[ajp]

Many moons ago I read that the Range device keeps the shudder at bay.

Any truth to that?

[cellsafemode]

there is no truth to that.

AFM has nothing to do with the transmission. V4 and V8 and V6 modes all happen in the engine and the tcm behavior doesn't change at all based on the afm mode of the engine as far as i know.

What might lead people to thinking that besides just blindly thinking afm == bad so everything bad is caused by afm is that the TCC shudder occurs at low engine load most relevantly and this also coincides with when afm kicks in.

However, it's the engine load that leads to tcc shudder being noticeable and this can happen in any afm mode.

Water content in the fluid is what I thought GM finally determined was the cause. Tuning the transmission may delay the effect by increasing line pressure, but eventually watery trans fluid will lead to shudder even then. (my trans has been tuned since mid 2016 and it started getting a shudder after 35k miles a few months ago and i can turn V4 mode on and off at will and the effect was there with afm disabled)

If you leave it go too long you'll get perm damage to the tcc.

If you have hard shifts at 1-2 gear they recommend a tcm tune to address that ...but that's a separate issue from tcc shudder.

[HCI2000SS]

While the latest fluid and flush procedure "seams" to be the fix, I personally don't have have strong faith in this trans and/or torque converter. I guess the real question becomes weather it will last the duration of the ownership. Most modern cars that I've driven don't have the quirky traits of this GM A8... shudder aside. From the occasional hard 1-2 shift, to the odd hunting of gears (and not dropping to right one sometimes under WOT) etc... Hopefully I'm wrong, and this trans and converter will last as long as any proper setup, but I just feel feel there's just something not right with this setup. Time will tell

[Need4Camaro]

Well I got my SS back.

I am EVER so glad I decided to keep my extended warranty as I knew this car would give me trouble in the future. They replaced the converter and all the fluid.
The job normally costs about $2,700. I paid $370.
Everything works as it should for now.

Originally Posted by HCI2000SS

While the latest fluid and flush procedure "seams" to be the fix, I personally don't have have strong faith in this trans and/or torque converter. I guess the real question becomes weather it will last the duration of the ownership. Most modern cars that I've driven don't have the quirky traits of this GM A8... shudder aside. From the occasional hard 1-2 shift, to the odd hunting of gears (and not dropping to right one sometimes under WOT) etc... Hopefully I'm wrong, and this trans and converter will last as long as any proper setup, but I just feel feel there's just something not right with this setup. Time will tell

Honestly I’m worried about that too. This would have been a bullet wound had I not have had my extended warranty and the fact that it happened literally 1k miles out of warranty would have just been GM smiting me.

The harsh 1st / 2nd shift can be fixed in the tune. GM fixed that for me on my previous 6th Gen. I’m mostly worried about the TC though. I’m going to see about getting my car tuned to prevent this from happening in the future.

[cellsafemode]

2700 bucks is a crazy amount of money for 100 bucks worth of fluid and a 300 dollar tcc.

There is a transmission learn mode you can put your trans into the relearn the solenoids and clutches that can solve certain shifting symptoms you might want to try before tuning.

https://static.nhtsa.gov/odi/tsbs/20...66092-9133.pdf

[classicrockr]

Originally Posted by Need4Camaro

Well I got my SS back.

I am EVER so glad I decided to keep my extended warranty as I knew this car would give me trouble in the future. They replaced the converter and all the fluid.
The job normally costs about $2,700. I paid $370.
Everything works as it should for now.

Honestly I’m worried about that too. This would have been a bullet wound had I not have had my extended warranty and the fact that it happened literally 1k miles out of warranty would have just been GM smiting me.

The harsh 1st / 2nd shift can be fixed in the tune. GM fixed that for me on my previous 6th Gen. I’m mostly worried about the TC though. I’m going to see about getting my car tuned to prevent this from happening in the future.

Glad to see the extended warranty covered it. Im taking mine in under extended warranty tomorrow

[PHLCamaro]

I have had the new flush twice in my car, the first time the car actually drove worse post-flush. The second time, it got better, but the issue is still there. Have the car in the shop today and the dealership just called to say "we cannot replicate the problem." I argued and they will be driving it more.


I have no faith in this car or the ability to get this solved under warranty. It's really frustrating, and while I absolutely love this problem, I have two problems with this car that I cannot seem to get resolved. I'm close to giving up. The car is no fun to drive with two issues.

[classicrockr]

Finally got a dealer to agree that its the TC issue. They told me that if theres no metal shavings in the fluid, then the fluid change isnt covered under the extended warranty; only way its covered is if the TC has to be replaced

[Dagstar]

Originally Posted by PHLCamaro

I have had the new flush twice in my car, the first time the car actually drove worse post-flush. The second time, it got better, but the issue is still there. Have the car in the shop today and the dealership just called to say "we cannot replicate the problem." I argued and they will be driving it more.

