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I got my '06 M6 about 3 weeks ago. I made it through the recomended 500 mile break-in. Now I have 700 miles on it. I decided to try a hard, not crazy, start off a traffic light. Massive wheel hop. Went to another road and tried again, same thing. My heart sank. Today I checked the tire pressure and lowered them all to 32 PSI. Went out and tried an even harder launch with wheel hop so bad that the bottoming out bumpers were hitting. I can't believe it. How could GM put out this type of car with a problem like this ? Is this a common problem or do I have a possible suspension problem ?
 

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What's in your wallet?
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Common problem for all of us, whether an A4 or M6. Some will recommend the Harrop diff cover or drag bags. I personally used the Energy Suspension rear cradle and diff bushings. It helped a great deal.
 

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DAE HAN MIN GOOK!!!
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what? 500 miles isn't magically gonna change the fact you have an IRS...
 

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yes,i totally agree that the wheelhop sucks.i have an 04' m6 and it wheelhops mostly at the dragstrip.i've done alot of research on this and from what i've heard,the bmr airbags work best.the reason for the hop is the IRS suspension,and the soft springs.i almost thought of getting rid of it for this reason,but every car has its downfalls.fbodies,the 10 bolt rear is fairly weak....mach 1's i've heard horror stories on trannies....imports suck....,etc.the goat is really awesome other than this,especially since you've got the torque monster ls2.get some airbags and watch the tires melt and the SEG expand.....:burnout: :burnout: :burnout: :burnout: :burnout:
 

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gtoldman said:
I got my '06 M6 about 3 weeks ago. I made it through the recomended 500 mile break-in. Now I have 700 miles on it. I decided to try a hard, not crazy, start off a traffic light. Massive wheel hop. Went to another road and tried again, same thing. My heart sank. Today I checked the tire pressure and lowered them all to 32 PSI. Went out and tried an even harder launch with wheel hop so bad that the bottoming out bumpers were hitting. I can't believe it. How could GM put out this type of car with a problem like this ? Is this a common problem or do I have a possible suspension problem ?
The cause of the wheel hop is harmonic. It is a small vibration that reverberates and grows until it explodes as wheel hop. The causes and solutions are well known and documented although that never slows down internet myths. Here are the causes and the solutions in order of priority.

1. Soft OEM Cross Member bushings that hold the rear 'cradle' in place with large Torque to Yield bolts (replace these bolts with new GM bolts) in front of each wheel well. Replace the OE rubber bushes with Pedders EP1145 progressive urethane bushes to eliminate wheel hop and maintain your OEM ride quality.

2. Springs rates that are tuned for comfort and not hard launches. The rear springs in your GTO are Mini Bloc springs that can fully compress or nest without touching the coils. Under serve load, hard standing starts, the spring literally lets the car squat down to the bump stop. Replace the OEM springs with a Pedders progressive mini bloc. We have springs from to raise lower or maintain your OEM ride height.

3. Shocks that are tuned for comfort and not hard launches. Pedders GSR shocks are valved to be progressive and work as part of a complete solution in your GTO The harder and faster your compress the shock the greater the resistance the shock will provide. Launch hard and the shock becomes 'hard' to handle the load.

4. The differential is mounted to a rubber block and flexes under load. This prevents the car from realising the potential of the IRS. For OEM HP range vehicles use Pedders EP1157. This urethane insert will settle down the Differential. Unlike some other products on the market it does not require and destructive weld drilling to install. The other option is a Harrop cover which complete replaces the OEM mount is is the best solution for hard use as it more than doubles the oil capacity of the differential.

5. The two piece drive shaft can create vibration under load that is made worse by poor cradle alignment. There are three parts to this solution. First have your rear cradle aligned by fixture at a qualified shop. Until two months ago aside from a Pedders shop I doubt anyone knew this was required. Most larger Pontiac dealer bought the tool from GM but were not told what to do with it and have one sitting in a box. This should be done when you align your vehicle as routine maintenance. The front cradle should be aligned the same way followed by a four wheel alignment which does not impact wheel hop. Finally for High HP vehicles a one piece drive shaft with a safety loop is in order.

You can turn your Goat into an erector set and play around with what amount to Band Aids or you can fix it the right way. Can you use parts from high quality vendors other than Pedders -- certainly. But when your vehicle still has wheel hop or some other suspension related problem who is responsible to resolve it? Pedders is a single source, single solution, single phone call that works.

You can find a list of Pedders Dealers on our website. They know your GTO inside and out.
 

