Amirns

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

Bill Dearborn

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

Amirns

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?

Rookieracer

Amirns

Im gonna have it checked out tomorrow and will let you guys know

Rookieracer

HorsePowerObsessed

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.

Amirns

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?

hcvone

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.

Amirns

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?

hcvone

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

Amirns

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?

saleen556

hcvone

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

Amirns

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

Amirns

You are not alone, but hey its a good problem to have

thebishman

jcthorne

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.

Bill Dearborn

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

Lasco001

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