Transmission shudder

It is probably caused by the trucks AFM ability when the truck switches to 4 cylinder mode. Several post concerning GM vehicles with AMF. Many forums reporting transmission shutter and lifter problems. The transmission TSB relating to fluid flush addresses what most report as when accelerating, feels like driving over rumble strips.

My 2019 Corvette has had both.

Only one reply out of over 350 who have read this post. Interesting, thought it was a more common issue. Anyway, I just had the flush and refill with the new Mobil 1 Synthetic and so far have not felt the shudder. Didn't cost anything to have it done at the dealer. Guy said to give it 500 miles worth of driving to give it time to circulate through the transmission really good. If for some reason it should come back he said torque converter replacement would be next step. Said 99 percent of the time flush and fill solves the problem.

Mine had 37k on when I bought it Jan. 2016 Silverado 5.3 with 8 speed. The previous owner had the flush done at 28k. I have 43k on it now. It's been very smooth. I've talked to a lot of people through forums and a few in person who have been very happy with their 8 speeds once the flush was done. And it tows wonderfully, not to mention really good day to day mileage.

There is quirkiness with AFM but I only see it at 45mph and under with a slight vibration. I learned to run in M7 when driving at 45mph or less. No vibration. Locking out AFM eliminates the V4 mode lag. And overall it's even smoother, I no long have wonky downshifts or slams in parking lots.

That’s normally a fluid change. Our Ram truck 8 speeds will hang up in 2nd gear when coming to a stop. Changing the fluid fixes the issue. Anyone that believes in lifetime fluids is asking for a large repair bill. The fluid is expensive, but it’s still cheaper than a trans.

dodge guy wrote:
That’s normally a fluid change. Our Ram truck 8 speeds will hang up in 2nd gear when coming to a stop. Changing the fluid fixes the issue. Anyone that believes in lifetime fluids is asking for a large repair bill. The fluid is expensive, but it’s still cheaper than a trans.

Sorry for the off topic, but...
What are your real world thoughts on the preferred service (drain n fill or complete fluid replacement) on the 8HP70 behind a SRT8?
Car is 5 years old, approaching 40k miles, wife's summer driver, 99% commuter car, 1% husband done a few good burnouts and a couple top speed runs only.
Also is at absolutely necessary to replace the pan? I don't quite understand why that's a single use item.
I'm considering doing a service on it now around 40k miles since the car has been virtually flawless to date and plan is to keep it a long time.

dodge guy wrote:
That’s normally a fluid change. Our Ram truck 8 speeds will hang up in 2nd gear when coming to a stop. Changing the fluid fixes the issue. Anyone that believes in lifetime fluids is asking for a large repair bill. The fluid is expensive, but it’s still cheaper than a trans.

In the case of the GM 8 speed, the 2015-2019 has a TSB for a shudder condition at cruising speeds above 50. The reason is that the transmissions left the factory with the wrong fluid type. It took them until 2019 to figure it out.

https://gm-techlink.com/?p=11127

That said GM maintenance is change of fluid every 45k. Lots of people never follow the engineer's recommendations.

There's a lot of Canyon / Colorado owners with the 8 speed transmission that have the same problem. Fluid change mostly cures the problem, but sometimes the issue comes back.

Grit dog wrote:

dodge guy wrote:
That’s normally a fluid change. Our Ram truck 8 speeds will hang up in 2nd gear when coming to a stop. Changing the fluid fixes the issue. Anyone that believes in lifetime fluids is asking for a large repair bill. The fluid is expensive, but it’s still cheaper than a trans.

Sorry for the off topic, but...
What are your real world thoughts on the preferred service (drain n fill or complete fluid replacement) on the 8HP70 behind a SRT8?
Car is 5 years old, approaching 40k miles, wife's summer driver, 99% commuter car, 1% husband done a few good burnouts and a couple top speed runs only.
Also is at absolutely necessary to replace the pan? I don't quite understand why that's a single use item.
I'm considering doing a service on it now around 40k miles since the car has been virtually flawless to date and plan is to keep it a long time.

Actually I just replaced an 8HP70 in a Tack Hawk. The fluid was black at 37k miles. However I believe the failure was the park solenoid. It was diagnosed by another tech in the shop, and I don’t trust his diagnostics (everything gets replaced type). With that though. I would just do a drain and fill a couple times and it should be good. The filter is built into the trans pan and isn’t cheap, that’s why it’s a one time use pan.But at 40k a drain and fill would be all I would do. Maybe do a filter/pan around 60-70k. They are a good trans, but the fluid is the weak point.

I had the fluid changed in my wife's 2016 GMC 8 speed. It worked on that truck. Had the same thing done on my 2018 ZR2, it didn't solve that problem. I hated that tranny. Put it in reverse and it wouldn't move for like 5 seconds sometimes. Loved the ZR2, pretty awesome little pickup, but that tranny kinda wrecked it for me.

shudder is often friction plates that have absorbed moisture in the fluid. Sometimes, changing fluid will clear it up.