Coilovers/? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

clb0099 · 05-21-2009, 08:25 PM

I had 19" brand new wheels mounted and balanced as well as installed on my 1997 Porsche boxster. After going on the highway and hitting 70 mph and above the steering wheel shakes violently. It use to shake with the stock wheels but was very little even not noticable . My question is I already bought coilovers which are not installed. I also bought brand new front wheel bearings . The question is a two fold one. First what the hell could it be making the steering wheel to shake like this... bearing? ball joint? tie rod? How would I test to see what it is? The second part of the question is how much it cost me to install coilovers exclude a car alignment?

Boxtaboy · 05-21-2009, 08:42 PM

You do realize that Porsche did not even offer 18 inch wheels as an option in 97? They beefed up the suspension in 98 to allow for 18s. Running 19s on a 97 model year car is really not recommended, but I'm not sure if that is the reason you are experiencing shaking at speed.

ekam · 05-21-2009, 08:44 PM

I say it's a wheel balancing job done poorly... that or you're using a set of cheap/replica wheels.

edevlin · 05-22-2009, 02:21 AM

Ditto on the possibility of poor balancing. Find a shop that uses a Hunter road force balancing machine and see if that helps. I bought my carrara lightweight aftermarket 18 inch rims with tires mounted, supposedly balanced. I also got vibration until I took them in and got them road force balanced.

Ed

clb0099 · 05-22-2009, 04:07 AM

Ekam... i got to disagree with you on the cheap comment. They are TechArt wheels almost 3k.... Also they put on my Porsche so not sure if that is the case. It happened on my stock 17s so i am not sure that it's a wheel problem at all instead I thing it's a tie rod or maybe a ball joint anyway of testing these myself to let me know.

j.fro · 05-22-2009, 04:56 AM

To check the front suspension components, jack up the front end and give each wheel a good shake. There should be no play at all. With both front wheels in the air and the steering wheel unlocked (key on but car NOT running), you should be able to move the front wheels through the entire turning arc. There should be a little resistance, and it should be uniform through the arc.
Check the tie rod ends to be sure that the lock nuts are tight.
Because you've experienced the problem with both sets of wheels, my guess is going to be alignment. Does the car pull to one side or the other at highway speeds? If the toe is very different from one side to the other it could cause this problem...and going to a larger diameter wheel may be exacerbating it. Did you have heavy wear on the inside edge of only one of your old tires?