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Cup 2 problems or the car or the Z07 suspension?

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Old 07-16-2018, 10:55 PM
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Amirns
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Default Cup 2 problems or the car or the Z07 suspension?

I have the cup2 on my car and I got the car a week ago and daily it (im changing the tires soon), but it gets very sketchy at times when I hit small holes on the road or any part of the road thats not smooth the car starts pulling and here in LA we dont have the best highways so at 80mph when I hit a imperfection on the road the wheel pulls and it very scary. Anyone have the same experience? Is it the cup2's or maybe the z07 suspension? Any tips would be appreciated
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Old 07-16-2018, 11:23 PM
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Originally Posted by Amirns View Post
I have the cup2 on my car and I got the car a week ago and daily it (im changing the tires soon), but it gets very sketchy at times when I hit small holes on the road or any part of the road thats not smooth the car starts pulling and here in LA we dont have the best highways so at 80mph when I hit a imperfection on the road the wheel pulls and it very scary. Anyone have the same experience? Is it the cup2's or maybe the z07 suspension? Any tips would be appreciated
Hard to tell from your description. Are you talking about the car following grooves in the road or pavement seams where two different layers of pavement come together? If that is what you are experiencing the wheel alignment needs to be checked. A little bit of toe in can reduce the wandering and make the car much more stable on the road. Corvettes have done that since the C5 came out. Before the C5 they weren't as sensitive to pavement condition. However, with the correct wheel alignment they won't do it. The tires may contribute a little to the issue but the Cup2s aren't as stiff as the early C5 run flats and shouldn't affect the steering that much. The suspension has nothing to do with it.

Oh, by the way compared to some other states California roads are smooth as glass. Wait till you hit 5 potholes big enough to swallow your wheels in a matter of seconds.

Bill

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Old 07-16-2018, 11:35 PM
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Originally Posted by Bill Dearborn View Post
Hard to tell from your description. Are you talking about the car following grooves in the road or pavement seams where two different layers of pavement come together? If that is what you are experiencing the wheel alignment needs to be checked. A little bit of toe in can reduce the wandering and make the car much more stable on the road. Corvettes have done that since the C5 came out. Before the C5 they weren't as sensitive to pavement condition. However, with the correct wheel alignment they won't do it. The tires may contribute a little to the issue but the Cup2s aren't as stiff as the early C5 run flats and shouldn't affect the steering that much. The suspension has nothing to do with it.

Oh, by the way compared to some other states California roads are smooth as glass. Wait till you hit 5 potholes big enough to swallow your wheels in a matter of seconds.

Bill

Its not just the grooves or the pavement seams, every time the road gets a little bumpy it does it, it doesn't matter if im doing 90 or 40 but obviously its more at high speeds. Even on smooth roads it does it sometimes. When driving in the backroads with sport suspension it gets very scary when ever I hit a very very small bump and it pulls much more in turns and I try to push the as much as I can. I will have the alignment checked tomorrow. Are there any other things that you think I should try?

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Old 07-16-2018, 11:47 PM
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Agree with Bill. Alignment.

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Old 07-17-2018, 12:00 AM
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Originally Posted by Rookieracer View Post
Agree with Bill. Alignment.
Im gonna have it checked out tomorrow and will let you guys know
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Old 07-17-2018, 12:11 AM
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Originally Posted by Amirns View Post
Im gonna have it checked out tomorrow and will let you guys know
Be sure to ask if they have the special tool to monitor rear caster. Most dealerships don’t have it.

Also you may ask them to set it to the DSC sport recommended alignment settings.
http://www.dscsport.com/wp-content/u...ent-sheets.pdf
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Old 07-17-2018, 12:25 AM
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Yeah it's definitely the alignment. I have a Z07 as well and I recently had an alignment done because I didn't want my tires wearing out on the insides but after the alignment the tech was adamant that there is NO rear caster adjustment on this car. I argued with him for about 5 minutes before I just decided to drop it and go elsewhere. After their alignment I am confident that the tires won't wear on the inside now, but every bump I hit the rear end gets real loose right after. It is an odd feeling but I only felt it after they messed with the alignment and didn't touch the rear caster.
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Old 07-17-2018, 04:33 AM
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Originally Posted by Rookieracer View Post

Be sure to ask if they have the special tool to monitor rear caster. Most dealerships don’t have it.

Also you may ask them to set it to the DSC sport recommended alignment settings.
http://www.dscsport.com/wp-content/u...ent-sheets.pdf
Appreciate the link. I wont be taking in to the dealer, I'll take it to a shop that knows what they're doing. If I dont have the dsc module will the specs still be fine with the factory computer?

