eagle0001

Has anyone experienced shaking at high speeds? (i.e., between 120 - 140 mph) I am and it also makes the steering wheel shake as well. Any idea what would be the cause? Would repair be covered since my Z is still under warranty?

Thanks!

71Pantera

You might need a high prefromance tire balance. Try that.

Short-Throw

Are your wheels properly balanced?

Have you checked your wheel bearings?

MIGHTYM0USE

I've done it tons and still get a little nervous at those speeds!

Try bracing your elbow on the arm rest

Screamin Z

Hit anything hard recently? Had this problem on track. Took forever to diagnose it. Turned out to be a very sightly bent wheel.

eagle0001

Thanks for the replys.

Are Chevy service centers qualified to do high performance balancing? If not, what are my options in that case?

Thanks again!

Mookster

You might be experiencing the famous font end lift at those speeds which make the steering wheel dance.

eagle0001

No, although I did change my wheels. Can't say though if the shaking started thereafter. Could putting new wheels on possibly the culprit?

Bill Dearborn

There isn't anybody that can do that. The balance machines don't spin the wheel that fast. Read the instruction manual for the machine and you are certified to balance tires. It is that simple. Just need to be able to see and lift the wheel on and off the machine and have some coordination to put the weights on.

Does the vibration go away if you go over 140? I have lost wheel weights and had vibrations at one speed but none at a higher speed.

I doubt it is front end lift. My car is rock solid on the track surface at 154 with no sign of any lift.

A bent wheel or loose wheel bearing could cause vibrations that come and go. Get the car in the air and check the wheel bearings for play and if they are OK check to see how straight the wheels are by using a dial indicator to see if there is any lateral movement while they are rotating. Issue could be caused by a slightly out of round tire although that should show up at lower speeds.

Bill

eagle0001

Funny you asked if it goes away as speeds increase because it often does. I'll take the car into the shop and have them take a look. BTW, I had new Michelin PS2s installed at the same time I had the new wheels installed. Maybe that's the problem.

VetteVinnie

Check the alignment as well as the tire balance. Mine was a bit floaty above 140 until I redid the alignment, then it was solid up to ~160.

Bill Dearborn

Probably worth taking a very close look at the new wheels. You can get bent ones new right out of the box. One of my Speedlines I use for my street tires was scratched when a dealer was changing tires so they sent it out for repair. The repair shop refused to repair it because the wheel was bent. Until that point I had no idea it was bent. When we put it on the dealer's balance machine and spun it there was an almost infinitesimal wobble. So they bought me a new Speedline from House of Wheels which cost the same as the repair would have.

Bill

160KTS

I'd say tire balance is the most likely culprit. Get them road forced balanced and see if that fixes it. I doubt it would be floaty, because my Z still feels very solid at 140. A wheel bearing should show problems long before you reach those speeds.

capevettes

Find a shop with a Hunter Road Force Balancing machine. It actually simulates road conditions at speed and can detect faulty tires and wheels. A check on your alignment is also good advice.

383vett

Have the wheels rebalanced. When the tire/wheel combo is spinning, check the runout of the wheels using your eyes or a dial indicator. Visually check the roundness of the tires. Michelins are usually made to tight tolerances but things happen.

roscoe118

This may be a long shot, but what the heck. I recently put some CCW wheels on my C5, and immediately felt a slight vibration. One day a friend was following me and said he thought I had a bent rim on the driver's side, rear. When I pulled the wheel (don't know how I was going to tell if it was bent, but felt I had to do something...), I noticed that GM had installed retaining washers (may not be the correct name) at the base of 2 of the 5 lugs. I guess to hold the rotor in place when the caliper is removed. Anyway, when I compared the back side of the CCW wheel, with the stock wheel, I saw that the stock wheels had a recess that would encompass the washer when the wheel was installed. Since the CCW wheel did not have this, it was not sitting flush. I removed these 2 washers from each corner of the car, and wala, no more vibration.

It was very hard to notice at normal 0-65 speeds, but became much more pronounced at triple digits. Might be worth taking a look at yours, since you have after market wheels.

50 4Ever

Make sure the tires are above the wear bars all across the tires. I had this exact same problem, The tires needed to be replaced.

AzDave47

Mine is comfortably stable above 170, stock and 20K miles on the factory alignment. I'm not saying it couldn't be planted better, but it definitely still stable. I'll give more feedback on stability after I run the Mojave Magnum 1 1/2 mile in June where I should get to 183/4 although I may take the front air dam off before then, which should reduce front lift.

Ruf-Racer

I agree with AzDave47. I ran my 07 @ 160 mph (+) average speed for eighty miles & it was stable.
Stock alignment,dynamic balance & N fill on new tires. Shoreline Motor Sports in SoCal does all my tire & alignment work. Owner Paul is a former Michelin employee!

Cheers,

R

molon labe

1. check wheel balance
2. check alignment
3. bearings or bent wheel

fwiw, I've noticed this too on many performance vehicles at speeds above 120mph. seemingly minor issues with balance, alignment, aerodynamics, etc will generally become more pronounced at high speed.