[ANSWERED] C7 A8 Transmission and Torque Convertor Questions
 

Original question is here.

Good to hear issues with the A8 are very rare.

So...

What exact changes were made to the TC?

Bah.

BTW: if there's any doubt left in anyone's mind that Tadge enjoys this interaction - The answer was sent to me today while he's on vacation in some place fairly nice (from what I've been told) and warm. And it was also worked on while he was on business travel to and from Geneva for the GS announcement last week.

(Question 2) (The service bulletin you cite says to perform a double oil flush if you suspect that the trans is exhibiting TCC (torque converter clutch) shudder. That procedure has been successful in fixing a few vehicles. This has primarily been a truck issue, pretty rare on Corvette. The bulletin is now being updated to have the converters replaced instead of just a flush since it has not been 100% effective. So the bottom line is if customers are not having any problems, they shouldn’t worry about that document. In the rare instance where there is truly a torque converter problem, there is new design that should help. That hardware became available in December of 2015. I want to make sure customers with the prior design understand that if there is an issue, symptoms will appear early in the car’s life. The design change was not to improve the performance of the car or it’s durability over the long term. Bottom line is that if customers are not having a problem now, it is very unlikely to occur later.)


This statement says that there is a problem that flushing does not fix and the tc's are being replaced. Then at the end the statement says it is not to improve performance or durability. This appears to be a contradiction because shudder and shake and hard shifts are definitely a performance issue.

I believe Tadge is saying there is no performance improvement compared to a normally operating older version. As in, no difference in shift quality, speed, firmness, etc. Of course there's a "performance improvement" compared to one not functioning properly.

tcc shudder
 

The problem is isolated to the convertor clutch only. It could be anything that cause it. The bulletin implies that it is a characteristic of the wear of the clutch. If the clutch develops a shudder as it wears that the tcc solenoid can not compensate for , then the convertor requires replacement.

Would anyone dare to speculate as to when the dealerships will be aware of this information?

I daily drive my Corvette and am quite anxious to get this problem resolved. :willy:

Question 1} Part number 24274892 was released for use with the heavy duty cooling option which comes with Z51 and Z06 automatics (and will be for the just-introduced 2017 Grand Sport}. The transmission hardware itself is the same as the prior part number (24273222). The difference is that it contains more oil in it to compensate for the extra coolers and cooler line volume added to the vehicle. The 24273222 trans assembly remains released for use with the standard LT1 cooling package. The break-point for the new part number in Bowling Green was May of 2015.

I take "standard LT1 cooling package" to mean non-Z51 & non-Z06 - in other words, the wet sump motor.

So, in essence, the new part number ...4892 is the same tranny that goes with wet & dry sump motors, but with more (oil) cooling capacity if a dry sump motor?

If you have a wet sump motor, the May 2015 date is meaningless - wet sumps continued to get the same tranny (part number ...3222) whether produced before or after May 2015.

Did I interpret this correctly?

The Torque Converter is being replaced on my A8 after Sebring Corvette Corral. All it took was for the service manager to verify problem after sitting two hours. Has to be cold to occur on my car. Thanks for stepping up GM.

Does anyone have a copy of the bulletin: 4373638? I'm curious to see what it says. I'm purchasing a car that was built in December so I'm slightly nervous about this. Especially since my local dealer here said they've never heard of this.

Thanks

I had the harsh 1-2 shift issue and both of the larger dealerships I called here in Florida were aware of the problem and had done TCC replacements.

I took my car in a month ago, TCC replaced, problem fixed

So my Z51 was built December 6th. Do I have the new or old TC?

Based on Tadge's response I say you have the new t/c :thumbs:

I really wish I had added this to Question#2 to Tadge.

Does switching out of V8 mode to V4 mode have anything to do with TCC (torque converter clutch) shudder?

Please reply with the name and location of the dealer that did the repair. I am getting the "we never heard of this" response from my dealer in Texas. I would like your dealer info so I can have my dealer contact your dealer and get educated on the first to second abrupt shift issue. Appreciate any help you can provide.

Try Sunset Chevrolet in Sarasota FL, shop foreman Bob Wiseman 941 366 7800. First effort will be to reprogram TCM. If that does not work most likely converter part #24279495 may need to be replaced with same part # but now version 4.115 I recall the new version comes from a supplier in Detroit.

Also try Stingray Corvette near Plant city FL.

The harsh 1-2 shift after extended sitting ( overnight) is caused by fluid bleeding back from some TC's . After a couple of shifts first drive of the day the TC is now pressurized so shifts are now smooth.

Hope that helps.......good luck and post results when fixed ...tks

Yes. It is only an issue with dry sump motors.

No. I had the service manager experience the problem while watching the V4 and V8 mode, It has nothing to do with it. Lunging when cold was evident very early on the car. The shudder at constant speed problem did not appear until 10K miles. Everything resolved when TC and Trans was replaced. Now service mgr tells me the current repair is replacement of TC only.