Had to replace flywheel on my new 2016 coupe with only 913 miles. Obviously this a problem since GM issued a bulletin #15-NA-045.Coupe is an automatic.Has anyone encountered this situation?

 

Recall several posts some time ago for 2014's that springs were missing from the dual mass flywheel. Don't recall any lately.

 

Our 2014 had the same problem and it appears the great GM has not corrected the problem after 3 years of production. The unlucky ones are so few and far between that is cheaper to fix the problem than correct it. I hope this isn't the start of your problems because that is what happened with us when the dash started acting up.

 

Friend with a 2015 Z06 A8 has a pretty bad rattle coming from the bellhousing area. I think his flexplate is bad. He doesn't have very many miles on it.

 

OP has the automatic with a flexplate(not a flywheel).

 

My 2016 coupe with 4000 miles is getting the flex plate replaced next week. Rattling sound only at idle.

 

That's awful. Where can I find GM TSBs??

 

I'm not sure there is a TSB for this issue but if you search for flex plate on Z06 forum you will see some Flex plate issues

 

My Bad! Just saw flywheel so assumed that is what he had, should have read further and noted he had an automatic so doesn't have a flywheel!

 

I am heading to Chevrolet dealer today to confirm diagnosis for my 2014 C7 Z51 AT @ 58K miles. Based on symptoms, most likely only flex plate is bad. My car is "half way" out of warranty, time limit expired, but milage is still under the limit, so GM agreed to cover the cost, if diagnosis is confirmed by the dealer.

Apparently, things never got any better as GM issued yet another TSB # 18-NA-268 on June, 2019, and it now includes additional issue with front bearing shift caused by drive shaft couplers failure.

Warning: 2014-2015 owners! Your cars are about to start dropping from powertrain warranty (5 years/60,000m), make sure you do not have this issue as inspection to diagnose this issue is very simple, but if you lapse on warranty - you will be up for a large out of pocket expense!

Subject: Rattle Noise Heard from Front of Vehicle When Engine is Running at Slower Speeds

Brand: Chevrolet
Model: Corvette
Model Year From: 2014
Model Year To: 2019
VIN: NA
Engine: 6.2L (LT1, LT4)
Transmission: 6L80, 8L90 Automatic (MYC, M5U)

Condition
Some customers may comment that they hear a rattle noise coming from the front of the vehicle when the engine is running at slower engine speeds.

Cause
This condition may be caused by a deformed propshaft rubber coupler, which may move the driveline support assembly’s front input shaft bearing out of position.

Correction
Note: Do Not replace the Driveline Support Assembly (DSA) for a recessed bearing. Replacing the complete DSA will no longer be recommended.
If a noise was confirmed to be coming from the rear of the engine area, perform the following steps in the Service Procedure below.

...

Here is the link: https://static.nhtsa.gov/odi/tsbs/20...63229-9999.pdf

 

Lol, GM refused to cover repair excusing themselves with following: "Due to the lack of maintenance on your vehicle, there is no cost assistance that we can provide you. There was no maintenance documentation related on your vehicle for the past 4 years. This is a high performance vehicle that needs to be maintained to insure proper longevity."

But this is where all fun begins, I got the part and with help of my son, we started disassembly process to get to this Flex Plate. I needed to loosen the lock bolt on the plate hub to free the drive shaft for removal and then just out of curiosity popped the inspection cover on the transmission end of the torque tube and WFT?!? The rear flex plate attached to the torque converter freely rotates ~ 60 degrees. At this point, there was very little doubt the problem is with the drive shaft and not with the Flex Pate on the crankshaft. It was a good news, because of replacing front Flex Plate is more involved as it requires to drop engine with subframe by 25mm to get to the bell house bolts on the top - Thanks, but no thanks!

Interesting fact - GM asked me to bring car for diagnostic and technician looked at the car to diagnose the issue - he never even bothered to check the transmission end, so he just put Flex Plate as cause of the issue. What kind of technicians GM is hiring? BTW, the front drive shaft bearing was not recessed and looked very normal. Anyway, I was expecting GM technicians to be a bit more proficient and do their due diligence while at work.

DIY, is not simple as there is no video or any info on the forums for C7 and mine has Z51 that complicates things even more with electronic differential lock. We only used GM Service Instructions for torque figures, most of the process described is idiotic endless disassembly of just about everything there is there to take apart. Installation instructions were even worse as they would cause potential damage to engine thrust bearings, if you follow those. Simple rule - you should not force driveshaft into hub, following instructions will make you do exactly that, so you have to think out of the box about how to alter process to get everything to join without "brutal" force.

First time is difficult, but when you know the "easy" way it is not bad at all, just tedious.

We are still puzzled how this could have happened, we purchased car with 40K miles on odometer. Initially we thought some strange sounds is part of corvette experience, but those became real bad after +20K miles. The bearings are fine though, only dampers should be replaced and it will be a nice backup. We swapped torque tube with used one from eBay we got just in case we need one during repair.

 

On second thought, I am glad the dealer was not involved in changing it, because of they most likely would "force" shaft into flex wheel hub by following dumb GM service instructions and cause damage to engine and shaft. Some unlucky folks who had issue with drive shaft, ended up with in some cases with 3, 4 times shaft replacements that ended up with damaged engine fiasco. So, yes it would be nice for GM to fix it, but a 1000 miles later I might regret it big time. As my car is out of warranty I should not take this bargain even if GM would offer to cover the cost.

