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Hoping someone will be able to shed some light on an issue I've been having with a 2015 Z06 with the Z07 package. I will try to keep this as short as possible, without skipping details:
The car is a 2015 Z06/Z07 with just under 21,000 miles. I purchased the car at the end of May. Driving down anything but the smoothest of roads, the car was very darty. More so than what can be expected from a car with wide sticky tires. I had an alignment done shortly after purchasing (done by local Chevrolet dealer). Front and rear toe were out of spec. After the alignment, it seemed a little better, but definitely not correct.
Right hand corners are of no issue. However, left corners there seems to be a "surge" in the steering. The best way I can explain this is if you enter a left hand sweeping corner and move the wheel from center (12 o'clock) to an 11 o'clock position to follow the road, about a second into it the car starts to steer further left...as if you had cranked the wheel to a 9 o'clock position. This also happens when you hit any road imperfections, it seems to over input the steering. To me, it seemed like a sensor issue.
I put the car on a lift and checked it over with a friend of mine. Nothing looked suspect. Nothing bent, nothing leaking up front, nothing that had appeared to have been repaired. We did notice that the passenger rear shock was weeping, but that was it.
Took it back to the dealership and had the steering angle sensor checked out. They indicated that everything checked out when they hooked it up (voltage). They said that it could be the rear passenger shock. Today I switched passenger rear shocks with a friend of mine who also has a 2015 Z06/Z07. Test drove it and no change.
I've driven 2 other C7 Z06's and they were quite planted...nothing like my car. Had my friend drive it and he said the same thing, that the car drives very sketchy.
Tires on the car are Cup 2's with a good amount of life left. The dealership had done a steering gear replacement prior to my ownership (recall).
Has anyone else experienced this? I'm really at my wits end trying to diagnose and the dealership hasn't been much help. I believe this would be an issue with a steering component, but it could also be something with the rear of the car.
Mike,
Have you checked all four of the wheel hubs to make sure one or more aren't loose? When you had the car realigned did you think to mark the LCA camber/caster adjustment cam positions? A slipping LCA can cause weird things to happen. One of the LCA cam bolts may not be tightened properly.
Thanks Bill, I did check for any wheel movement, everything was rock solid. I can double check the cam bolts, but this issue was also prior to the alignment.
The rear caster can be adjusted on these cars, but it takes a special tool to do it. The dealer I normally take my Z06/7 to didn't have that tool, so I had to shop around town to find a place that could adjust the rear caster. It was off by a bit, but after that alignment, its been rock solid.
To add a little more info to the OPs post, I have driven this car. As I was driving it in a straight line at about 50mph I would give the steering wheel slight left input (just a couple of degrees) there would be a hesitation and then suddenly the steering would surge and apply way more input. Causing the chassis to have a very unsettling feeling. The best way I can describe it is it’s almost like if the passenger reached over and suddenly shoved the wheel left even further. Mind you the steering wheel does not move any further. This is why I feel it is computer related not alignment or tires grabbing the road imperfections. As those would surely cause the steering wheel to move further.
I would manually select different steering modes in the menu(not with the ****) to see if this changes anything in just the steering. Doing it this way keeps the suspension setting constant.
I'm from the mind set try **** that's free first. So you had toe out which can ruin tires. You said you have a buddy with a Vette. Swap his front wheels and see if it's the tires. If not sounds like power steering or electric steering is wonky. Drive by wire I guess can have a mind of its own of its not working right.
from what I've been told is that the Z06 comes with a type of track alignment. Mine is a 2019 and does the same thing. Some roads are a lot worse then others. The wide stance rides on the edges of the tire groves on the road and has a tendency to follow them pretty badly. Try riding the edges of the lane a little bit to get out of the grooves and see what that does for you. Check with your dealership and see if they can do a more road friendly alignment.
from what I've been told is that the Z06 comes with a type of track alignment. Mine is a 2019 and does the same thing. Some roads are a lot worse then others. The wide stance rides on the edges of the tire groves on the road and has a tendency to follow them pretty badly.
No C7 came from the factory with a track alignment.
Tramlining is caused primarily by wide tires. What the OP describes is not tramlining, but a fundamental issue with the car.
I'm sorry to hear about this, it sounds like the sort of issue that can take what was once a dream to own a great car and turn it into a disappointing regret. The C7 is a great car, it's really a shame you are experiencing this.
Is the car at stock ride height?
What you describe sounds like something is moving in a way it is not supposed to. Like a bushing is gone and allowing a major suspension component to shift.
I would seek a 2nd opinion on the alignment, and have the tech inspect all bushings for movement.
The steering wheel is locked to the wheels, meaning the front wheels cannot turn further than the input into the steering wheel, unless there is major defect in the rack and I believe you would feel that as play in the steering.
Purely a guess, but perhaps a glitch in the steering angle sensor?
I'm thinking something like a dead spot in the sensor that causes the power steering to not sense the initial movement to the left, then as the steering angle increases, the system sees the steering angle again and thinks it's seeing big /fast steering input.
