Actual date change was Sept 29th 2014

 

[QUOTE=JoesC5;1591105570]HMMM. I sure hope his experience is an anomaly. If mine doesn't get any worse I'll live with it. If it does get worse I'll have it checked out at my first oil change. Just need to decide which dealer. Probably will go to Criswell as they service a lot more Corvettes than any of the dealers closer to me. I'm beginning to think the A8 performs better if it is driven harder. I started a couple of days ago.

 

[QUOTE=rmorin1249;1591105537] These cars can be taken to the race track.Would you drive it easy at the track?These cars were built to drive hard.

 

I've noticed that, too, but I think it is a bit better since doing the latest software update and "fast learn" procedure. It was never glaring or something that made me think it was causing any damage.

 

After 7 weeks at the dealership with them trying the learn procedure (what a joke) and the GM engineers not wanting to spend a buck they finally replaced the transmission and it is perfect , no shift banging no jolts no pulsing in and out if 7th gear and no automatically down shifting to 4th at interstate speeds. I am completely convinced GM engineering could not diagnose a cracked windshield if they were looking through it.

 

Glad you finally got a new tranny. My issues are very minor. If they continue I will have my tranny evaluated at my first oil change.

 

How many miles did they pile on the car while they had it?

 

Over 300

 

I sure wish I could drive my car and enjoy jerk and bang free shifts. GM just doesn't want me to be able to enjoy my car it seems refusing to repla e mine as well. Im very happy to hear they replaced the transmission. How did they compensate you for the added mileage and needless wear and tear they did to your car before doing what they should have done in the first place.

 

They have not gotten back with me yet, I picked my car up Friday and have driven about 100 miles to check it out and so far it works great.

 

I drove my car today for the first time since performing the road learning procedure. No hard shifts even though it did get below freezing last night. Temp was around 40. No hard upshifts or downshifts. The 3-1 downshift when coming to a stop is also much better. Also tried manual shifting both up and down. No issues. Not sure if the road learning procedure really did help but it sure didn't hurt. At this point I see no reason to take it to the dealer.

 

Where is the "Road Learning Procedure" found via the CF forum?

 

