jbeidl

I have a 2017 Grand Sport built on 7/28/2016 and placed in service on 8/31/2016. Car currently has just a little over 2500 miles.

I have not noticed anything obvious while driving in automatic mode, however I did capture the AFM RPM variations using my PDR.

I am going to start driving in Manual mode only.

Cruise was enabled in Drive at start of video. At around 5.3mi I switched mode to Manual and RPM variations stopped.


John

Mr. Jones

I added my data to the chart. Data is a little incomplete due to the car being at the dealer right now. They called and said they flushed the trans, I think he said three times.
Car 2016 Z51 early production likely 7/2015.
Tach is swinging 200rpm constantly when in V4.
I get a vibration/rumble in V4 once everything is good and hot.
switch to manual and problem goes away.
Shifts into gear every day and after long sit right away.
First to second and or second to third are inconsistent.
Full throttle shifts are great.
No over heating.
Car has 13,000+ miles
they want two trips min. 200 miles total with full heat cycles.
The trip home from the dealer is 95 miles so That should not be a problem.
After the 200 miles and heat cycles verify the problem is gone or still there.
I expect to change the Torque converter next.

Can someone confirm that the V4 tach/slip should only be 10rpm.
I read that here but seams near impossible with it locking and unlocking.
I told the service rep. it drives like a 1982 Chevy with a bad lock-up converter-he knew what that was.

Updated the chart. They did do 3 flushes. Car shifts much better in all gears. No vibration/rumble but it still looks like 100 rpm swing on tach.
I will complete the 200 miles and keep an eye on it.
Later, after I get some miles on it I will hook up the computer and see what the real rpm fluctuation is and report back.

NSC5

10 RPM maximum slip is correct according to the GM TSB; of course that has to be read with the diagnostic tool since the resolution of the car tach isn't sufficient. There are numerous updates to this TSB, here is one variant but there are later ones: https://gm.oemdtc.com/6597/pip5337e-...-chevrolet-gmc

hanks

Just got my 2016 back and had the torque converter replaced along with Mobil 1 fluid. Runs great. Big difference in the smoothness of the shifting.

jbeidl

NSC5 pointed out that the Tach display does not provide enough resolution to verify that AFM RPM remains within 10RPM.

My previous capture displayed that the RPM varied by a fair, but unknown, amount. Today I took a PDR capture as well as a scantool capture.

Scantool used was a OBDLink MX Wi-Fi Scan Tool from scantool.net. Data captured on my iPhone with the free iTunes OBDLink App.

I selected the scantool data taken around the time where I changed modes from Drive to Manual (about 3.1mi in the video). I have attached the captured data as an xls file as well as a screen shot of the chart.

The RPM variations can been seen just before the X Axis value of about 51, I switched to Manual Mode just about at that point. The RPM variations are around 120RPM, much greater than the 10RPM limit.

The only thing I have ever noticed while driving is a hard 1-2 shift shortly after a cold start. This occasionally happens at about 3 miles from home where there is a stop sign and then a 90 degree right turn.

I plan to provide this data to my local Corvette service department but I am not sure I will do anything yet. I am still not convinced that GM understands the root cause of this problem.

John

joemessman

That's definitely abnormal. On level ground I cannot feel or see a fluctuation. When going up a slight incline you see very very little fluctuation and can't feel it. See my signature for what car I have.

ronkellogg

update

Well my elation with thinking my car was fixed was short lived. Although the torque tube and torque converter really improved the vibration at first, I still noticed some shutter but it did seem less. I drove my Z06 to the Corvette Museum Birthday Bash this past weekend from Southeast Tennessee going up backroads in some heavy rain. I did notice the shutter. Returning home Sunday morning I ran I65 South to I24 East and the vibration is back and worse than before. I feel a rhythmic vibration, which at times I think I can hear, starting from the front of the car in the steering wheel and then the seat and then smooth every 2.5 seconds. It gets worse with speed. I did notice vibration coasting with car in neutral. My C2 rides smoother on the interstate. I checked shutter by running 75 in 8th gear then putting in manual mode and shifting down to 7th. My understanding is that it turns AFM off. Acceleration made shutter worse although it’s hard to distinguish between shutter and the vibration. Chevrolet Executive office had me to take it back to the dealer yesterday. 4th time to the dealer since June and I can’t express how disgusted I feel having a beautiful Laguna Blue Z06 convertible that shakes all over the road. Have no idea what’s next but I want it fixed or replaced. Talked with Chevy Executive Office and brought up subject of either fixing it this time or replacing car. She will tell district manager.


Just talked with dealer. another road force balance and some more new tires.

Sean Tex

I haven't read all the posts and honestly I was just checking out what Z06 owners are saying about their overheating problems and wondering if they know about the class-action law suit filed by Hagens Berman on 6/14/2017 against Chevy for promoting the Z06 as a track ready car, which I can say it is not. I have joined the law suit.


