Vibration at 70mph
 

I just had new tire mounted and balanced on all corners. There is only a slight vibration when the car gets up to speeds above 70 mph. Could this be an allignment issue or is that just the way the Box's drive. :confused:

My first set of rubber on my boxster could never be properly balanced. I must have had the wheels balanced 6 times throughout the 18 months I had the car. I thought it must just be very sensitive steering and road feel. I even paid big money to have road-force balancing done on a Hunter 9700 machine (highly recommended, btw).

The offending tires were Kumho MX's, but I have heard others say that the same tire is fine on their car, so I think it was just the set I was sold.

Then I bought a cheap set of Sumitomos and wow, what a difference! Even on the cheapest tire I could find for the car, the ride was smooth as glass... no vibration in the wheel or from the rear end!

This taught me that if you can't road-force balance a new set of tires to smooth sailing at 80 mph, you need to ******************** about it from whomever sold you those tires and get a new set put on the car, and do it immediately.

Boxsters do give the driver lots of road feedback, but vibration from a tire can be eliminated by replacing the tire.

My .02 cents' worth anyway!

The previous set of tires I changed out would shake the steering wheel at 70. I bought the tires from tire rack and had them mounted and balanced by Lufteknic (local porsche shop in Richmond). The guy said the old tires were scalloped and that caused the shake. The new ones have 300 miles on them and have a slight vibration at 70. I have never driven another boxster so I have no room for comparison. Could a bent wheel cause this as well?

Any Idea how to deal with tire rack about new tire if that is the problem?

Anyone local to richmond that would want to get togther and check out my car's vibration?

Alignment?

Same Issue
 

VT,

I am going through the same problem.

At 15K, I went ahead and changed the rear tires--no change.

I had all wheels balanced--no change.

I was then told that I had "feathering" in the fronts and I could wait until 20K or so and I could have the fronts changed.

I am at 17K. I am enduring it for the next 3k and I hope to get that "smooth as glass" feel.

The rears that I got are Nittos. The fronts are Michelins (for now).

Laters!

Kai

BTW: I don't get the same vibration when the top is down--only when up or when I have the hardtop on. Is this the same for you?

Unless you already have the viabration issue before you got new tires, I am pretty sure it is the wheel balancing. I had a similar problem before on my ML 500 after balancing and rotation. Took it to a different shop and was told that the prior shop didnot scrap the old weights but balanced the tires by simply adding additional weights. I don't fully understood the logic. "Balanced" is "Balanced," right? But, I do not have the problem anymore. Probably taking your boxster back to the shop and have them rebalanced the wheels would solve your problem.

I have never used spacers but was told that these can cause viabrations.

There should not be a whisper of a vibration. I've taken mine to 112 mph without so much as a hint of a vibration.

It is not recommended that 2 different tires are used on the same vehicle. This can cause a harmonic vibration due to the 2 different tire's characteristics.

My tires on my '98 vibrated as well when I took it over 70 miles an hour.....I endured it til the tires wore out a few months back (I had Pirelli Rossos). I bought the cheapey Sumitomos like Randall has, and after getting the tires balanced, whala, no vibrating at all...Even after alignment also....And I've had it up to 118 and no problems. Sometimes it IS the tires........

Harmonic Vibration
 

As far as harmonic vibrations--is it something that I need to fix right away, or can I wait until the 3k?

FWIW, I think you could wait, but to be truthful, why wait?

If the tires are reducing your joy of ownership, get some new ones and chunk those old ones!

I sure wish I'd abandoned my first set waaaaay earlier, even if they had a lot of rubber left on them.

Of course, if you're financially strapped, you gotta wait. But if you have the cash, I'd say do it now instead of later.

Okay, this is what the mechanic said when I emailed him,

"Both of your rear wheels were bent, one was not bad, the other was more
noticeable (cant remember off hand which side was worse), they both balanced
out. Like we talked about, as you are driving... the tire is not round, it
takes the shape of the wheel, and over time becomes more pronounced, which
means they will require more balancing to keep the vibrations down. Also the
lower end tires seem to be more prone to this kind of sensation (road noise,
balance, flatspots, etc.), regardless of straight wheels or not. Slight
vibrations seem to develop at highway speeds. Another thing is with our
roads here, and hazards it is easy to bend wheels, driving through pot
holes, obstacles, etc. One last thing, with ambient temps as hot as they are
if cars sit on hot pavement all day in the blazing sun, or even for a few
days (such as an airport stay) you can develop flat spots, usually after a
few minutes of driving this becomes better. Hope this info helps, and see
you soon."

The vibration was present on the old tires and was very bad, and now on the new tires but is very slight. This makes me think that the problem it is not so much the tires but the wheels.

For clarifications is had Pirelli PZeros on before and switched to the Kumho all weathers. The wheels are 18" as well.

Randall - I would have no problem with changing the tires but I just had them put on. They have like 300 miles on them. :(

300 miles? Call Tire Rack Customer Care. They're usually very helpful in resolving problems.

Hi,

Were your tires Dynamically Balanced using a Hunter 97XX Machine? If not, they could be; a.) Mounted wrong (high side of wheel not matching low side of tire). b.) So out-of-round as to be off spec and not usable. Your Shop would then most likely balance them as close as they can, not necessarily eliminating any vibration. This is more frequent with less expensive tires and those purchased through tire discount centers...

Happy Motoring!... Jim'99

Not sure what machine it is but here is a picture of the one the shop uses. This shop specializes in porsches and sets up race cars and other specialty stuff. How can I find a place that has the Hunter 97XX machine?