Usually, the shaft bearings are busted, but in my case, bearings survived and the only thing needed was new couplers, but there is no way to purchase it. RMP Transmission would sell it to you with phone order for ridiculous price of $200 each. So at $400 a pair - it makes repair not economical, because of you can get brand new drive shaft from GM for ~$1000 with 1 -year warranty and do not bother with old shaft at all, just return it for core refund of $400, that makes final price of $600:
PN 19302510 - Drive Shaft - Without z06. Manual trans
PN 23366290 - Drive Shaft - Auto trans. Without z06. With z06, grand sport.

C7 coupler size:
Number of bolts - 6 M12x1.5
Bolt hole diameter - 12.05 mm
Bolt pattern diameter - 78mm
Sleeve length - 35mm
Bolt mount length - 38.45 mm

the coupler has 007835.1 printed on it.

I passed this information to Dorman - so may be they will start making those couplers and sell it at more reasonable price of ~$60, like they do for older Corvettes.

Be safe, and enjoy your Corvette.

I found this photo of the slightly damaged coupler on this forum, as mine were mutilated completely.

 

Wanted to post on here too. Just got my 19 Stingray back after a week at the dealer. I picked the car up n March of 18. 24K miles on it. Couple months ago. I heard a rattling sound which I thought may have been exhaust related due to aftermarket x-pipe being installed the previous fall. I took the car in and they could feel the sound resonating through the x-pipe. I got my stock pipe from home and they swapped out the pipes, which did not eliminate the sound. They started to go further in to check the torque tube. Rear yoke on the propshaft was loose. They replaced the torque tube and flexplate per the bulletin. The flexplate they replaced it with is from the LT4.

 

10K miles later and used torque tube (had 60K when we bought it) failed as well. We never disassembled it to verify condition of the propeller shaft. Apparently, it was going the same way ours went. This time we purchased new propeller shaft from the GM PN: 23366290 with warranty and just assembled it to our original torque tube from the first swap. Will see how long it would last. Second replacement was a way easier, as we knew how-to do it "the right way".

Torque Tube - failed

 

That statement from GM is crazy! I'll explain how I got a replacement Differential covered 2 months AFTER the Warranty had expired. Was a bit of work BUT as I got my first new car, a 1967 Chevy's cracked clutch plate covered and a hole in my C6 AC Condenser covered I did something similar! BTW both Chevys were about 6 months old BUT warranty initially denied because; 1) a clutch is a wear part (but not for an obvious defect in the casting) and wrote a report with pics showing that Condenser hole was not caused by a rock!

First the Dif issue was NOT in a Chevy, it was my 260Z Datsun (as they called themselves back in the day in the US!)
I had downshifted going into a fast a turn and heard a noise that sounded like a jet plan was overhead. But as I slowed so did the noise. Got out, looked under the rear and the fluid was draining from the Dif cover! Drove the car ~3 miles back to my home very slowly. Crawled under after jacking it up and there was a hole in the diff case about the size of a dime! Had it towed to the Datsun Dealer. They said yep, you'll need a new Dif! Heck paid $1200 and in 1974 the car only cost ~$5000 new! Took the old Dif home and when I removed the cover (which the dealer never did) found one bolt on the ring gear had come lose, worked it's way out and sheared on the case. Could see where it hit! The bolt head sheared off and like a bullet put a hole in the case from the inside!

Then the key that got the new Dif paid for! The Datsun Service Manual, which I bought (like the 4 volume Service Manual I had for my 2014 Z51) had this to say about the locking tabs that are on all ring bolts in pairs. "IF THE DIFFERENTIAL COVER IS OFF, CHECK TO SEE THAT ALL SAFETY TABS ARE BENT OVER TO RETAIN THE BOLTS!"

However no where in the Service Manual did it ever say to remove the Dif cover for Maintenance! In addition the Dif sat in a rear cross member and in order to get the cover off the Dif had to be lowered! Since I was managing an R&D Lab involving welding material development we had a Metallurgical Lab. Took macro pictures of the Bolt head and showed it was a very ductile failure. Also took Macro pics of the ring and pinion gears showing they were perfect and there was no wear from abuse. In fact had the dealer removed the cover they could have replaced the bolt, bent the Safety Locking Tab properly and just put on a new cover! Wrote a report with pics and said the obvious cause was the Safety Locking Tab was not bent up to prevent the bolt from loosening (also took that pic.) The Dealer did not want to hear the argument. Wrote to Datsun US. Got a letter back that said sorry!

So since one of my Laboratory Division Head's was Japanese, had him hand write a cover note in Japanese and attached it to the report that said we have done and analysis and found the warning in your Service Manual is correct BUT we never had reason to remove the Dif cover and your Service Manual does not indicate that is every required for maintenance. It was mailed to the President of Nissan Japan!

He ended with the typical US Litigious Society comment. Nissan is fortunate the car was not on a highway and been in an incident causing injury.

Dealer was instructed to give my $1200 back!

How can GM say anything about lack of maintenance causing a problem where there is no scheduled maintenance for a flexplate or driveshaft?! Changing engine oil, filter, flushing brake or cooling fluid etc has nothing to do with a flexplate of drivshaft! Now if you have headers or other power adders they might have an argument- although week.

Frankly I'd try a nicely worded letter, ask for at least the money you have paid for parts and end with, "Hope I Do Not Have to Consult an Attorney!

 

Just for info: When there is any tiny play in flex plate, hub or bearing to tube body - there will be noise associated with the source. Following service manual you suppose to hand tighten flexplate hub clamp before first engine start to get through temperature cycle. Hub to shaft interface was rattling so annoying (there is a free play by design to allow assembly/disassembly) - we have to stop cycle and tighten clamp more securely to stop the rattle during this step and perform final torque for the clamp. The back of the driveshaft assembly is not super tight either to allow disassembly/assembly, so it can make small ticking sound at idle. The front bearing is not super tight for the same reasons, but there is a small rubber ring damper there to cut any noise.