Vibration at 65-70mph

I drive a 2003 Jetta Wagon. This car normally has nice handling in
the 75-80mph range.

This week, I took my car down a logging road. As I got further down
the road, I was committed to maintaining my speed of 30-35mph due to
soft sand. While this road was pretty smooth, it did bottom out a
number of times as the center of the road peaked, forcing me to
change my track. Other than plowing through a bit of sand, no
problems. When I finally escaped the logging road, my drive home was
rather uneventful, but I noticed a slight vibration at 65-70mph.
Later that day, on another trip, the vibration felt more dramatic.

The tires on the car were in pretty bad shape, good tread, but showing
signs of age and bad alignment. That said, no problems driving at
80-85mph for a 10 hour stretch.

So now, I have a pretty bad vibration at 65-70mph that feels like it
is coming from the front end. The vibration is not limited to the
steering wheel, it feels like the whole car is vibrating.

I feel like my problem is related to my trip down the logging road. I
feel I have damaged tires or knocked something out of alignment
despite the fact that I experienced no high speed impacts or jolting
blows.

Here's what I have done so far:

1) Thinking I have some accumulated mud and sand, I pressure washed
the undercarriage as best I could.

2) I went to mechanic #1. Based on my description and his inspection
for damage, he felt it was a wheel balance problem. Suggesting that
one or more front tires might have shed a weight. We aligned the
front tires. Same problem, no improvement.

3) I went to mechanic #2. Mechanic #2 pulled front wheels and
together we looked for any obvious signs of damage. None found, the
mechanic felt that this was a tire balance problem and mechanic #1
had improperly balanced the tires. Mechanic #2, put the front tires
on the balancer and found they were perfectly balanced. Problem
continues.

4) Now, I put my own logic to work. I understood that a badly damaged
tire could be balanced without revealing a problem. So, I purchased
two new Bridgestone tires for the front, with tire balancing, from
mechanic #3. I also had the mechanic look for any signs of damage
that could lead to a high-speed vibration. He didn't find any
problems with mechanicals, but showed concern about the rear tires.
He said the rear tires looked good, but were cupped and out-of-round.
He doubted that bad rear tires could have caused that much vibration
on a front-wheel drive car.

This condition has all the signs of out-of-balance front wheels/
tires. What else could provide those symptoms. Right now, my next
plan is to replace rear tires, have them balanced, and have the car
aligned.

I didn't mention earlier, but the car is tracking straight with no
problems until I start getting the vibration at 65-70mph. It doesn't
feel like an alignment problem, but I am running out of ideas.

Thinking about drive train, suspension, and wheels - nothing I can
think of mimics the out-of-balance feel.

Any ideas?

Damron wrote:

> I didn't mention earlier, but the car is tracking straight with no
> problems until I start getting the vibration at 65-70mph. It doesn't
> feel like an alignment problem, but I am running out of ideas.
>
> Thinking about drive train, suspension, and wheels - nothing I can
> think of mimics the out-of-balance feel.
>
> Any ideas?


It sounds to me like the wheels. You may have slightly warped a wheel when
the car bottomed out. The only easy way to check that is to get ahold of
two front wheels and swap yours out to see if the problem goes away. I
know you said they looked at the wheels, but it only takes a very slight
dent/bend/warp to cause problems at 65-70 mph.

I've actually a very similar problem on an Audi and it turned out to be one
of the brakes. That was a very unusual circumstance... In Colorado, they
use this ridiculous magnesium chromite to salt the roads because they're
worried about salt harming the environment somehow. I can't really see how
magnesium chromite could be any better than salt, because it eats right
through metal if you let it sit long enough. Anyway, some of this crap got
into one of my brakes and just stayed there for about a year, and it
finally caused the caliper to fail to release completely. So the caliper
was very slightly rubbing up against the disk as I drove, but it wasn't
noticeable until I was going about 55-65 mph. I could imagine sand in a
brake caliper causing a similar issue, but I still think it's more likely a
slightly deformed wheel.