jimmbbo

After some research, it is apparently a common problem with the C7, caused either by the hot radiator exhaust from the top of the hood being sucked into the cabin air inlets at the base of the windshield, or inadequate insulation of the cabin air inlet ducting allowing engine bay heat to transfer into the cabin vent air, or a combination of both.
Reported solutions are to
1) use the A/C, or
2) turn on the A/C to precool the ducting (which lasts for an indeterminate period of time) or
3) use outside air from only the lower vents...
I have yet to confirm these theories, so YMMV
FWIW, One owner tried insulating the ducting with sitck-on mylar backed insulation padding, and the pads melted...

csysman

I just picked up my car yesterday - when leaving this evening the steering felt like a 4 wheel drive when making a turn notchy and chatter from frt wheels - what causes that ?
and they say thats normal -" cant believe it - "
can some one explain this to me .... please
csysman

Larry M

Ackerman affect
Tires get cold and hard, doesn't help how wide they are

I hate these tires. I'm likely not going with these tires when it's time to switch

csysman

i wonder if anyone had success reducing that condition after switching them out ?

FunDriver

Same here. Also have a 2016.

Larry M

In my personal experience, I went from Goodyear GS-D3 to Continental DW on a 285 tire (Trans Am) and it went away at 30ish degrees.

The GS-D3 would do it at 40*

These Michelin tires seem to at 55*

pdiddy972

I just avoid tight turns when it’s cold outside. Not a big deal.

bigsapper

On my 2016, I switched out the front tires for Michelin Pilot Sport 4S (non run flat). Didn't really help the low speed skipping.

50th year

rough 1st to second shift with the a8 when cold or first shift of the day

SIRFLOW

Soo, on the topic of normal vs not: when i am filling the gas tank, the nozzle will not just pump gas on its own. What i mean is, you push in the little latch and it immediately shuts off as if it was full. in fact, even when just holding the lever on the handlepiece down, it will frequently stop fueling with the usual "thunk" as if the tank were full, even though it could be nearly empty...

any one else experience this? is it the angle of the fuel port? is there a secret to it? how do i get the damn tank full with out fiddling with the pump handle!?!

ExRedRacer

I switched my "Summer Only" OEM's 2 months ago so I could drive with confidence during our colder (mid-20's - 40's) months. I got a set of Michelin All-Season Pilot Sports and there is no chatter whatsoever even on cold, wet pavement.

These new tires do not turn rock-hard when the temps go below 40-45 degrees or so as do the summer tires, so consequently they don't make all that noise no matter how tight the turn. And for all practical purposes, they handle just as well as the summer variety in 99% of the driving anyone would do.

Skid Row Joe

Rough Idle - I wasn't expecting that.

owc6

This is a well-known issue, and to date not solved from the factory. Turning the nozzle upside down when filling usually solves this. Some of us have success with slowly turning it down to the normal fueling position after a few gallons have been dispensed.

Some individual pumps are chronic offenders, and others are OK. Those of us with this problem avoid the known pumps that are problematic.

767guy

Yes, replaced the OEM tires on my 2015 with Michelin AS 3+ ( all season tires)

*No scrubbing in slow speed wheel lock turns
*not as sticky, does not throw as much debris/gravel
*no reduced braking/grip in cold weather
* no sidewall cracking issues in very cold weather
*perhaps a bit quieter.
*Can not tell the difference form OEM tires unless looking at the script on the side wall or closely examining the tread pattern

....Took delivery of my 2018 late June and first trip was to the tire shop to pull off the OEM's and replace with Michelin AS 3+.

767guy

Lisa, my 2015 behaved as you have described but the 2018 does not seem to have this issue......don't know if GM has made a change or the new car just "works different"

JerryU

Yep, this is an explanation I found after doing the research when I got my September 2013 built C7 Z51. Same width tires as my C6 Z51 and the "chatter" or "hopping" as GM calls it is MUCH worse! Worth knowing to explain if you have a friend in the car and foolishly make a full lock turn when leaving a parking slot on a cold day! They will tell surly all your other friends what a "piece of junk you bought!"

This is what it is NOT!
Ackerman Steering Geometry (or properly said "Lack of Full Ackerman Steering." Proof, it goes away with winter tires or mostly with all-season tires and the Ackerman steering geometry didn't change!

Sticky Tires-it's worse with cold tires and when wet where they are NOT sticky!


It's the race car type very low slip angles of the Michelin tires! That helps them achieve very high lateral "g's" in warm weather but causes chatter when cold.

Turns our no manufacturer uses full Ackerman compensation as the tire slip angle partially provides the needed difference in front tire turning radius on slow speed turns. Using full Ackerman would reduce the max "g" force when warm.

SOLUTION: Don't use full lock when it's below 45/50 F on slow speed turns- make "K" turns! In the Spring, Summer and Fall I make a full lock turn after backing out of my garage to turn down my driveway. On a cold Winter day I turn the wheel about a 1/2 turn from full lock and make a "K" turn. Hopping doesn't do any harm but I don't like it!

PS: I love the tires! When taking the time to make a "K" turn I think of the 1.2 "g's" I hit on my favorite 270 degrees off-ramp when it's warm!

Lots of detail and pics/test in this PDF! http://netwelding.com/Wheel_Chatter.pdf




Some of many pics in PDF

JerryU

It happened to be ~20% of the time in my 2014 and about the same with my Grand Sport.

Some reports of the pump not shutting off when nozzle placed upside down. I find whenever it's encountered I turn the pump handle 90 degrees CCW. I can then depress the level fully for max flow. I have always found it trips automatically.

As you note, it is dependent on the full tripping mechanism on particular pumps and how it's adjusted.

shootervince

Unless its a cop

JerryU

^^^
And every AH who is barreling up in the left or right lane on an Interstate and will be in what folks traditionally call "Blind Spots" immediately right behind each fender! In fact I am looking at all mirrors all the time and the reduced viability out of the rear window in a C7 made me add a small blind spot mirror! Never needed one in my '88, '93 or 2008 Vettes but the C7 has reduced rear viability. Defensive driving requires knowing where all cars are around you or soon will be!

In fact, the Stage 2 aero option I have on my Grand Sport with it's spoiler extensions on the ends makes in almost as bad as a Vert with the top up!

bigsapper

There are 2 flaps in the nozzle tube. You have to have the nozzle inserted completely.

That's also why you get the extra nozzle insert. So if you need to add gas via a gas can, you put the insert in first to make sure it gets past both flaps.