Car jerks when turning
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It is the race car style Michelin tires. Especially the lower profile larger Z51's. Had the same size tires an "Ackerman" steering geometry on my Z51 C6 and it wasn't close to this bad. Gets much worse when below 40F. At 30 will feel like front end is falling apart if you use full lock at very slow speeds like when backing or pulling out of a parking place. Of interest folks who switched to all-season tires indicate the issue goes away or is significantly reduced. Did some research and summarized the issue in this PDF: www.netwelding.com/wheel_chatter.pdfSimple solution. When tires are cold don't make full turn, leave 1/2 turn from full lock and make a "K" turn!
Last edited by JerryU; Nov 7, 2015 at 10:59 PM.
My C7 is a September 2013 build and a DD so have experienced two winters. In 2013 someone posted they were pulling out of a parking slot on a cold night after the car had been parked for some time. He turned the wheel full lock and thought something had failed. He got out of the car and looked underneath. His wife wanted him to leave it parked and call the dealer to have it towed! If you have a Z51 and it gets to ~35F, be prepared or follow my previous advice and turn less than full lock when making slow turns! When I pull out of the garage in the morning, that's what I start doing around this time of year and make a "K" turn where in the summer no vibration or chatter at all. Even the non Z51 will experiance chatter, as GM calls it.
Last edited by JerryU; Nov 8, 2015 at 08:59 AM.
Last edited by BIG Dave; Nov 8, 2015 at 09:30 AM.


This is normal for a sportscar type of handling with very wide tires. Chill...
Elmer
just continue to blame GM and call it crap!! 
Racing type tires are built to have very low slip angles, i.e. turn the wheel and the contact patch follows instantly. The low profile run flat, stiff sidewall Michelins, especially on the Z51 are close to race car tire performance. When these tires are turned sharply at low speeds there is little movement or squirming on the surface. Even with some Ackerman steering geometry built in, one tire skids across the pavement causing chatter. A colder stiffer tire is worse. Ackerman invented and patented the idea of turning each front wheel at a different angle in small turning radius turns. He did that for horse draw carrages in 1816 and it can help at slow speeds.
But excess Ackerman geometry is worse at higher speeds where the tires operate at a different slip angles side to side since lateral forces are higher on th outside tire in a high speed turn. Suffice to say the steering geometry in the C7 is optimized for high speed performance not to make those unwilling to turn the wheel less on slow speed, sharp turns when it's cold!
If you are not willing to turn the wheel less, suggest buying an Impala, etc!

As mentioned my Z51 C7 is much worse at 30 to 40F than was my C6 Z51. Never had to turn the wheel less when pulling the C6 out of the garage on a cold morning with the OEM Goodyears or the Firestones I put on after. There as some chatter but minimal. With my C7 I do it when it's less than ~45F, no big deal!
Large Slip Angles Need Less Ackerman Geometry to Avoid Chatter, Since Tread Moves Reducing Sliding or Skidding. So C7 Owners Who Switch to All-Season Tires Have Reported the Chatter Issue is Eliminated or Significantly Reduced.
Last edited by JerryU; Nov 8, 2015 at 12:34 PM.
