Google GM TSB 14-07-30-001c

Transmission Adaptive Functions and Correcting Low Mileage Harsh Shifts – 2015 GM Vehicles
BY VITALY
ON JANUARY 27, 2015
IN 2015, CADILLAC, CHEVROLET, CORVETTE, DIAGNOSTIC TIPS, ESCALADE, GMC, SIERRA, SILVERADO, TRANSMISSION, YUKON
Information on Transmission Adaptive Functions and Correcting Low Mileage Harsh Shifts – (Jan 27, 2015)
Subject:
Information on Transmission Adaptive Functions and Correcting Low Mileage Harsh Shifts
Models:
2015 Cadillac Escalade, Escalade ESV
2015 Chevrolet Corvette, Silverado
2015 GMC Sierra, Yukon, Yukon XL
Equipped with 8L90 Automatic Transmission (RPO M5U)
Attention:
This Bulletin also applies to any of the above models that may be Export vehicles.
Some customers may comment on low mileage vehicles with automatic transmission that shift feel to be too firm (harsh) or may slip or flare. Customers should be advised that the transmission makes use of an adaptive function that will help to refine the shift feel while driving and improve shift quality.
Transmission Adaptive Functions
The Hydra-Matic® 8-Speed RWD transmission utilizes a line pressure control system during upshifts to compensate for new transmission build variation as well as the normal wear of transmission components. The variation experience on a new and normal wear of the apply components within the transmission over time can cause shift time (the time required to apply a clutch) to be longer or shorter than desired.
In order to compensate for these changes, the transmission control module (TCM) adjusts the pressure commands to the various pressure control (PC) solenoids to maintain the originally calibrated shift timing. The automatic adjusting process is referred to as “adaptive learning” and it is used to ensure consistent shift feel plus increase transmission durability.
The TCM monitors the A/T input speed sensor (ISS) and the A/T output speed sensor (OSS) during commanded shifts to determine if a shift is occurring too fast (harsh) or too slow (soft) and adjusts the corresponding PC solenoid signal to maintain the set shift feel. The purpose of the adapt function is to automatically compensate the shift quality for the various vehicle shift control systems. The adapt function is a continuous process that will help to maintain optimal shift quality throughout the life of the vehicle.
How to Adapt Your Transmission
Transmission adapts can be reset and relearned on most vehicles through GDS 2 by using the Transmission Adaptive Values Learn procedure. This procedure is completed in the service stall and no vehicle driving is required.
To complete the Transmission Adaptive Values Learn procedure enter GDS 2 Diagnosis and navigate to:
Module diagnostics
Transmission Control Module
Configuration / Reset Function
Transmission Adaptive Values Learn
Transmission Adaptive Values Learn is the recommended method to reset and relearn the adapts. This procedure is available on all trucks. This procedure is also available on Corvettes built on September 29, 2014 or later. Use the Investigate Vehicle History (IVH) to verify the build date of a Corvette.
Important: Transmission Adaptive Values Learn is shown as an available GDS 2 procedure on all 2015 Corvettes built before September 29, 2014. This method is not effective and will not reset and relearn the adapts. These cars must be driven to learn the adapts.
For Corvettes built before September 29, 2014 the Hydra-Matic® 8-Speed RWD transmission adaptive learn process can only be accomplished by driving in the following manner. Execute the steps below with the vehicle warmed up on a smooth level road. The driver may observe a brief pulse behavior or firm shift feel while the transmission is optimizing the clutch learn characteristics.
Perform a test drive and note any soft or harsh shifts.
To improve these complaint shifts, locate the clutches that need to be learned in the following table below, and perform the required learning procedure for each clutch listed below the chart.
Note: The transmission fluid temperature must be between 75°C (167°F) and 85°C (185°F) during the drive procedure or adapts will not be learned.
To Correct The Shift Feel
Learn These Clutches
Applying Clutch
Releasing Clutch
1–2
C4
C3
2–3
C3
C1
3–4
C5
C3
4–5
C3
C4
5–6
C4
C2
6–7
C1
C4
7–8
C4
C3
3–1
C1
C4
2–1
C3
C4
N-D
C3 – Perform garage shift adaptive learning
N-R
C5 – Perform garage shift adaptive learning
Power Downshifts
Just perform the shifts and they will adapt
Note: During low vehicle speeds with no accelerator pedal input downshift will most likely be a 3-1 shift.
To Learn C1:
Shift the transmission into 6th gear with the PRNDM in the M position. Obtain an engine speed between 1000 and 1750 rpm. Maintain this condition for a total of about
5 miles (8 km). Cruise control may be used and has been found to result in faster learning of the clutch values. Try the complaint shift to see if it has improved to an acceptable level. If not, continue with operation in this speed range until the complaint shift improves.
To Learn C2:
Note: Perform abbreviated coast down shift adaptive learning procedure listed below to enable learn mode.
Shift the transmission into 8th gear with the PRNDM in the M position. Obtain an engine speed between 1000 and 1750 rpm. Maintain this condition for a total of about 5 miles (8 km). Cruise control may be used and has been found to result in faster learning of the clutch values. Try the complaint shift to see if it has improved to an acceptable level. If not, continue with operation in this speed range until the complaint shift improves.
To Learn C3:
Note: Perform abbreviated coast down shift adaptive learning procedure listed below to enable learn mode.
Shift the transmission into 4th gear with the PRNDM in the M position. Start a slow acceleration at about 1000 rpm and maintain the slow acceleration until you reach about 1650 rpm. Once you reach 1650 rpm, go back down to 1000 rpm and repeat the slow acceleration up to 1650 rpm. Repeat this a few times and re-try the complaint shift to see if it has improved to an acceptable level. If it has not, continue this slow acceleration procedure until the complaint shift improves.
To Learn C4:
Shift the transmission into 7th gear with the PRNDM in the M position. Obtain an engine speed between 1000 and 1750 rpm. Maintain this condition for a total of about 5 miles (8 km). Cruise control may be used and has been found to result in faster
learning of the clutch values. Try the complaint shift to see if it has improved to an acceptable level. If not, continue with operation in this speed range until the complaint shift improves.
To Learn C5:
Shift the transmission into 3rd gear with the PRNDM in the M position. Start a slow acceleration at about 1000 rpm and maintain the slow acceleration until you reach about 2500 rpm. Once you reach 2500 rpm, go back down to 1000 rpm and repeat the slow acceleration up to 2500 rpm. Repeat this a few times and re-try the complaint shift to see if it has improved to an acceptable level. If it has not, continue this slow acceleration procedure until the complaint shift improves.
Abbreviated Coast Down Shift Adaptive Learning:
Lightly accelerate to 65 mph (105 km/h) and coast to 25 mph (40 km/h) (light braking can be applied). Repeat 10 times.
This procedure will enable clutch apply adaptive learning for the C2 and C3.
Note: This only needs to be performed once per drive cycle to enable the adaptive learning for all subsequent C2 and C3 learning maneuvers. Failure to perform this procedure will result in no learning of these clutches.
Power Downshift Adaptive Learning:
Starting with the vehicle operation in 8th gear, slowly apply pressure to the accelerator pedal until downshift occurs. Repeat as necessary in each gear (8, 7, 6, 5, 4, 3 and 2).
This procedure will learn the off-going clutch adapts for desired power downshift control.
Garage Shift Adaptive Learning:
Perform abbreviated coast down shift adaptive learning procedure. Then with the vehicle at a stop, hold foot on brake pedal and move the shifter from Neutral to Drive and Neutral to Reverse. Repeat as necessary until desired shift quality is achieved.
This procedure will learn the C13567 (C3-Drive) and C45678R (C5 – Reverse) oncoming clutch adapts.
4063779
14-07-30-001C
01.27.2015