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Discussion Starter #6
500 mile magic???

jonlee said:
what? 500 miles isn't magically gonna change the fact you have an IRS...
500 miles was the break-in period. I didn't want to get to rough with it until after that. I didn't hop the wheels as I left the dealer. Get it now ?
 

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Discussion Starter #7
Thought IRS was a good thing, as in Corvette.

blackws6 said:
yes,i totally agree that the wheelhop sucks.i have an 04' m6 and it wheelhops mostly at the dragstrip.i've done alot of research on this and from what i've heard,the bmr airbags work best.the reason for the hop is the IRS suspension,and the soft springs.i almost thought of getting rid of it for this reason,but every car has its downfalls.fbodies,the 10 bolt rear is fairly weak....mach 1's i've heard horror stories on trannies....imports suck....,etc.the goat is really awesome other than this,especially since you've got the torque monster ls2.get some airbags and watch the tires melt and the SEG expand.....:burnout: :burnout: :burnout: :burnout: :burnout:
I thought that wheel hop was a solid axle leaf spring problem. My brother had a stock IRS Corvette that could smoke the tires without even thinking hop. I tried to do my homework on this car before I bought it. I read reviews, test drive reports, and some forums like this. Never read anything about wheel hop. When I used the search feature of this website for 'wheel hop' it got the bad news I wish I had gotten before I bought the car. But you are right, the car is awsome and no car is perfect.
 

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gtoldman said:
I thought that wheel hop was a solid axle leaf spring problem. My brother had a stock IRS Corvette that could smoke the tires without even thinking hop. I tried to do my homework on this car before I bought it. I read reviews, test drive reports, and some forums like this. Never read anything about wheel hop. When I used the search feature of this website for 'wheel hop' it got the bad news I wish I had gotten before I bought the car. But you are right, the car is awsome and no car is perfect.
Pedderised = Perfect!
 

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I had major wheelhop and got DR's hoping that would help and it helped a little bit.I get wheel hop sometimes and sometimes i dont.
 

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Bx Goat said:
I've got my Pedders trackII system in my bedroom waiting for the spring. What I did do before the suspension upgrades is upgrade to a 1 piece DS from extreme performance. My wheel hop is almost all gone. I'm attributing this to either the 1 piece DS or the fact that my rear tires have almost no tread left. Don't let this thing get you down brother. If you go to a Porsche 911 forum you will see that they have wheel hop issues as well. To make you feel even better, they pay over twice as much to have a car that hops.

=)
The drive shaft alters the harmonic balance of the drive line. There is one less source of vibration: the joint that has been eliminated. When you install your Track II system have the front and rear cradles aligned and a four wheel alignment done at the same time. You can cord your new tires in 1st 2nd or 3rd :gears:
 

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wat it fis mofo
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looks like the airbags are a great bargain
 

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Wheel hop is not limited to the GTO. I had it on a hot lap with a Mustang gt and a Caddie CTsV. the cadi was so bad, I thought the tranny was going to pop

Mike
dms
 

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Capital City GTO's
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How much is the install cost of a GTO Street II package?
 

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Growing up is an option
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looks like the airbags are a great bargain
well i don't know about that. on the first launch after i put my drag bags and diff insert in i wheel hopped so bad i snapped my drive shaft in two. on the bright side, i have a one piece difftech drive shaft now :). Pedder springs and x-member bushes are in the mail now as well as shocks and control arm bushes. my car was great stock and i had some pretty good runs at the track with it. the thing is as you add power the need for better suspension starts to come in. it's part of the "pay to play".
 

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Clean is good...
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Moon Rider
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cheap fix is to buy a set of airbags from BMR and that will take care of the wheel hop I run 10psi in my bags and haven't had wheel hop since.
 

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Agree its all about harmonics, but for what ever reason some cars (like mine) has a natural frequency that aggravates it more that others. Mine had pretty bad wheel hop 100% stock. Then I went to town on the rear suspension. Harrop, X-member bushings, springs, shocks, and a sway bar for good measure... Feels much more planted and effective (still stock power at the time) but, still had wheel hop although not as violent.

Biggest change, honestly was the new wheels and tires. Also the new wheels weight is different (I think they are a little less than stock). Now I had a noticeable different reaction, duhh I have 275's now. And I don't hop as much (I guess my car's natural frequency had changed). Then I put more power in it. I have had several moments of actual smooth wheel spin and a little hopping at times... Just my experiences.
 
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