Dope

Starting this spring my 99 C5 has started vibrating at around 70mph on the highway. It starts at 70mph and peaks around 75-80mph. It seems to vibrate the whole car but it's DEFINITELY vibrating the hell out of the steering wheel. If I take my hands off the wheel I can see it oscillating back and for very rapidly (almost a blur). Then it will randomly go away for a bit (10 secs, 30 secs, a minute)...and then come back. All at the same speed (cruise control set).

Having the car in a different gear doesn't change anything and neither does having the clutch in or not. Car drives nice and straight and maneuvers fine. Only 32k miles on the car and a couple thousand on the wheels and tires.

Bringing it in for a new alignment and re-balancing of the wheels just to knock out some likely culprits. Any thoughts behind the random nature that might point to something? I guess I'll check tierods and wheel bearings next...though I doubt it. I've found cars with bad tierods tend to wander a bit. Bad wheel bearings usually make noise. Out of balance tires or alignement problems usually cause a constant vibration problem. Never had a random vibration like this though.

Dope

Soul per4mance

steering Could be out of alignment, or tires could be rounded/feathered on outer/inner edges causing that vibration.

leadfoot4

Dope, sounds like you've already checked the usual culprits, so it might be time to look "outside the box". I'll start... since it appears to be a random thing, how about a brake caliper that's sticking once in a while, and causing the brake pad to "knock" against the rotor?

Got uid0

Usually caused by a flat spot on a tire.

Slotcar

I found this thread in a search. My vibration is not as random. For a lack of a better description, it is pulsing. It vibrates and fades away, vibrates and fades away all about 2 seconds apart. Now the odd part is that it goes away going around a slight bend in the highway. Obviously, the tires rotate at different rates when cornering so it might be a matching issue if there is any flat spotting (the car is on my lift for the winter). Curious to see what others experienced.

Dope

If yours goes away while turning, I'd think wheel bearing or tie rod.

Dope

Turbooo2u

I have the same problem with a 01' vert' I just picked up. The tires seems new. (Kuhmo Ecsta). I'm ready to get another set of tires. It's kinda ruining the "new car" experience.

k24556

wheel bearing. if the noise goes away just means the natural frequency of the system is different than the frequency of the vibration from the bad bearing. The clue is taking the load off in a turn unloads that bearing and it is not giving a high amplitude vibration.

1blkc4

maybe a bent rim or wheel bearing

wcsinx

For YOUR case, I can almost guarantee it's a worn tie-rod end. It goes away when you go around a bend because the steering load is pulling the slop out of the joint. My car does the same thing. I should get off my lazy azz and fix it at some point.

wcsinx

Typically wheel bearings "howl" when they start to go out. I've replaced many a wheel bearing, and I've never had one cause a silent vibration in a car.