Another suggestion - If you put the car in Track mode with the PTM mode "race" it will dial back the traction control and disable stabilitrack completely. Then you can test carefully and know it's not likely either of those systems.
Another thought I had was if there is a malfunction in the eLSD differential system it could be locking the rear diff under normal straight line driving, making it hard to turn, then unlocking it after it senses your turn therefor making it suddenly turn easier? Not sure how to test that, is there a fuse for it that can be removed possibly?
"Dartiness", like you describe is almost always due to a loose part or toe out. Excess negative camber can also affect this problem. Of course, negative castor can cause it too, but I do not think you can adjust this car to get negative castor. If the car tracks straight without trying to pull to one side, then castor is not a problem. Since you only have 15k miles, I doubt any parts are worn out yet...although it could be possible.
Bring the toe in and it will drive like a new car...and this could be at either or both ends.
The FSM has several things you can check. One of them is the steering wheel torque sensor. If that is not working correctly or there is something binding/sticking which affects steering wheel torque I imagine that could cause a surge in steering. I am going to post a selection of pages out of the steering diagnostic. Since you had the steering angle sensor and the alignment checked out I am not going to include those parts.
I doubt it is a stability control malfunction since based on your description it doesn't seem to exhibit the characteristics of a sudden brake application on one of the wheels as stability control does to control yaw.
Hoping someone will be able to shed some light on an issue I've been having with a 2015 Z06 with the Z07 package. I will try to keep this as short as possible, without skipping details:
The car is a 2015 Z06/Z07 with just under 21,000 miles. I purchased the car at the end of May. Driving down anything but the smoothest of roads, the car was very darty. More so than what can be expected from a car with wide sticky tires. I had an alignment done shortly after purchasing (done by local Chevrolet dealer). Front and rear toe were out of spec. After the alignment, it seemed a little better, but definitely not correct.
Right hand corners are of no issue. However, left corners there seems to be a "surge" in the steering. The best way I can explain this is if you enter a left hand sweeping corner and move the wheel from center (12 o'clock) to an 11 o'clock position to follow the road, about a second into it the car starts to steer further left...as if you had cranked the wheel to a 9 o'clock position. This also happens when you hit any road imperfections, it seems to over input the steering. To me, it seemed like a sensor issue.
I put the car on a lift and checked it over with a friend of mine. Nothing looked suspect. Nothing bent, nothing leaking up front, nothing that had appeared to have been repaired. We did notice that the passenger rear shock was weeping, but that was it.
Took it back to the dealership and had the steering angle sensor checked out. They indicated that everything checked out when they hooked it up (voltage). They said that it could be the rear passenger shock. Today I switched passenger rear shocks with a friend of mine who also has a 2015 Z06/Z07. Test drove it and no change.
I've driven 2 other C7 Z06's and they were quite planted...nothing like my car. Had my friend drive it and he said the same thing, that the car drives very sketchy.
Tires on the car are Cup 2's with a good amount of life left. The dealership had done a steering gear replacement prior to my ownership (recall).
Has anyone else experienced this? I'm really at my wits end trying to diagnose and the dealership hasn't been much help. I believe this would be an issue with a steering component, but it could also be something with the rear of the car.
Any input would be greatly appreciated.
Thanks in advance-
Mike
Get a steeet alignment. Mine was that way until I had the alignment done. Also tires have a lot to do with this. Cup tires on the street probably contribute to this. I plan on going with as/3 -as/4 Michelins.
These cars don't respond well to stomping on the throttle.
Thanks everyone for the input, it is really appreciated. I will start with the settings and then move to having the alignment rechecked and steering system. I too am suspicious about the steering gear having been replaced. The steering wheel torque sensor seems like something that could be causing the steering issues I am experiencing. Once this is figured out I will report back with the findings.
Check the rear caster with the special tool that is required. I guarantee 99 out of 100 techs don't know how to adjust a C7 correctly. I had mine back on alignment rack today. I had to guide the tech thru getting the proper setup. I own the tool and know how it's done. If rear caster is off it induces "bump steer" during turns or when accelerating. Caster in the rear needs to be close to 0 deg. Otherwise funky things start to happen. You turn left and it compresses the right rear tire and the toe changes and the tire turns right. At the same time the left tire is in rebound and it turns right also. Now you have the front wheels wanting to go left and the rear is going right. This causes severe uncontrolled oversteer. Just what you are describing. I guarantee if they touched the rear setting without checking caster(which you can't do without the proper tool) they screwed it up more than they helped.
BTW the rear adjustment is a PIA even if you have the tool. We spent a lot of time on mine today as well as two weekends ago.
Finally right now. Mine was not as severe as you describe. I had to travel at higher speed and make faster steering inputs for it show up as scary unpredictable rear end movement. I am tracking mine for the first time since i got it a couple months ago later in Oct and it needs to be right. And I have felt it was not right since day one I purchased the car in June. And I have tracked every car I've owned in the past 25 years. Mine actually had neg caster on one side and pos caster on the other so the rear tires were trying to go opposite directions in hard turns.
09-24-2022, 05:14 PM
C7 Z06 Handling Issue
