I understand just like many this is an old post, but I had my flush supposedly done by the dealer around 10-15k miles and all was well until now that it has 31,600 miles on it and no warranty as it is past the 5yr/60k miles powertrain warranty. It is a 2018 Camaro SS. What advice if any would guys give?

You are going to need to price out torque converter replacement. Maybe the dealer will work with you.

The whole idea of the fluid flush fixing this problem was very dependent on how much uneven wear had already occurred to cause the "shudder." Without question it was cheaper for GM to offer the flush (or multiple flushes) compared to replacing the torque converter. Pray that the customer drives off and has no trouble until out of warranty.

You said right! The bandaid approach is so it holds until out of warranty to get people come back and spend money.

Hi all, got a 2017 Camaro Convt, and Friday after been driving for 6 hours hwy driving and in cruse control in 8th (A8 transmission) gear at 55 MPH on a somewhat level road and saw the Tac moving up then down at 1500/2000 RPM range.

I did feel the car was surging and turned off the cruse and kept as about the same RPM I felt the same.

I am aware of the reported Fluid replacement as a temp fix for some have had done.
1 thing I do is downshift with the paddles to save some wear on the brakes, and maybe this could contribute to the surging/shuttering in the torque converter?

I am now just over 60K but have the GMPP good until 9/28/2024 or 78K, so i'm under that.

I want to do my research before I take it to my GM dealership. I was told to take to a Cadillac dealership over a GM, thinking better support over the GM dealership?

If there is any newer info, please post links..

Thank you!
Christopher

Hi Christopher, the fluid exchange is not a bandaid or a "temp fix" as many claim but the proper solution, provided the TCC (torque converter clutch) friction material hasn't yet degraded beyond a certain point. After that, a torque converter replacement and using the correct fluid to refill is the proper solution.

GM introduced clutch pressure modulation based artificial slip into the transmission tune for the 8L45 and the 8L90, which supposedly improves fuel economy a tiny bit, but depends heavily on the friction coefficient of the transmission fluid. Even a small amount of water absorption reduces this coefficient enough to lead to a continuous slip-grap-slip-grab condition in specific gear/rpm/slip ranges that the driver perceives as "shudder", which gets stronger over time and "creeps" into other gears and rpms as the TCC friction material gradually abrades. The latest Mobil 1 Synthetic LV ATF HP transmission fluid (part number 19417577) is much less hygroscopic than any of the older fluids, so it does not suffer from this problem.

This is also why
1) fluid quality in terms of friction properties is definitely very important in the 8L45/8L90, it isn't the old days of simple slush boxes anymore,
2) the shudder condition depends on moisture content in the air, so it may never (or much, much later) surface in drier climates but may occur very soon and easily in humid states; after all, the tramission and its cooler assembly with the lines isn't a 100% airtight system
3) downshifting doesn't prevent the issue, you just shift out of the "problem zone" for the time being, but over time the trans will start shuddering in 7th gear, too
4) many tune out the programmed slip to say goodbye to this problem for good, but of course that also says goodbye to any powertrain warranty.

I'd visit the dealership ASAP and not try the fluid exchange in my garage, because a proper flush requires their professional equipment. Even if a new torque converter is required, fortunately you still have warranty, so I suggest that you drive 200-250 miles on the new fluid, then if the shudder returns or remains, insist on a TC replacement under warranty.

Hi arpad_m, can I ask how you know of this? I now better understand thanks to you. From what read, the fluid did not fix the shuddering issues and agree driving 500 miles after, will do!

Last Monday I drove 300 miles did not noticed the Tac going up/down or the surging/shuddering effect. I think last year I felt the surging/shuddering but very minor. 3 days later returning home trip about 335 miles 20 miles from home I felt it and noticed the Tac just like the first post with a video. So I think many saying when it warms up can happen right? So it's the "torque converter clutch" causing this and the fluid has more moisture that's causing this surg/shuddering issue?

A few years while I had the car in for service I was aware that the A8 transmission shuddering issue the GM dealer said they found no proof of the issue and would not even do the fluid issue. So I am trying to get the TSB and info to at least replace the fluid, but i'm thinking when they take it for a test drive and it does not surg/shuddering then they will say sorry no issue found so no service. This is what I think will happen, so thinking driving it more will make it worse as I don't want to pay to replace a "torque converter clutch" which I guess that's $2K worth of part and labor? Right?

Thanks again!
Christopher

I learned this from SAE publications (moisture content vs actual friction coefficient of transmission fluids), GM techlink articles, 8L90 videos and specifications, the actual GM transmission tune and other people's posts here. Don't forget that my car also has the 8L90 and I didn't want to have to deal with this problem.

Modern torque converted automatic transmissions have a clutch inside the TC for improved fuel economy (in an attempt to eliminate the power loss due to fluid coupling) that can be and is locked up in certain gears and rpms, as commanded by the transmission tune. Older transmissions relied solely on fluid coupling and exhibited worse power losses.

