farne230

Tadge:

I just purchased my 2016 CO6 ZO7 C7.Rpkg. I have 400 miles on it and every time I turn at low speeds the tires rub, jump ect... "Michelin Pilot Sport Cup 2 tires" is this still the engineering flaw called "Ackerman Effect"? I am not a racer or run the vehicle on the track, but I don't like this feeling every time I leave my parking area or turn onto open streets, what can I do? I never had this with my C6 2008 ZO6.
Thanks,
Bob

farne230

I just returned from my Chevrolet dealer and here is what I found out: GM #14-03-10-001B Tire Hop/Tire Chatter During Tight Turns at Parking Lot Speeds (Nov. 18, 2015)

2014-2016 Corvettes (Z51 & Zo6): "While a customer may find the noise troubling and /or annoying, the car is operating as designed." Ackermann steering geometry worsens with C7 corvettes due to sticky tires and build up forces as they turn on the different arcs until eventually one or both tires slip. My experience with just 400 miles on tires and suspension it seams to worsen. I never had this problem with my 2008 ZO6.

I also took my car in for its 500 check and find out why the synchronize button control driver and passenger side AC/Heater will not turn off. Had to leave it overnight.

RC000E

Ackerman effect isn't going to go away as long as cars have 4 wheels and a steering system that internally links the front tires together as one. So, in the 2017...yes...still there. Cars with wide, grippy tires and some element of scrub radius are going to "hop" at low speeds and sharp cornering.

FortMorganAl

I though if we could go to the moon we could solve any engineering "problem".

Ackerman geometry solves one problem but not another. It's physics or, more correctly a geometry issue that becomes more evident with wide sticky tires. Until we get a President who writes an Executive Order changing pi to 1.00 you will just have to live with it or buy cheaper less sticky tires.

farne230

One solution might have worked, when purchasing the ZO7 package with these sticky wide no tread tires, these tires would have come with the Old ZO6 tires or with sport Cub tires (more tread, better for driving and last a little longer). If someone or the less then 1% who purchase these cars prefers the soft no tread Sport Cup 2 tires then select it as an option. I know this does not change the "Ackerman Effect." I believe the 2008 ZO6 (C6) also was plagued with shorter wheel width at front verses back and I didn't notice at low speeds and sharp turning the tires skipping and jumping. I think these Supper Sport tires were soft but had more tread and may not be as soft as the Sport Cup2's. Just my 2-cents.

Your right though if you order a ZO6 with ZO7 package expect this problem (Ackerman Effect); it has been around for at least two generations of ZO6's, an engineering decision made to improve turning radius (per GM).

-Eric-

I don't see it as a problem. It's a tradeoff in the interest of performance. Weighing these tradeoffs is part of the car buying process. Some people see 2 seats as a tradeoff. Those people might be happier with a CTS-V than a Z06/Z07 If this is really annoying you there might be a better fit for you than this car.

jsmortman

I am a brand new Corvette Owner and equally new to this forum, so excuse me if I am not saying things up to speed yet.
Everything I am reading, like it or not, this issue is not my own and not something wrong with my car. The only question I have, does it cause any damage to the car or just makes it feels like the tires are falling off.
I have been shying away from this happening, should I not?
Thank you

-Eric-

It could be a little hard on some of your suspension components if you are gassing it hard enough to cause hopping while making a tight turn. However slight scrubbing and a little noise should not be an issue for anything other than tire wear. I wouldn't worry too much about it. It's mostly just annoying. I don't blame you if you avoid making excessively tight turns so that you don't have to hear the noise. I do the same.

farne230

I would guess that this problem with the design will cause some additional unwanted wear on tires which are the very soft. I suspect the edges will wear first and soon we will need replacements and in my case it will not be MI Cup2's. I am curious if other tires will skip and jump on sharp turns at slow speeds?

jvp

Um. Yes? The ZR1 was the first car with the Michelin Pilot Sport 2s, and they chattered all over the place when doing very tight turns. The PS Cups did the same, as do the new Pilot Super Sports. Any wide R-compound tire I ever put on my car also did the same.

It's not a big deal. At all.

BT ZR1

100%

mustclime

this might help.....

farne230

Appreciate the video. I have 800 miles on the z now and it is beginning to become lease obvious.
Bob

n8dogg

I wanted a race car, so I bought a race car, but I don't want it to drive like a race car.

ELEFUNTMAN

I went from an 07 Z06, to an 11 Z07. The 07 was smooth, no jumping around. It had Bridgestone's. When I bought the 11 I really thought there was something wrong, being very similar cars, the 11 has the Michelin's, was worried at first, till I read up on it. Car drives great, still hopps around at tight turns, however I stopped worrying.

JerryU

FWIW, it's NOT and engineering flaw! The patent on the need for Ackerman steering geometry was issued in ~1815 for horse draw carriages!
There is a simple solution I have used since I got my Z51 C7 in October 2013- when it's cold I don't turn the wheel anywhere near full lock when backing out of the garage in the morning, I make "K" turns! Since my C7 Z51 was an early build and I had not experienced anything close with my Z51 C6 I did some investigation of why it happens. Knew all about Ackerman but some facts indicated that was NOT the whole story!

Unlike some comments posted it's not IMO sticky wide tires! It did not happen to any extent with the same width tires I had on my Z51 C6!
GM also states it is worse in the rain with low traction! I have validated that thru observation.

The KEY to the following statement is folks who switched to the same size and aspect ratio All-Season tires state it goes away!
It's the tires! Particularly with your tire construction (not the tread compound) that is similar to a race car. The stiff side wall design provides excellent response and very low "slip angle."
Higher slip angles cause the tread to "squirm" (for lack of a better technical term) and then "full Ackerman geometry is not needed."

There are some negatives to using "full Ackerman geometry" so manufactures don't use it for for any car, they rely of some tire slip angle.

Probably enough quick info to digest, here is a PDF with lots of pics and graphic info! http://netwelding.com/Wheel_Chatter.pdf

Bottom Line: When it's below 45 F where the tires are stiffer and the tire tread "less sticky"- don't turn near full lock, keep it >1/2 turn less and make "K" turns! For those folks who think that is a PIA, when you're doing it just remember the great lateral "g's" you'll achieve in the summer!
In fact now that it's warm I use full lock in the morning! Still get a slight amount but don't feel like the front end is coming apart!

04train

My Wife's CTS Coupe does this as well, so maybe not an alternative

Flyboy22

What's really so bad about it? As long as you know it's fine, who cares.

The only reason I can fathom being bothered by this is the thought that something might be wrong. And it isn't. It's hardly jarring or emotionally scarring.

JerryU

But with the lower profile Z51 and the even more race car type construction and tread compound on a Z06, at 35 to 40 F it feels like the front end is coming apart! I know GM says "it does no hard" (they also say don't drive when the tires are cold) but I prefer making "K" turns to feeling that "hopping" as GM calls it!
Again no big deal.