steering vibration - 986 Forum - The Community for Porsche Boxster & Cayman Owners

D.L. · 03-27-2005, 05:37 PM

Hello. I am new to this site, but love it so far. I have a 98 boxster and noticed a vibration in the steering wheel at about 77 MPH and up. Smooth as glass at slower speeds though. I had the wheels re-balanced and the vibration is still there! Any suggestions to help troubleshoot!????!?!

This is my first roadster, so at first I thought it was normal due to the shorter wheel base and harsh roads out here in Seattle, WA. But, I'm not sure if it's normal or not. Any help or suggestions appreciated!!! thanks in advance.

David

phrankandbeanz · 03-27-2005, 06:37 PM

i have a 2004 boxster and I have the same problem, the balance is perfect and I cant seem to figure out what it is

Brucelee · 03-27-2005, 07:30 PM

If you have a vibration only at a certain speed, it is almost certainly a wheel balance issue.

Wheel balancing is an art and a science. Depending on the technology employed, a wheel can be "in balance" and not be so at certain RPM.

Suggest you find another wheel balance technician.

Good luck.

Pilot2519j · 03-28-2005, 05:54 AM

Also make sure to check the alloys for any dents. Don't take it as a guarantee when a shop has done the wheel alignment, if it does not feel right bring back until is done properly. If not tell them to return the money you paid for services not done.
Did they perform high speed balancing of the tires?

Brucelee · 03-28-2005, 06:14 AM

Yes, in fact, to get the wheels perfectly on a Box, the shop should do both dynamic and statis balance and deal with any discrep. between the two. Also, as pointed out above, if the basic wheel has issues, this will make the balance even all the more challegning.

RandallNeighbour · 03-28-2005, 12:56 PM

What BruceLee is referring to, if I am not mistaken, is two different kinds of wheel balancing.

One is done "normally" by spinning the tire by the center of the rim the way you're probably used to seeing it done.

The other way, which is not that uncommon, is to balance the tire under a load or what he referred to as "dynamically".

I have heard that some Discount Tire stores have both kinds. That's the place you want to take your Boxster.

Another option is to call a few rim shops that specialize in high performance tires and rims... they have balancing equipment that goes up to and beyond 100 miles per hour.

I am told that wheel balancing problems go away after 90 mph or more. So, one very cheap fix for your problem is to drive faster!

Of course, one could become dangerous at high speeds or incur speeding tickets, so that may not be the best idea!

If my explanation requires correction and I'm not right on my descriptions, please do post it here so that I can learn more as well. I've NEVER been pleased with the balancing of my wheels since I bought my boxster last year... had them balanced three times and just decided to live with it.

Brucelee · 03-28-2005, 04:30 PM

The downside to the feel that a box has is that it IS sensative. Hence, any little balance issue is felt whereas in some other cars, it would not be noticed.

The good with the bad!

D.L. · 03-28-2005, 10:27 PM

You guys are fantastic with information! I believe the vehicle was taken to a local Firestone and they did the basic wheel balance, and not a "dynamic" wheel balance. I've heard they are also called "high speed" wheel balancing and they are done at my local Porsche dealer, but they charge an arm and a leg! Not to sound harsh, but I'm glad I'm not the only one that is experiencing this problem.

If there are any other suggestions or personal experiences, I would love to hear them. I LOVE the car, but the vibration is a bit of a pain.

D

Shortbus · 03-29-2005, 08:51 AM

I have a similar problem but mine seems to stop once the tires start warming up a bit. Could it be the tires being balanced in summer, i.e. warm weather then driven in winter where it's cold?

YellowJacket · 03-29-2005, 11:08 AM

Quote:

Originally Posted by Shortbus

I have a similar problem but mine seems to stop once the tires start warming up a bit. Could it be the tires being balanced in summer, i.e. warm weather then driven in winter where it's cold?

I have your problem. I was wondering if I had some bad bushings or something and if the vibration was coming from them instead of the wheels and that the rubber had to warm up to operating temperature.

But yeah, on cold days, I get crazy front-end shimmy from about 70+, and then 3-4 miles into my drive, it just instantaneously stops.

