Worried, just bought 2015 Z06, when I turn the wheel too much to right or left it sounds and feels like a jeep in four wheel drive. The front tires rubs or skips and make horrible noise. Thump Thump Thump just like a jeep would do when it's in 4 wheel drive and you turn wheel too much.
is this normal or do I need to bring it to the shop n get it checked. Thanks

 

 

Get rid of the runflats

 

You have nothing to worry about it normal. There is a very technical explanation as to why it occurs but most people aren’t interested they just want to know it’s normal.

 

RTFM

Tire Chatter/Hop

When driving at slow speeds and in
very tight turns, the vehicle may
have tire chatter/hop. This condition
is normal and the vehicle does not
require service.

 

This issue is explained in the owner manual, called the Akerman effect.

 

Thank you for your immediate response. It helped

 

I bought my 2015 Corvette stingray a year and a half ago with 7404 miles on it and very clean Carfax. When I took it out of storage in April 2018, I experienced the clunking noise in the front of the car when I would back it out of the driveway or take a tight turn. I thought this to be the Ackerman Effect.This past April when I took it out of storage, I immediately dumped the run flats and had Michelin Super Pilot A/S tires put on the car at an excellent tire shop. The front noise sounds continued. The tire shop inspected the front suspension and told me to take the car to Chevrolet dealer because of loose front end issues. The dealer replaced the two stabilizer bar links (they were loose) and a new front left arm control (bad bushings). They also did a multi -point inspection on the vehicle. Luckily, I have an extended warranty. The car has 13,550 miles on it now at the completion of this work.
Now there is no noise at all even when I back out of the driveway or take a turn.

The big question is, how does a car with a clean Carfax and 7404 miles on it have all kinds of suspension issues?

 

It's NOT the run flats nor simply Ackerman steering geometry, it's the high performance Michelin tires race car type very low slip angles!

Yep if you buy lower performance tires with higher slip angles with the same Ackerman geometry (which doesn't change) and it goes away! If you like the high lateral "g' force you can achieve when warm best JSUT to understand what it is! This is a PDF I researched when my early September 2013 built Z51 was so bad on the first cold day with the SAME tires width I had with my C6 wanted to to find out why! Check it out: http://netwelding.com/Wheel_Chatter.pdf

This is one pic of many in the PDF:


PS: It's also NOT the "sticky' tires some say is the cause. Gets worse when the tires are cold and less "sticky" and worse when wet! The PDF defines why! There is also a simple solution I have used for 5 years! When below about 45 F, when I back out of my garage instead of using full lock to go down the driveway I turn the wheel less and make a "K" turn! When warm, like now, a full lock turn does not cause the issue. Usually get these questions when It's cold NOT when it's warm out!

 

CarFax doesn't check the mechanical condition of the vehicle. In fact they don't even have all the service or repair information.

Just for the record: I live in south FL, so "cold" really isn't a thing here - and the OEM tires made the chatter noise regardless of temps. I immediately noticed the noise when pulling in or backing out of my driveway. Read up on the problem and realized it was normal. Now I recently switched to non run-flat, gripper tires (Bridgestone S007A) and the problem went away.

 

^^^
Yep, it's much worse when cold, which is when I make "K" turns. It's NOT just the GM "chatter" GM also calls it 'hopping!" It hops when below ~50 but yes it makes some "noise" when it's warmer! Not enough for me to make "K" turns! For the little extra time it takes to turn the wheel less and make a “K” turn, I think about the ~1.2 "g" peaks I hit around the 75 foot fountain near the end of my street when it’s warm!

Yep as I said it goes away with lower performance tires that have a more normal slip angle! As I note, rubber tired cars don't use "full Ackerman" because it reduces the maximum lateral "g" capability. The Goodyears I had on my C6 Z51, same width didn't do it like the C7 Michelin's when cold. They also didn't perform like the OEM Michelin.