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Old 07-17-2018, 06:22 AM
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The 3 things that helped my Z07 drive 100 times better on the street, one, get you car aligned by someone who knows how to do a new Corvette, mine was off from the factory, and the alignment was covered under warranty. Two, get rid of the cup tires if your just driving on the street. Three, get the magnetic suspension update, it made my car night and day difference on the roads I drive on.
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Old 07-17-2018, 06:25 AM
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Originally Posted by hcvone View Post
The 3 things that helped my Z07 drive 100 times better on the street, one, get you car aligned by someone who knows how to do a new Corvette, mine was off from the factory, and the alignment was covered under warranty. Two, get rid of the cup tires if your just driving on the street. Three, get the magnetic suspension update, it made my car night and day difference on the roads I drive on.
I plan on getting either the continentals or the super sport ez not sure yet, what specs did you use for the alignment? By magnetic ride suspension upgrade are you referring to the dsc module?
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Old 07-17-2018, 06:29 AM
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Originally Posted by Amirns View Post
I plan on getting either the continentals or the super sport ez not sure yet, what specs did you use for the alignment? By magnetic ride suspension upgrade are you referring to the dsc module?
Had Continentals on my 16' have pilot super sports non run flats on my 17', had them do street alignment at my chevy dealership, they have a corvette only person. The magnetic ride update is done by the dealership and costs 350, best money I ever spent at a dealership
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Old 07-17-2018, 06:42 AM
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Originally Posted by hcvone View Post
Had Continentals on my 16' have pilot super sports non run flats on my 17', had them do street alignment at my chevy dealership, they have a corvette only person. The magnetic ride update is done by the dealership and costs 350, best money I ever spent at a dealership
Wow I didn't know they had an upgrade, my car was at the dealer yesterday, I guess im going back in a couple of hours for the update. Unrelated question: which tire did you prefer for driving on the street with the z07 package?
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Old 07-17-2018, 07:26 AM
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It's the wide tires. They like to track the imperfections in the roads. I've always had this issue and don't believe there is much you can do unless you go smaller up front.
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Old 07-17-2018, 08:06 AM
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Originally Posted by Amirns View Post
Wow I didn't know they had an upgrade, my car was at the dealer yesterday, I guess im going back in a couple of hours for the update. Unrelated question: which tire did you prefer for driving on the street with the z07 package?
I like the Conti's but they picked up a lot of loose stones where I drive, so I went with the non run flat pilot super sports, I change wheels and exhausts on everything I buy, it's a sickness
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Old 07-17-2018, 08:51 AM
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Originally Posted by saleen556 View Post
It's the wide tires. They like to track the imperfections in the roads. I've always had this issue and don't believe there is much you can do unless you go smaller up front.
I have had cars before with 285 in the front and haven't had any problems where I drive. After this getting info on this thread I think that its definitely the alignment and I feel like the cup 2's dont help either
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Old 07-17-2018, 08:55 AM
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Originally Posted by hcvone View Post
I like the Conti's but they picked up a lot of loose stones where I drive, so I went with the non run flat pilot super sports, I change wheels and exhausts on everything I buy, it's a sickness
You are not alone, but hey its a good problem to have
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Old 07-17-2018, 10:27 AM
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How much psi are you running?

As others have said, get the alignment set correctly including the all important rear caster.

Then get the DSC controller.

Bish
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Old 07-17-2018, 11:26 AM
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Alignment.

I LOVE my Sport Cup 2s. Got 16k out of the first set and now have 4k into the second set. Amazing sticky tire. My car is stable at speed and not at all twitchy like you speak of. I did get a proper STREET 4 wheel alignment at one of the larger Corvette dealers here in Houston right after I got the car. Tires wear very evenly.
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Old 07-17-2018, 02:10 PM
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Originally Posted by JAYNO20 View Post
Yeah it's definitely the alignment. I have a Z07 as well and I recently had an alignment done because I didn't want my tires wearing out on the insides but after the alignment the tech was adamant that there is NO rear caster adjustment on this car. I argued with him for about 5 minutes before I just decided to drop it and go elsewhere. After their alignment I am confident that the tires won't wear on the inside now, but every bump I hit the rear end gets real loose right after. It is an odd feeling but I only felt it after they messed with the alignment and didn't touch the rear caster.
The easiest way to win one of those arguments with the shop is to have them check the alignment instructions that are in the GM service manuals that are on every mechanic's computer. The FSM tells them the specification for rear caster and tells them which tools to use and how to use them. There is also a TSB on how to do the track alignment. The way I found out about the TSB is because a dealer service writer told me about it and provided me with a print out.

One of the things that leads to the problem is I suspect the GM Service Group tells them they don't have to worry about rear caster with standard alignments. The spec is 0.0 degrees +/-0.8 per side with no cross caster spec. From my experience playing with my alignment almost every of rear camber will fall into that rear caster tolerance so you can have +0.8 on the driver's side and -0.8 on the passenger side and that is OK per the GM spec. Since all recommended GM rear camber settings get the caster within that spec why bother spending $1K to purchase the tools to measure it. The shop manager (not the service manager) who purchases all of the tools at the dealership where I get my car serviced told me he wasn't spending $1K for tools to service one car (mine). I didn't like his decision but he didn't BS me he told me they were not going to do it.
The mechanic that works on my car says he will do the rear caster adjustments if I bring my tools in.
Bill

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Old 07-17-2018, 06:00 PM
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Originally Posted by Bill Dearborn View Post
The easiest way to win one of those arguments with the shop is to have them check the alignment instructions that are in the GM service manuals that are on every mechanic's computer. The FSM tells them the specification for rear caster and tells them which tools to use and how to use them. There is also a TSB on how to do the track alignment. The way I found out about the TSB is because a dealer service writer told me about it and provided me with a print out.

One of the things that leads to the problem is I suspect the GM Service Group tells them they don't have to worry about rear caster with standard alignments. The spec is 0.0 degrees +/-0.8 per side with no cross caster spec. From my experience playing with my alignment almost every of rear camber will fall into that rear caster tolerance so you can have +0.8 on the driver's side and -0.8 on the passenger side and that is OK per the GM spec. Since all recommended GM rear camber settings get the caster within that spec why bother spending $1K to purchase the tools to measure it. The shop manager (not the service manager) who purchases all of the tools at the dealership where I get my car serviced told me he wasn't spending $1K for tools to service one car (mine). I didn't like his decision but he didn't BS me he told me they were not going to do it.
The mechanic that works on my car says he will do the rear caster adjustments if I bring my tools in.
Bill
When I read your report, I'm a bit surprised.
What are those only for workshops, Corvette Handler without tools?
In the US, the parent company of the Corvette

We do a lot of alignments on the C7 Corvettes.
I always say to my boys:
On the Corvette C7, the rear axle / caster alignment is the most important.

Cölestin
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