Strange wobble

[nsx4fun]

I have a very mild and strange vibration at freeway speeds. There is a small vibration in the steering wheel when cruising on the freeway that comes and goes. It takes around a mile to cycle through from it's worst (which is still very minor) to absolutely none and back to it's worst. It does this on perfectly smooth asphalt. I have ruled out road surface causes. The one mile cycle changes if there is a long bend in the road. So it seems to be linked to something like tire rotational differences side to side and something goes from in sync to out of sync over the course of a 1/2mile approximately.

Any ideas? Any tire balance/suspension/drivetrain experts out there that can offer a good technical explanation.

BTW, I don't notice anything at 100+ speeds, it seems to happen (or is only noticable) just in the range of 55 to 70.

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Fritz

 

[Edo]

That is VERY indicative of an unbalanced tire.
Go get it balanced at a good shop and see what happens. If that doesnt fix it, you might have some other problems, but my guess is balance. Almost 99.99% sure of it.

 

[nsx4fun]

I have had the tires balanced, actually a premium balancing where they start rotate the tire on the rim first to minimize the weights required to balance. And if it was just balancing, why would it come & go so repeatably over distances of a mile. Something is going in & out of sync for this kind of vibration. Can you provide a good technical explanation of what I am experiencing?

Fritz

 

[Edo]

I was assuming that the speed of your car was ever so slowly changing 1-2mph over the course of a mile or so. You can't drive a car exactly at an even speed as far as I know.
Tire imbalance problems sometimes seem to come and go because of this slow fluctuation in speed. Most imbalance problems are most apparent at 55-70mph. Above that they shake too fast for it to feel like a wobbly feel.

Also it could be that your wheel is a bit bent? Have the tire dealer check to see how much runout there is on your wheel.

Otherwise I can only think that you have a much more serious suspension/Alignment problem.

Check the alignment next.

 

[Larry Bastanza]

NSX4Fun,

I recommend you have the wheels balanced ON THE CAR. I have heard of this before. If each wheel is very slightly off, let's say from rotor balance, they will not show up on the high speed balancer separately, but when they spin together and each are a little off, the SUM may make the wobble at certain speeds.

A bent rim will wobble at ALL speeds but change frequency.

HTH,
LarryB

 

[bobyang]

I've had a similar problem in another car of mine. Turns out some water or some other fluid had leaked INTO the tire. The guy unmounted my tire, drained it, let it dry, and remounted the tire on the wheel. Voila! problem fixed.

 

[nsx4fun]

I like the suggestion of balancing the wheels on the car. I think I'll see if I can find a place that can do that (starting my search at Comptech & Niello Acura). As for holding a constant speed, Flat & level the cruise control works very well and my speedo is dead on as verified by a GPS receiver. Alignment problems? The car was aligned when I had the new rims and tires put on (which is when the problem began). And those mile long tests watching the vibration come & go was done with very little hand contact on the steering wheel (most of it no hands driving on I5). The car rolls straight and true.

Thanks for all the replies.