 

Holy smokes.......Post #53 above this sounds way to complicated to me. I just want to put the A8 in 'D" and drive away.

I have not experienced any problems with the A8 and hope I never have to figure out the post above. Sounds like you need to be a rocket scientist to figure that out.

 

And most of those that get defensive, claim that everyone that has the slightest little problem, gets on the forum and makes a big deal out of it, thus they claim the problems are over reported.

Here is another A8 transmission replacement that was never reported on this forum(just like my friend never made a single post on this forum about his A8 transmission replacements), but just happened to be mentioned in a post on another topic. Check the member that made post #4 and you will see that he never made a new topic reporting that his A8 was replaced.

Looks to me that the problem is under reported.

https://www.corvetteforum.com/forums...nder-mode.html

Read post #4 and then posts #8 & 9. Talk about heads in the sand.

 

This is going thru the hoops.GM should take care of all this stuff at the factory so when you get in the car everything is done.

 

Who in the hell wants to put up with all that crap. It's an automatic transmission and you should just be able to get into the car, start it, put it in gear, and drive away with out any drama.

It's not just a "performance" transmission that is used only in the Corvette. If you have a Silverado, and you hook up your horse trailer(with two horses on board), do you want all that damn drama, or do you want to get on with your life?

 

Look at the bright side though, at least dealers will get plenty of practice replacing transmissions so they will do it quicker and with less collateral damage.

The second 9 speed auto trans they put in my wife's cherokee at 4,000 miles only took three days (first one took three weeks) and they put all the bolts in the second time

 

Three days!!!!!!

From what I've heard, GM can't make replacement transmissions fast enough to keep up with the demand for replacements

Note that I made an edit to my post you quoted and to look at post #4, not post #2.

 

I agree, just like a all the drama when C6 LS7s dropped a valve