The reason I did the research was it was so bad at 40 F to 50F (doesn’t get very cold either in Eastern SC when I need to drive) and I got and early (September 2013 built) C7 Z51 when there was little info from GM. I recall a forum poster at that time when he backed out of a paring slot after dinner when he temp dropped it "hopped" so bad he got out and looked to see what broke. His wife wanted him to leave the car an call the dealer to flatbed it to their shop!

 

Thanks JMII for clarifying what Carfax does not do. Obviously, the front end problem on my stingray was not identified by the dealer that I bought the car from. I guess it's a case of buyer beware. Anyway I've been putting a lot of time, money and effort into this baby and she's really running great now! Here's a pic.....

 

The tires I'm running now have MORE grip then OEMs Michelin's.

 

Hmm, have not seen any street tire in a performance magazine test that generates more lateral acceleration at ~70+F than Micheline Pilot Super Sport Cup 2 ZP, which are somewhat better than the OEM Pilot Sport ZP.

Just checked TireRack and the Bridgestone S007A you mention are ~40% cheaper (in the Base/Z51 sizes, they don't have Grand Sport/Z06 rear size) if that is the goal. Until I see a Grand Sport tire that can achieve better that ~1.2 "g" peak lateral acceleration around the fountain near the end of my street I'll stick with the OEM tires! Note that's peak lateral "g" not a skid pad number!

The fact that it does not "chatter" IMO and from my research indicates they have higher slip angles. Their are racing tires that have very low slip angels and are "sticky" but need to have a few laps to get max traction. They would have lots of "chatter" at full lock low speed turns!

 

Sorry to be the one to say it, bur Carfax reports are notoriously unreliable.

 

My lap times improved on track when I switched to the Bridgestones. I found the OEM Michelin Pilot Super Sport ZP (not the Cup 2) had a sweat spot - cold they were average, warm they were great, but once hot? Greasy and terrible. The Bridgestone seem way more progressive in how they given up and start sliding. The Michelins were more abrupt and complained loudly at the limits. Didn't seem to suit my driving style on track at all. Can't comment on street driving because I never push that hard on the street, so to me both performed equally in that regard. However what I do know is the chatter was downright terrible on the Michelin's and just doesn't happen on the Bridgestones.

 

^^^
As you say, if they fit your driving style that is all that matters. They looked 40% less on TireRack so worth it.

As I discovered, rubber tired cars don't use full Acreman steering geometry by design as no need since normal slip angles partly compensates. At high speed, since the outside tire in a turn has much higher loading than the inside, it also hurts high speed "g" performance.

Of the many of my own references I used when defining the reason for high "chatter" in the C7 and when cold "hopping" I also found a good Internet reference that had a 165 page chapter entitled "Steering Dynamics." Below is a pic from one page (it has lots of math but some good pics as well!) As noted, to achieve the max lateral "g" force in a turn some race cars use "Reverse Ackerman!" Have an old text entitled "How to Make Your Car Handle" that said that but I questioned it because of the age. However this is a more modern reference! Doubt many if any still do that but chatter when leaving the pits is no big deal!

As I said, I don't Track and one of my favorite safe high "g" turns is a moderate speed one around the fountain at the end of my street! It's safe, not a home or person within 1/4 mile of the 4 lane highway at the end. Grass field on the right so if it "steps out" slightly no big deal. It's more like a turn in an Autocross.

 

That is easy to answer. CarFax tells you when something was repaired not when it went bad. If a bad control arm wasn't repaired then it is impossible to generate a CarFax report. As for having 7404 miles with suspension issues the ones you report are typical of a car that saw a lot of time on the track. The suspension bushings, links and wheel hubs take a lot of abuse on the track and will wear much faster than driving on the street. It gets worse if the owner used slicks to improve cornering speeds. Those bushings and bearings are checked for excessive play every time we get ready for a track event. Some people consider them as periodic maintenance items and replace them on a regular basis. Once per year for some items and once every couple of years for others.

Bill