I took mine out on track for the first time a couple of weeks ago and though I'm in north Texas it was a cool August day and it rained 4 of the 5 sessions I was able to get in, thanks to Harvey ..... it overheated and went into limp mode 20 mins into the 1st session and I was not going anywhere near flat out. It didn't overheat on the next 3 sessions as speed was greatly reduced due to the rain. The last session was light rain and the track a little drier and again after 20 mins it overheated and I also got a service warning for the power steering which had stiffened up significantly.


After the weekend I drove it 40 miles back to the Chevy dealership without any issues and they found nothing wrong.
I have a Callaway SC757 supercharger and the service manager at the dealership told me it would only last 10 mins without this addition.

Just waiting to hear back from the lawyers if I'll still have a claim against Chevy if I add an aftermarket cooling system.

vettnut

I just inquired on a 2015. GM bought this corvette back. Transmission was rebuilt due to harsh shifting. Supposedly repaired and comes with all remaining warranty and an extra 12 months bumper to bumper warranty.
GM buyback: should I run away from this deal. They have been very open. For sale at a chevy dealership. 15000 miles. Different title now.
RG

767guy

0n the plus side it sounds like the dealer is being really up front with you.
My advice to you is based on the experience I had with my early built 2015 base ( non Z51,non Z06) which is a daily driver for me here in Ontario during the summer and a DD for 6 months in Florida.
* First noticed shift issues at 2500 mile mark
* Was told it is normal, adaptive learning , waited to the 12000 mile mark before I could bring my self to having the rear end of the car torn apart for a TC change out
*At about the 18000 mile mark a complete transmission ( includes TC) due to all the shift/shudder issues, again,
*Again, after another aprox 6000 miles of driving all the shift crap was back and they replaced the TC again. This time on the evasive tear out a large well known Florida dealer damaged the rear bumper cover doing the job
* After both the second and third tear outs I had rear half axle shafts that failed........is that just a coincidence?
* There were other shop visits for a number of trim and mechanical issues. The drivers door panel and sill plate looked like they had been through a safety shoe/boot war.

Dealer and GM stepped up to the plate, to their credit, and I am driving a trouble free 2018 , base ,A8 , BUT..BUT I only have 2000 miles on it so far.Fingers crossed as I really enjoy owning and driving the C7.
The 2015 driving experience was a nightmare that lasted for 30 months.
In my case and too often on this forum I read about TC changes that seem to work initially but then some have reported they have had to go back again. Probably because the issues went beyond the TC .
As an owner of a car that has had a tear out at resale can you boast that you have a 2015 that is fixed OR will others walk away.
I could not get more than 6000 miles between tear outS. Many have reported that after a new TC their car drives great. I hope it stays that way for their sake. I hope I dont read about repeated failures after several thousands of miles.
Based on my experience and other on this forum a car that has drive line issues may have additional problems that go much deeper and beyond a TC changeout.
To consider the buyback with driveline history, even if the price was discounted thousands of dollars below normal retail, I would never go there............RUN LIKE HELL !

Heidemarie

Heidi
Save the Wave

Jay_Davis

Interesting. I've had the same nightmare, plus I also had tons of shifting issues, including violent ones, for two years before they replaced the transmission. I also had to have a half axle replaced and the torque tube after that. After seeing what you wrote, maybe it really is all related. To top it off, then the engine failed and GM doesn't want to cover it because none of this could possibly be their fault. All these issues couldn't have possibly stressed the engine bearings until they failed.

767guy

^^^ Yup, when they have to go that deep into the car it just presents the risk of fixing one thing only to screw something else up. Many of us have seen the bulletin posted on this form detailing how critical the re-installation of drive line components is. It describes how critical the torque tube and flex plate installation is so as to not take out the crank bearings in the engine.

GaryPitts

How does the dealer measure TC clutch slip? Is all of that data available with the OBD port?

toph1206

I responded to another threat but adding here - GM is replacing my A8. The can would "jerk" when put into drive after sitting for a while. Tech said they would have multiple parts to replace to the engineer said to just put a new trans in. Apparently multiple parts have been updated in the latest one.

beadman

Mine is a '15 with 17k miles. With the 5 year power train warranty was wondering when to have my darling go under the knife!

Thanks

c6reaperx

2016 Z51 20k miles, torque converter being replaced right now.

joemessman

At what point in miles did you start having issues? Sorry to hear about it. That darn GM for installing a marginal drive trains on these and the rest of their cars. I'd like to be a fly on the wall when all the big wigs at GM discuss this elephant in their living room. I'm sure they can't ignore it any longer.

c6reaperx

I noticed some “shudder� every once in a while around 1k miles ago. Seemed to get worse each time I drove, to the point that I had to take it in. Shifting was sluggish so I was hoping for a software flash at least. Car has been at the stealership for about two weeks and I finally got a reply today.

Was also getting a flashing cil at the same time. Tech says it’s related, time will tell.

R8Z51

[QUOTE=Chafey69;1595368659]I just picked up a '16 after owning two '14s and I can already tell this transmission is no where near as smooth as the A6. Putting the car into reverse or drive and the whole damn thing shudders. I haven't had any problems when going into V4 mode, yet.