If you don't get the shudder consistently, your torque converter may still be "salvageable" with the new fluid. The actual wear state of your TCC clutch friction material is impossible to determine without disassembling the trans, that's why you get seemingly so many different outcomes and reports even from dealerships, ie the initial state for each car when the owner starts noticing the shudder or decides to take action is unknown.

You said you had a powertrain warranty, which should cover the entire cost of replacement, parts and labor, whether or not a new torque converter is needed. If that is not the case, your warranty is practically worthless and you could more easily get the car tuned, have the tuner delete the programmed slip plus increase line pressures in the TC and eliminate the shudder this way.

First thank you again! Well after doing some reading on the GMPP ext warranty, they consider Fluids the car owners responsibility and the Fluid flush would not part of the warranty?

So the TSB that was done on this year, would that cover the cost from a GM dealer? My Powertrain was 5 years/60,000 miles which both are past, but the GMPP is good until Sept 2024. but think it's not covered in the GMPP as it's fluids?

As listed in the policy: TRANSMISSION: (Automatic or Standard) Transmission Case and all Internally Lubricated Parts plus: Torque Converter; Flywheel/Flex Plate; Vacuum Modulator; Electronic Shift Control Unit; Transmission Cooler; Transmission Mounts; Oil Pan; Slave/Clutch Master Cylinder; Pilot Bearing; and Throw-Out Bearing.
Also "For maintenance services and parts described in Your Vehicle’s owner’s manual as supplied by the manufacturer and other normal maintenance services and parts which include, but are not limited to: alignments, adjustments, wheel balancing, tune-ups, spark plugs, spark plug wires, glow plugs, hoses, drive belts, brake pads, brake linings/shoes, and wiper blades. Filters, lubricants, coolants, fluids and refrigerants will be covered only
if replacement is required in connection with a Breakdown."

So what is the cost of the fluids for the Surge/shuddering?
Also I have not had the Transmission fluid replaced as I have 61K miles and normally don't replace the fluid, but would not think that would cause this or void the warranty for the current issue?

Again thank you, for helping me..

Christopher

The fluid cost should be between $150 and $200, the TSB calls for 20 quarts (ouch, but it's even worse for the C7 Corvette or the Cadillac CT6 at 24 quarts).

Technically the transmission wouldn't yet need fluid replacement after only 61K miles unless the car is subject to "severe use" meaning mostly stop-and-go city driving, unfortunately this shudder issue complicates things, however. I had two preventive flushes done very early, first with the then-latest fluid, then another time when the correct fluid finally came out in 2019, both under warranty. The dealership was very accommodating, they treated me like a king throughout and never doubted my info or tried to challenge my requests.

The crucial point in your warranty language is what you highlighted, ie whether the shudder is considered a "breakdown" or not. I would argue that it is, because even though the car doesn't die because of it, it the issue results in a compromised drivetrain.

Good luck with the dealership, hope you can get your car fixed properly and never worry about the trans again. Again, if the warranty repair is denied, I would seriously consider a tuning solution (heck, I'd do it no matter what, in fact I did, but I understand different people have different priorities).

Thank you again! You gave me some great info..

Also for the "Tuning" what will this do and what's the Pro & Cons and what kind of shop does this Tuning.

So question, if the GM Dealer will cover it under the GMPP ext warranty, should I take it to a transmission shop to do the fluid replacement or a car repair shop?

I like to have backup plans, I do my own oil change but you said not a DIY in home garage as I think they use a machine to replace the fluid?

So I called the GM dealer and or the other car repairs shops I would ask for a transmission flush or is it called something else?

I would think GM dealership would be $400-$500 to have this done there, but at a car shop $300-$400?

I drove for an hours a few days ago and noticed no issues with Surge/Shuddering, so I want to get this done ASAP..

Thanks again
Christopher

Sorry, I don't really understand the questions about where to take the car. If your warranty covers it, you take it to the dealership's service department and they will take care of you for free. If not, I personally would still use the dealership, because they certainly have the proper equipment, must have done this several times already, and honestly a dealership's name next to a transmission flush looks much better in the service history if you want to sell the car in the future.

Please read the TSB to see what this procedure entails, an independent shop might cut corners and not do it the way GM intended (this isn't an ordinary fluid exchange, it has to be a full flush).

As to tuning pros and cons, a TCM tune can
- optimize the performance of the transmission (make shifts softer/crisper/faster depending on modes and scenarios, just the way you want, though only to an extent since it's obviously still subject to mechanical limitations and basic laws of physics),
- get rid of weirdnesses if any (clunky shifts, jerking, delays etc.), and
- it will certainly prevent the shudder in the future.

The one single, but potentially major, downside is that you will surrender any kind of powertrain warranty for good.