lexrally

Hello Forum

On the highway on a 9 hour trip recently. About 5 hours into the trip, the car starts to
vibrate. It is a low rumbling vibration felt thruout the car. This vibration starts at speeds
greater than 40 MPH when foot is on the gas. While this happens, it goes away almost completely when I let go of the gas. If I am cruising or accelrating, the vibration occurs. It gets progressively worse as the speed increases. It lasted for about an hour, then completely went away for the remainder of the drive to our destination. On the way
back home, same thing happened. Car running smooth for a few hours. Then vibration starts.
Vibration stops. Starts up again. It is very noticeable.

I ran thru the forum searching for an answer. Apparantly it could be one of several things
1. Wheel Balance (but why does it go away and come back)? Tires are Michelins
Cross Terrains, I checked air pressure etc, and there is no shimmying in
felt in the steering wheel when driving. They have ~20K miles on them.
2. TRAC control (I turned off TRAC using button while this
was happening on the return trip, and vibration did not go away)
3. Suspension components: I recently had the left front driveshaft replaced 3K miles ago.
4. Rotors. But on acceleration? The front rotors are slightly, when braking they
do shimmy a little bit, but hardly that noticable, nothing like the vibration
that happens on the highway while cruising/accelerating.

The biggest mystery is why it goes away completely and then starts up again?
When I say completely, I mean there is absolutely no vibration whatsoever. When it start up
again, it is very noticable. It is not felt thru the steering wheel more than it is felt thru the floor and cabin of the car.

So not sure what could be the cause. I will start with a wheel balance. But I don't
know if that will fix this issue because it is intermittent, a wheel balance would
be a consistent shake wouldn't it?

mshumack

You might have a CV joint starting to fail. Are any of the CV boots torn? Is there CV grease thrown/slung around the inside of the wheel and/or CV shafts?

lexrally

The left front axle was replaced recently due to a torn cv boot. The cv joint itself was ok, just the boot sprung a leak and all the grease came out. The right shaft was not replaced yet. But the right shafts boots are not torn as there is no evidence of any grease having leaked.

BTW this is an '02 with 108K miles. The front left cv axle was replaced around 3K miles ago.

mshumack

Start with a balance and have the tires rotated too. If you are starting to get tire separation that may explain why the vibration is dependent on temperature (i.e. as the tires heat up they respond differently). Also make sure the technician looks over the tires very closely. Lastly, pay attention to whether or not the vibration moves (i.e. with the tire rotation).

Xtom73G

My 2000 RX AWD suddenly had a highway shimmy. Right front wheel had thrown its weights, 4 onces out of ballance. Tire shop fix, no charge, smooth now. If CV is going, you might feel a slight shudder or vibration on acceleration from a stop, or in a turn at low speed.

lexrally

Took it to the tire shop today where I bought the tires. Of course they took a test drive and were not able to duplicate the problem. They checked the wheel balance and tires they were good. They checked the front end all was good. Checked alignment, good. They said the left drive shaft was still under warranty, so they will replace it once they receive the replacement part. They didn't charge me anything too, quite unbelievable, it is Atlantic Tire in Raleigh. I asked if we could take the cv axle boot off to see if the joint really was damaged and causing the issue, but they said you probably wouldn't be able to tell by looking at it.

mshumack

Why are they replacing the left CV shaft ("once they receive the part")? Do they suspect that there is a problem with it? It's a lot of work to replace it - especially since they say they can't duplicate the problem.
Also, if the tires were rotated, that might help narrow down whether or not its a tire issue (there could be an internal tire problem not visible through inspection). So pay attention to if the vibration moves after the tire rotation.
Good luck

fastnoypi

very good points, one Mercedes i had a while back had a vibration problem we were trying to track down for months. It wasn't till we rotated tires, the vibration moved. One tech finally discovered the cause was from the tire installer. The tire installer had used ALOT of tire lube solution,( i'm assuming soap and water) to mount the new tires, enough to cause a small puddle inside the tire. At reaching certain speeds, the "puddle" would cause the tire to go off balance.
I hope the original poster will find the cause.