Hi all,

This is my first post, I've used this site for awhile now and its a great resource. I hope to get familiar enough with this car to be able to provide some help in return one day. Anyways I'm finally stumped enough to have to write my own post beacuse I can't find any more suggestions in my searching.

I own a 2009 z51 base with about 26,000miles (it has npp and competition gray wheels otherwise LT1 stock). I finally did my first upgrade to switch to non-runflat Michilen Pilot Super Sports from stock tires. I got the tires from tire rack and installed them myself and roadforce balanced them myself (I work at an engineering company that has the equipment available to the engineers and have been trained to use these machines). I got out on the road and when I got to 75mph I started getting a vibration in the steering wheel. The vibration seems to come and go slightly, it is a very light vibration. Since then I have balanced the fronts 4 more times, got the roadforce as low as possible on the front tires (around 10), got an alignment, and had one of our professional mechanics roadforce balance the tires (with no change). I still get a vibration around 80mph. I am using the stock rims that the stock tires came off of and measured runout to be at most .005. None of the tires showed out of spec on the balancer as far as radial runout. I made sure to install by properly torquing the wheels by hand and then slowly up to 100ftlb. What else could be the issue?

-Ive seen the suggestion to remove the lock washers that hold the rotor on but only if you have aftermarket wheels, which i dont.
-turning the rim one lug at a time. This makes no sense to me, can anyone explain? The wheel and tire should be balanced and so should the hub why would this change anything?
-Moving the rims side to side. Again why would this change anything if the wheels were balance ofd the car?
-wheel bearing may be bad. Why wouldnt the vibration be present with the old tires?

Anybody got any other ideas or explinations? I am very particular about the way my cars ride and I am desperate to get the car back to where it rides smooth as silk as it did before the 1200$ tires I put on.
Sorry for the long post,
Brett

 

Welcome and congrats on your first post.

By reading your post, it appears that you have taken tires/wheels out of the equation as far as those causing your vibration.
Because it's the steering wheel shaking, that would indicate a front suspension issue.
With so few miles on the car, it shouldn't be anything major, but there are few things that it could be.
1) One of the wheel bearing starting to go bad.
2) Front wheel axle bent (very unlikely)
3) Steering gear (knuckles, rods, rack/pinion) have some play or loose.

Good Luck and report back if you find the culprit.

 

Following, I have the exact some issue. But it seems like it happened after I put on my new wheels/tires, I might just be crazy though.

 

I'd suspect wheel bearings first. Check for play both fronts and rears.
If you can find a GM dealer who has and knows how to use the chassis ears, it'll pinpoint the cause.

 

Same thing happened with me after switching to michelin ss tires. My opinion is that they are new tires and little bit more wobbly than the gys beacuse of the softer side walls. Beacuse it is intermittent it is a good sign of this. Some road surfaces cause this and once mine wore in a little after few thousand miles it got lot better.

 

I will take a look at the wheels bearings. I am unsure why changing only the tires would have any effect on the wheel bearings. I didn't have this issue before the tire change. Also it doesn't make any noise like a wheel bearing would and 26000 miles seems pretty low for a wheel bearing to go bad. I will take a look and report back.
Thanks,
Brett

 

If you didn't have any of these issues before the new tires, i have to believe the problem is in the balancing or you have a defective tire, i would contact Michelin. A bad tire would cause the problem.

 

I'm not familiar with the operations of the road force machines, but I suspect one of only two things. The machine is out of calibration, if that's possible, or the tire/tires are defective. Since you had no issues before the tire change, this seems to be the only conclusions, IMO

 

if there were no issues before this work, I say take it to the best shop in your area to have them balanced. There has been a rare issue at high speeds, over 100 mph, and Michelin has replaced them.

 

I don't know where you are located but if it were me, I would look for a forum member who would allow you to use a front wheel/tire in order to isolate which one is causing the problem. If you were near me, you could come over and we could put a wheel on in ten minutes and try it. This is a good reason to put info in your profile.

 

I agree with cclive.
Start eliminating possible issues.
I would remove the locking lug nuts if u have them.
How is your alignment?
Good luck

 

So I think I figured out what the issue was. I ended up re balancing the rears which makes no sense for the steering wheel vibration and I increased the pressure in the tires from around 28psi to 32psi cold. This pretty much took the vibration away. I noticed that when I was driving before that when the tires got warm it seemed to get better. In response to some of your suggestions, I got an alignment, I tried balancing on two different machines just to be sure, we looked at the runout on the tire and they were within specifications. To return a tire to michelin they require a mechanic to fill out a form stating what the issue with the tire was. Since everything says the tires are fine I don't think that was going to be a possibility. Either way I am going to keep driving and see if I experience any further issues. I appreciate all the assistance.

 

I had put aftermarket wheels on my car in Jan 2016, had them balanced, installed and drove it for about 200 miles and I to had a vibration in the steering wheel.
I would suggest getting an alignment and seeing if the stabilizer ends are wore out. Yes mine happened to be and I have a 2009 with Z51 package, once this one done I have no known issues and the vibration is no longer there.

 

It's one of the new tires. Sometimes you get a bad one.

 

So even after adjusting the pressure I still am not happy. I agree with you all, even though its measuring fine I contacted tire rack about it. They immediately sent me a new tire with really no question once I explained the issue. It will be here tomorrow, so we will see. Tire Rack customer service really surprised me, I expected to have to fight for it. Highly recommend them if anyone needs tires.

 

Another frustrating update. I got the new tire from tire rack, ive installed it now on both sides with no change in vibration. I also took off both front wheels and wire brushed all mounting surfaces. Both tires have under 10 on road force. I took the tinnerman nuts off all the lug studs just to be sure. I am more or less out of reasonable ideas. Does anyone have any other suggestions? Otherwise I might drop it off at a dealer and see what they can find.
Thanks guys

 

There might be an issue with the front suspension that you simply did not feel with the GY runflats, but now you CAN feel it with the Michelins due to the softer sidewall and/or tread difference. Obviously, just guessing here. Good luck!

 

You stated that one of the tires was possible bad and had it replaced; which tire was it and how did you determine it was defective?
I could see a shock that is not working as it should 100% magnifying the out of balance issue, because you stated that the vibration was a on and off sensation. But still, the tire with a balance problem is initiating that theory.
If you have access to a high speed balancer, just for the heck of it, re-balance with that machine.

 

I couldnt tell which side it was so I put it on the side with higher road force number. Then when that didnt fix it I put the tire that was on that side to the other side. I dont have a high speed balancer, only access to the regular tire balancer. I was thinking that it could be other suspension components or the tire hitting the same frequency as the spring? I'm not sure if that's possible.

 

your new wheels could be out of round which would cause your problem. ask me how I know.