Mine was the same way after the first flush. The second flush using the new fluid (it had just come out) fixed it. I rode along with the same tech on both test drives. I'd insist on that. It shouldn't take much to replicate the shudder.

[Joshinator99]

Originally Posted by cellsafemode

there is no truth to that.

AFM has nothing to do with the transmission. V4 and V8 and V6 modes all happen in the engine and the tcm behavior doesn't change at all based on the afm mode of the engine as far as i know.

This is incorrect. The TCM is programmed to slip the TC during AFM operation.

[cellsafemode]

Originally Posted by Joshinator99

This is incorrect. The TCM is programmed to slip the TC during AFM operation.

I read the patent, The tcc slip is calculated all the time and does react to cylinder deactivation. However it's purpose is just to react to changing vibrations and harmonics in the engine from different firing sequences.

So yeah, the trans does appear to react to changing active cylinders. But I don't see how changing slip during v4 is going to impact the commanded slip while not in v4 mode where this issue occurs

[Joshinator99]

Originally Posted by cellsafemode

I read the patent, The tcc slip is calculated all the time and does react to cylinder deactivation. However it's purpose is just to react to changing vibrations and harmonics in the engine from different firing sequences.

So yeah, the trans does appear to react to changing active cylinders. But I don't see how changing slip during v4 is going to impact the commanded slip while not in v4 mode where this issue occurs

The slip increases during AFM to compensate for V4 operation as you alluded to. Ditching AFM means less TC slip, which is a good thing. I zeroed all my TCC tables almost immediately after buying my car new, have never had any shudder. But with only 6500 miles on my car, it’s not really a great example.

[cellsafemode]

Originally Posted by Joshinator99

The slip increases during AFM to compensate for V4 operation as you alluded to. Ditching AFM means less TC slip, which is a good thing. I zeroed all my TCC tables almost immediately after buying my car new, have never had any shudder. But with only 6500 miles on my car, it’s not really a great example.

i've had my tcm reprogrammed since 2016. I can control when I allow v4 mode or not and I mostly stick to not just out of habit unless i'm taking a longish road trip. Still ended up with the beginning of tcc shudder after 35k.

The shudder is caused by water in the fluid that occurs because the fluid that came stock before the 1st quarter of 2019 liked attracting water. The cars (ss and 1le, zl1) all have extra trans coolers that tend to keep the fluid from ever reaching high temps that would expel the water. This makes the trans fluid too slippery. on top of that, the water will periodically boil in the tcc due to this and varnish coat the tcc ...which exasperates the problem and it becomes a permanent issue requiring tcc replacement.

The slip programming wont save you. It's just a matter of time and the specific environment and avg trans temp. If you're using fluid from before the 1st quarter of 2019, you will eventually develop the issue unless you're really lucky.

the base lt (v6 and i4) dont get the extra trans coolers, so our fluid stays higher in the 180+ range most of the time except long distance cruises. So those cars will see the issue less, but they're not safe from it. And I've been running practically since the car was purchased with a tune that increases trans line pressure, makes afm user selectable, live in a place that never gets cold or wet and all that and it still developed it after 4.5 years and 35k miles.


luckily, i felt it in the pedal before it got bad enough to be something you feel in the whole car. Fluid change to the new blue label stuff (and i dropped the pan to clean out the sludge and change the filter since it was a 1st time trans flush) and everything is good as new. If you get it and wait too long, you'll need to replace the tcc as well.

It's strongly recommended that you change your fluid to the new blue label stuff, even if you dont have the shudder. there's 0 sense in waiting for the problem to manifest.

[PHLCamaro]

Originally Posted by Dagstar

Mine was the same way after the first flush. The second flush using the new fluid (it had just come out) fixed it. I rode along with the same tech on both test drives. I'd insist on that. It shouldn't take much to replicate the shudder.

Yeah, I tried that and they are basically refusing. This dealership clearly has no interest in helping me, they are ignoring this and a very obvious second problem (rear of car clunks on hard downshift during braking or when accelerating from previously coasting). I'm going to find a new one, someone DM'ed me a suggestion that's a bit far but it may be the way to go.


I'm just very frustrated with both how GM is handling this and my experience with the dealership. It makes me regret buying a Chevy, and this is my favorite car I've ever owned, but a car with the miles I have just should not drive this poorly. Especially when people drive these cars for the driving experience. When I bought this car I intended to keep it until the wheels fell off, but now I'm already thinking of dumping it before the warranty runs out.