jeff1999

I have a 2015 A8 Z51. And when I begin to leave my parking spot and I turn the wheel in either direction there is a crunching sound coming from the wheel well area and the feel of the steering wheel feels like your running over a rock. It disapates a bit as I starts driving but always come back after several hours and a restart. Is this normal?

speedlink

Yes, its inherent in the steering geometry and tires in the C7 and other generations. Don't worry, its normal.

meyerweb

Page 10-67 of the owner's manual:

Search this forum for "Ackerman" and you'll find lots of information about it.

Edit: You might find this thread helpful, too:

https://www.corvetteforum.com/forums...ette-does.html

jeff1999

I appreciate the comments and thank you. It just feels like the wheel is about to fall off everytime this happens.

eboggs_jkvl

Mark it down as normal and forget about it. I try and remember not to turn it as hard as I would like when doing slow tight maneuvers.

Elmer

Bill Dearborn

It should occur in all tight low speed turns not just after an engine restart. The only time you won't notice the bumping/noise is if you are turning on a very low grip surface like ice. Then you will just notice the front of the car not turning as quickly as you might think it should.

Bill

aj98

OP is in NY, so I'd bet temperature is likely playing a part as well, especially if the "after restart" is a couple hours after shutting down. (where tires have cooled off)

Steve Garrett

Jeff, it IS the Ackerman Effect....this won't happen when it's warm outside.

alamo1974

Yes, C7 Corvette mine does the same.

JoesC5

Does it happen when you turn the steering wheel a small amount, say 1/4 turn, or only when the steering wheel is turned full lock(almost full lock)?

JerryU

It gets worse as the tires get colder! Starts around 45 F but wait till it gets to 35 and the car has been sitting! It's the Michelin very high performance tires! My Z51 C6 did not have it to any significant degree and it had the same width tires. Folks who switched to all season tires say it's eliminated or significantly reduced. Since I lived with it for 2 winters, now going into a 3rd, I made this PDF that explains what it is and why the tires are the key, especially the Z51:
http://netwelding.com/Wheel_Chatter.pdf
Useful info in case you have a friend in the car and you forget and turn the wheel fully when pulling out of a parking spot when it's 35F. He'll tell all your friends what a piece of junk you bought!
The simple solution is make a "K" turn rather than turn the wheel full lock! I know what it is but on a cold morning when backing out of the garage I do that rather than feel like the front end it about to fall apart!

eboggs_jkvl

Steven, I think it will happen 365 days a year no matter what the temperature. The suspension geometry does not change with the temperature and the car will hop when full (or almost full) lock of the steering wheel happens and the speed is slow.

Elmer

JerryU

In the summer I have no chatter when backing out of my garage at full lock. When it gets to about 45 chatter starts. If I use full lock at 35F it's so bad you'd think the front end is coming apart, it literally hops! Your right the Ackerman geometry doesn't change with temperature, as mentioned it's the tire construction. Folks who switched to All-Season tires, even on a Z51 have posted that the issue goes away or is significantly reduced. Below are two pics from my PDF that help explain it. There are many more pics and a full explanation in the PDF, see post #11 above.
Never had the issue to any extent with the Goodyears or Firestones in my Z51 C6 with the same width tires. Always used full lock when backing out of my garage in the morning even at 35F! The C7 Michelins are much more race car type construction! With my Z51 C7 I make a "K" turn when it's 45 or below!



Tires with more slip angle move differently side to side when making a slow speed turn at full lock. The racing type construction with the OEM Michelins, especially the Z51, move very little!



All-Season Tires have a greater slip angle so don't need as much Ackerman geometry.

u115266

OUTSTANDING HELP from all you you folks here......so glad I joined up and researched my problem. Had my wife and I worried. Some really smart folks here for sure, as well as very helpful. Can't thanks all of you enough.

mikez06

Happens no matter what the temp (mostly drove in hot) for mine.

JerryU

Perhaps you haven't driven your C7 at full lock when it's 35F! I have and it literally feels like the front end is coming apart!
In the summer I use full lock when pulling out of my garage and there is hardly any scrubbing, and if warm enough - none. As noted in my above post #13 with pics, agree the steering geometry doen't change but the tire when cold is so "stiff" (particularly evident in the lower profile Z51) the tread surface does not move relative to the carcass so the Chatter, as GM refers to it or hopping, which may be more descriptive, is very sevear.

mikez06

True, don't have the C7 out in 35 degree weather.
Just my experience the tire 'clunks' no matter if warmed up or cold.
My tint guy asked what the frick was wrong with those tires? I said you'll be doing enough C7's soon (back in Nov. 2014), you'll also get used to it! Takes some getting used to for sure.
(And no full lock turns)

C7Joy

It does feel weird, doesn't it. You should see how mine hops when I turn around in my driveway!

rrsperry

Switching to A/S tires for the winter cured the problem. (z51 sizes) It reminded me of the race car with the locked differential. (rear vs front, but the same effect)

blegler141

Got my '15, Z51 vette 6/2015 and was extremely pleased with the car. I had no problems until Nov. Steering was perfect, NO wheel or chatter from the front end. Then it started. When turning full left or right the steering wheel almost jerks from my hands and the thumping is very loud. Feels like the tires are coming off the wheels. After taking the car to the dealer I was told the this is "normal". Others say its cold weather. I live in SW Florida so I would hate to live in N. Dakota, I wouldn't be able to drive. I have a hard time believing this explanation. It just keeps getting worse.
Why can't GM fix this? What has to happen to get this resolved? I'm afraid to drive this car. I have driven only 4K miles. HELP!!!