stockc5Z06

the handling has went to crap in certain situations. Most notably around a fairly large corner ie. ramp to get onto highway. Accelerating thru a corner till i am starting to go to fast, instead of hitting the brake, I would let off the gas. When I do that the front end dives in and makes the rear seem to want to come around.
This has made cornering not as fun as it used to be.
03 Z06, 500 miles on Continental extreme contact dw, stock wheels, 255/40 front, 295/35 rear .
Had an alignment done by corvette shop. He said alignment was neutral for tire life???
What could cause this? There was absolutely no problem with old, cracked, worn to wear strip firestone firehawk wideoval.
thanks for the help

WannaC5Z

When you lift off the gas the weight transfers to the front. When cornering fast while doing this it can cause your rear to get loose. On the track you can control this with light throttle, but if you're talking about on a highway on-ramp or exit ramp, I wouldn't try that or you may eat a siderail. It doesn't sound like a tire issue to me, it sounds more like a shock issue. The dampening of your shocks may be wearing out. How many miles? Could it be that your new tires are stickier and therefore the shocks are being engaged more?

PLRX

Neutral alignment?

Would that means zero camber, zero toe?

The Z06's factory's specs are a bit into the negative camber.

This is the rrason is alwaus a wise idea to align a Corvette with a Corvette experienced shop.

Moto One

It's your alignment... Stock it -.75 front and rear. With and 1/8 toe in rear. Also Im glad to hear that the front end tucks in. I'm going to the 255 front after having run the 275 for the past two years. (Conti Extremes DWs).

Mark

stockc5Z06

93,000 miles i'm assuming stock shocks, i was planning on some C6 Z06 shocks. Looks like sooner than later.

stockc5Z06

I took it to a corvette shop. He said he can do track alignment or street alignment for better tire wear??? I had street alignment done.

stockc5Z06

I have always been a car guy and making this post because the car handles so much different from just doing a tire swap.
I have looked under car mostly at sway bar and endlinks, everything looks ok and tight.
Any other condition the car drives the same. IDK

Socko

I agree with Moto One, my guess is also alignment. dw's are pretty terrible but still much better then 5+ year old tires. If the alignment was reciently putzed with i am sure that is what the issue is.

Toe wears tires for sure, but you need a tiny bit of rear toe in to keep the rear end in line, i run 1/16" in, 1/16-1/8 is accepted as a good value. The camber ratio front to rear is important too. -2f/-1r moves the car toward oversteer vs -1f/-1r which is relatively more understeer. Any achievable camber stock, without shims, will not wear your tires any appreciable amount, your alignment guy is wrong if he says it will. Feel free to play camber all you like. Caster should generally just be maxed. It will likely be uneven but that doesn't really matter. As caster is just relative camber it is fine to play with it if you wish.

If you are quickly letting off the gas with the car loaded, if its anywhere close to the limit, the *** will be happy to come around. All corvettes have more then enough power to loose traction at any point if you try to power through anything. If you let off the gas you are braking with only the rear tires, which is imminant doom at anything close to fully loaded. So don't do that!

Socko

Thinking about this, you need a significant amount of rear camber to keep the rear end in line as well. I wonder if he pulled out rear camber to get you a flatter contact patch, and maybe better percieved tire wear due to more straight line grip, which resulted in not enough camber to hold any corner loads in the rear. My first alignment had that issue cause my rear camber was too low to just get enough total rear grip. I had like -1.2/-.5 then changed to -1.7/-1. With -1 in the rear it made a world of difference in total rear grip.

PLRX

Do the C5 Z06 alignment

What alignment did you have before all this changed?

I found this chart in the forum

His93C4

That is exactly the feeling I have. I just put the Continentals on 2 weeks ago. I am giving them back and going back to Bridgestones. The rearend is not planted. It wiggles and wags and just wallows. It sucks bad. When I do a slalom with it, it wiggles about 2-3 times before it takes a set. I hate these tires. They instill no confidence in the car. I got them at Discount Tire and they come with a ride guarantee. I believe that Continental has a 60 day ride guarantee.

philadd

What tire pressure are you guys running the in the rear? When I had the Continentals I did not experience any of the issues described here, but I did run a lower pressure than normal in the rear tires.

JETninja

I've been running the Pfadt Street/Track w/street tires setup since end of 2011, love it. Tire wear is great, and turn in fantastic. Big change from the stock settings....

grantv

The Z is aligned pretty much for track use. If you chose "door number 2" (street alignment) that's the problem mostly I'd think. It's a Z, give it a Z alignment. Will your tires wear faster? Yes. Will it handle like it's supposed to? Yes.

PLRX

stockc5Z06

thanks for the help guys, I will get factory alignment and report back

Moto One

The one thing that know one asked is just how low are you in the rear. If the car is slammed then you could also be bottoming out, and that is a recipe for loose rear end...

I know that the Conti DW's feel a bit soft on turn-in but there traction in a corner is right up there with PS2s, and their ride and noise factor is far better then the Mich's.

With the correct alignment and tire pressures (34 f and 32 rear has worked for me) they wear evenly with out cupping, and my over all milage (with a number of track days) is right at 21k with the rears just now at about 1/32 from center wear bars in the rear. Fronts still have 4/32 across the tread.

Mark

dbgoodwin

Very interesting thread. I have the DW's in 275/295 and couldn't be happier with them. Around turns it takes A LOT of throttle to make the back start to kick out. In a straight line the rear tires are glued to the pavement. The fronts do push wide a little bit compared to the goodyears, but a couple extra pounds of pressure helped a bit. Overall much more confidence inspiring than the f1's I took off.

stockc5Z06

Car is stock ride height and running same pressure (34 f and 32 r)

Black 03 Z06

Watching this one with interest.

Taking a WAG alignment is the problem. I agree the tires could do it but not the first place I would look to solve the handling issue.