Shortbus · 03-29-2005, 11:23 AM

On top of that I noticed when it starts vibrating, If I turn a bit, like let's say switch a lane or even two, the vibration will usually wear off too. Pretty weird.... At least it seems it's not as uncommon as I expected it to be :dance: :chicken:

Torino · 04-28-2005, 10:04 PM

I'm almost a 100% certain that all the problems you are relating to (vibration) is caused through the twomass-flywheel.
I had a Audi S3 (not sold in the US) with very similiar problems. Needless to say, it took Audi 3 times to solve the problem (after denying it first...). So that was a 3 time clutch out-clutch in job.
After the last replacement it finally felt like it should have been...

ntmatter · 04-28-2005, 10:11 PM

Another option, if you want a really perfect wheel and tire setup, is to get your tires shaved. Tires are not, as a general rule, perfectly round. When mounted on your wheel they'll be slightly out of true, so even on new and perfectly balanced tires you'll get a little vibration.

You can have your tires shaved, which is basically having them turned on a lathe after the tire is mounted to the wheel. This results in a perfectly round outer tire diameter, though it'll get messed up if you ever have the tire off the rim. I did this for a set of race tires once to get the tread depth right and it was like driving around on silk.

The other downside is that you're scraping off good tire until all everything is evened out, so this will significantly reduce tire life.

socratic · 04-28-2005, 10:20 PM

2001 Boxster here. The previous owner put on some new Kumhos before selling and I presumed they were balanced. But the car started vibrating at about 80mph.

I took it to a shop with a Hunter 9700 wheel balancer that does a "road-force balance"; that is, it applies a 1000 lb force to simulate the car on the road.

Let me describe the results this way: If the original state was 0% and a glass-smooth balance was 100%, then the job they did was like 80%. I still feel a bit of a vibration. I am now hearing through this thread and other places that Porsches are finicky. I will bring it back to them and ask them to check it again since it's only been a few days since I did the balance.

The place I went to also had a new machine (their Hunter 9700 was old they said). It is a machine called a "John Bean" and it looks "higher tech" using lasers to measure out of round wheels. But it did not have "road-force" and so I asked them to use the 9700. Maybe I'll ask them to use the John Bean as a '2nd opinion".

socratic · 04-30-2005, 06:57 AM

An update.

Went back to the tire shop. They double-checked both fronts with the Hunter 9700 and they both came out fine according to the Hunter.

One of the techs said that previously, the Hunter told him that one of the fronts was, and I can't remember the exact term, but it had a high spot. At that time, they did me a nice favor and popped off the tire and rotated it so that the high spot of the tire would match the lowest part of the rim. It still wasn't perfect but it was the best they could do.

Since the shop also had a new John Bean balancer, I asked them to use it to give me a "2nd opinion" wiith it. The John Bean did not have the "road-force" device. But it did have some sort of laser camera, 3 in fact, that helps determine if the wheel/tire is not "true" in any way. The John Bean confirmed that the balance was pretty much dead on, but with its cameras, it was able to tell the Tech that it was 0.25 off (I can't remember the unit, e.g. whether it was millimeters, inches, etc.)

The bottom line is that the tires are perfectly balanced but one of them is slightly not perfectly round. When asked if I should replace the tire, they said no, since there is some wear on the tires, a new one would have more tread and the steering would pull to one side. They recommended that since I don't do much high speed driving, that I suffer until the tires are worn and then get 2 new ones.

The next step, though I am not optimistic, is going to be a wheel alignment by a good shop. I've been told that alignments should be done every few years anyways. It's going to cost the equivalant of about $80 USD and I'm prepared to spend that to keep the car in good shape.

Brucelee · 04-30-2005, 07:54 AM

"It's going to cost the equivalant of about $80 USD and I'm prepared to spend that to keep the car in good shape."

Yes you should have an alignment and actually $80 is a very good price. Most shops charge well over $100 for exotics.

Make sure they have the right equipment and know how to do this job.

Good luck. :dance:

limoncello · 04-30-2005, 08:10 AM

Random thought - 77 mph. I feel slight but noticable transition when the spoiler comes up. The feel of the car changes a little, as does the sound pattern (very slightly but there). Shouldn't feel anything thru the steering wheel though.
Rear alignment at a local shop - $69.95. The local PCA folks use him and say he's very good. At that price (and given the rear tire cost) I think I'll put it on a as a regular interval item.