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Discussion Starter · #1 · (Edited)
Bent "Out of Round" Rim on 2001 Z06. Important Update for all 2001 Owners!!!!

Ok, as I am sure most of you have read my previous thread that I just had a new set of tires installed on my 2001 by a Goodyear dealer.

If not, please read it here so the story can be more clear.

http://www.z06vette.com/forums/showthread.php?s=&threadid=9593

Anyway, last week I took my car to the Chevrolet Dealership to have ALL 4 of my 2001 Z06 Rims and Tires checked on the Hunter GSP9700 Machine.

This machine can tell if your rims are bent or "Out of Round" even a fraction of an inch. Same for the tires.

When they tested my rims, they found that my Right Rear rim was Bent or "Out of Round." I was told that this was probably causing vibration or other adverse handling effects.

I told them that nothing had changed since I bought the car in the vibrations or handling and the car always seemed to ride rough and aggressive and I attributed that to the fact of the Z06's extremely firm and tight suspension.

The dealer stated that I might notice a difference with a new rim in place of the bent rim.

Well the dealer replaced my Rim "Under Warranty" with a new one. I was told that my original rim had a manufacturing defect and most likely came Bent or "Out of Round" from the factory.

As soon as the replacement was complete.......


WHAT A DIFFERENCE.

The car rides completely different now. Much much smoother while still retaining the aggressive and slot car feel. The hop, vibration and other things that I thought were normal for the Z06 suspension WERE NOT NORMAL, but due to the fact that I had a bent rim since I took delivery of the car.

Had Colony Tire (The Goodyear Installer) not told me that one of my rims was Bent or "Out of Round" I would have never thought to check this.

I would advise all Z06 owners who may be in the same position that I was in (With thinking that certain rough handling characteristics are normal for the Z06) have your rims checked with the Hunter DSP9700 Machine.

If I had one Bent or "Out of Round" forged 2001 Z06 rim FROM THE FACTORY, then you possibly could too!!!

Hope this helps......

JLA
 

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JLA,

Thanks for the info.
It's cool that the dealership replaced the wheel under warranty. It would've been easy for them to to get out of that one. Is your replacement wheel an '01 or '02?
 

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Wow very interesting info. I'll have to have mine checked even though I do not experience any symptoms:cheers:
 

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Discussion Starter · #4 ·
They replaced the Rim with a Forged 2001 Rim.

We were sure to check, double check and triple check this one.

JLA
 

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JLA -- Question for Ya

So just how far out of round was the rim? All rims will have some out of roundness, and there is a MAX spec that is usually specified.

When I had my 4 wheels balanced with tape weights, I noticed one of my rear wheels had a slight out of roundness to it -- I'd say no more than 1/16 inch.

I've had my Z upto 150 MPH and have never detected any vibration or ill effects. So maybe yours was way more than ~1/16 inch?? The guys who told you it was bad should have been able to give you the max out of roundness measurement.
 

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Discussion Starter · #6 ·
I do not have the exact spec, but the machine stated that the Rim needed to be replaced due to the fact that it exceeded the acceptable spec.

JLA
 

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The runout specifications are as follows:

With tire mounted on wheel - Lateral and radial..............0.050 in.
Just the wheel (tire not mounted) Lateral and radial.......0.030 in.

There is not a lot of allowable runout as you can see. And JLA's service tech has had sh&t together (at least for this problem) and took the time to read the service manual. Checking for excessive wheel runout is one of the most likely culprits behind wheel hop. This easily explains why some hop, and others don't.:cheers:
 

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my 2 cents...

I suppose it is possible that your wheel could have been manufactured wrong. Which should not happen with quality controls... but Murphy

A wheel will produce a noticable vibration when there is a 1st or 2nd harmonic "out-of-round" condition. Runout is more of a rough indicator and could pick up very small disturbances that whould not show vibration, but would indicate high runout.

1st harmonic would mean that the wheel centerline is offset from true center.

2nd harmonic would mean that the wheel is oval shaped.

If the wheel had a burr or something on the clamp when it was machined, that could cause a 1st harmonic.

It is also possible that a road-hazard (un-known to you) can cause a 1st or 2nd harmonic, but if it were the case you should see a noticable dent an inch or two wide on the rim flange.

I would double-check the front wheel from the same side.

:cheers:

Fish
 

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Discussion Starter · #9 ·
All of the rims were checked with the Hunter Machine.

No problems except the one they replaced.

There were no markings of any kind on any portion of the rim that would indicate any type of impact/road hazard damage.

JLA
 

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Oh great! I just had the same right rear wheel out of round. It was noticed by the tech at America's Tire and I had them send it out to be fixed.

$160 paid!

~John
 
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