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[Cloud9blue]

Still can't figure out why are my newly mounted R-S3 are out of balance after one track day from last week. Brand new Apex wheels, so no bend or anything, and all the wheel weights are still there. But the steering wheel would shake quite noticeably at speed above 80mph. The tires were balanced before the track day...

The only reason I can come up with is that the tires rotated on the wheels from the hard braking that I have done on the track. But I would be amazed that a street car with stock brakes is capable of such feat...

You guys have any clue?

Hmm, I have heard of that happening on a street car before, but obviously this Camaro is much more hard core than our stock setup so I doubt that's the case :-D
http://www.autoblog.com/2014/03/13/c...m-fixed-video/

My first guess is that the force variation within the sidewall has changed since they were first balanced though; which isn't too surprising since the tires are brand new and still need to "break in" over the course of a few hundred miles. I guarantee that if you threw them back on a road force balancer that they'd be out of balance in relation to the wheels:
http://www.gsp9700.com/technical/4202T/5THEO004.htm

You can spend all day reading about force variation, lateral runout, etc. on Hunter's site:
http://www.gsp9700.com/technical/index.htm

Either way, I'm willing to bet that's your problem. Find a good shop that can road force balance them, gather the road force figures they give you, and report back. Hopefully your assemblies can be force matched to an acceptable level so that you don't have to worry about swapping tires in order to reach low enough road force numbers. In my experience I've found that anything more than 9lbs of road force WILL cause some type of vibration/hop/shimmy/etc. at any given speed on these cars. Most other makes/models seem to not be as picky as our chassis tends to be.

[Cloud9blue]

Originally Posted by FCobra94

Hmm, I have heard of that happening on a street car before, but obviously this Camaro is much more hard core than our stock setup so I doubt that's the case :-D
http://www.autoblog.com/2014/03/13/c...m-fixed-video/

My first guess is that the force variation within the sidewall has changed since they were first balanced though; which isn't too surprising since the tires are brand new and still need to "break in" over the course of a few hundred miles. I guarantee that if you threw them back on a road force balancer that they'd be out of balance in relation to the wheels:
http://www.gsp9700.com/technical/4202T/5THEO004.htm

You can spend all day reading about force variation, lateral runout, etc. on Hunter's site:
http://www.gsp9700.com/technical/index.htm

Either way, I'm willing to bet that's your problem. Find a good shop that can road force balance them, gather the road force figures they give you, and report back. Hopefully your assemblies can be force matched to an acceptable level so that you don't have to worry about swapping tires in order to reach low enough road force numbers. In my experience I've found that anything more than 9lbs of road force WILL cause some type of vibration/hop/shimmy/etc. at any given speed on these cars. Most other makes/models seem to not be as picky as our chassis tends to be.

Thanks for the info, will drop by the local shop w/ roadforce balance during lunch.

[Cloud9blue]

Got them rebalanced. Much better than before, but still have a very slight vibration through the steering wheel if I go above 90mph. Must have been some flat spots from engaging the abs at the track.

The whole point of ABS is to NOT lock the brakes...doubt that is the issue. What were the road force numbers?