Shimmys at 75mph, what would it be

[OldMacTech]

Hadn't been on the interstate for awhile, this afternoon got it up to speed.
Around 70-75 when the steering wheel started shaking. Every few seconds it would smooth out but if I hit a little bump or accelerated it would wobble again.

Tires?
Wheels?
Ball joints?

Best guess.


Thanks.

Jb

[fatmike]

How old are the tires? When were they last balanced? Bent rim?

Could be lots of things, but I'd start there.


/

[Flavor 987S]

Yes, those are a good place to start. Tire pressures, too. Struts, bushings, control arms. Mileage? Year?

[Flavor 987S]

I was going to suggest "snow pack" but I see you live in Hotlanta. I crack myself up.

[Topless]

Originally Posted by OldMacTech

Hadn't been on the interstate for awhile, this afternoon got it up to speed.
Around 70-75 when the steering wheel started shaking. Every few seconds it would smooth out but if I hit a little bump or accelerated it would wobble again.

Tires?
Wheels?
Ball joints?

Best guess.


Thanks.

Jb

It's always a process of elimination. These questions should narrow the field a bit.
Model, mileage and yr of car?
Tire size, type and age?
Wheel size and Porsche OEM or aftermarket?
Any recent suspension or alignment work done?
Car been sitting for a long time without being driven?

[j.fro]

Got a buddy with another Boxster? Swap front wheels with him. I've got 2 sets of wheels, and when one set (usually the race tires) goes out of balance I get exactly what you describe.
FWIW, get lifetime balancing next time around, and have it done every 6 months.

[OldMacTech]

97 model. 78,000 miles.
Tires are good but not high quality-
1 wheel slightly curbed.
Always had a small shimmy around the same speed but noticeably worse today. ( does not get driven every day)
Was really wondering if since it seems to come and go after bumps if that was any indication of shocks or ball joints or more likely tires/wheels.

Thnx.

Jb

[Topless]

Yes. On a 97 with 78K miles it is tires/wheels/shocks/ball joints/alignment most likely and any of these things could potentially cause shimmy at speed. Swap wheels and it goes away? Tires or wheels are your problem. Doesn't go away? Shocks, alignment or ball joints are your problem.

Simply eliminate the possibilities one by one until your cause presents itself.

[runjmc2]

Small prior and larger after note driving....maybe tire flat spots. Mine is always very minor but increases if I don't drive it for 3 or so days and then gets back to normal after every day driving....

[HAUSIDMT]

Mine did the same, is there play in the front wheels when off the ground? I found out the tie-rods(outer and inner) were shot. $60 if I remember right for Moog replacements from Pelican, and $55 alignment. problem solved. Another tell tale for me was on acceleration if I let go of the wheel slightly it pulled one direction, and if on the brakes hard it pulled in the opposite direction. BUt with the wheel off the ground, if the play is side to side I believe it is tie-rods, and if the play is up down, could be control arms/other suspension components.

Disclaimer, I'm not a pro mechanic, but I've been steered in the right direction by some. And to date I've been able to fix the car on my own. Hope this info helps

[Mark_T]

It could be as simple as a wheel weight falling off.

[san rensho]

If you have access to another set of wheels, try it. If the problem goes away it's tires,wheels. If not, raise the front end, take the wheels off and shake everything down. Pull on all the control arms, tie rods, drop links, etc. Take a rubber mallet and hit all the ball joints and connections, if something is bad, you will hear it. If anything is loose, you found the problem.

[Kenny Boxster]

+1 On wheel and tires like the others said. That is usually the biggest cause. I had a problem with shimmy/vibration once and it was the front tires.

[Flavor 987S]

Originally Posted by OldMacTech

Hadn't been on the interstate for awhile, this afternoon got it up to speed.
Around 70-75 when the steering wheel started shaking. Every few seconds it would smooth out but if I hit a little bump or accelerated it would wobble again.

Tires?
Wheels?
Ball joints?

Best guess.


Thanks.

Jb

Originally Posted by OldMacTech

97 model. 78,000 miles.
Tires are good but not high quality-
1 wheel slightly curbed.
Always had a small shimmy around the same speed but noticeably worse today. ( does not get driven every day)
Was really wondering if since it seems to come and go after bumps if that was any indication of shocks or ball joints or more likely tires/wheels.
Thnx.

Jb

Here you go.