My own 8 speed problems & resolution

Bikemobile · August 30, 2017

11500 miles on my 2017 slt 5.3/8speed. The shifting really smoothed out around 7000 miles. I still get an odd occasional low speed clunk in parking lots and a weird wind up /binding type feeling when accelerating from a stop with the front wheels turned right. Like turning right from a stop sign. It only seems to happen with more agressive throttle application. I think it may be an inelegant torque management feature?

Truck916 · August 30, 2017

My 16 5.3 8 speed denali has 9600 miles. Always shifted nice except for the occasional 1-2 low speed clunk. Had the latest tsb done and it fixed that issue. Tranny is perfect so far.

hotrdlx · September 1, 2017

I just had my torque converter replaced for shutter for the 2nd time. Both time they lasted roughly 16k miles. Does anyone have high miles on their 8sp as i am very concerned about long term reliability. I see now why they decreased the powertrain warranty.

SoonerDPT · September 5, 2017

I just had my torque converter replaced for shutter for the 2nd time. Both time they lasted roughly 16k miles. Does anyone have high miles on their 8sp as i am very concerned about long term reliability. I see now why they decreased the powertrain warranty.

2015 6.2 8speed here. I've got 48,500 miles on my truck and last week the "shudder" just started. It has always had some of the occasional weird clunks when going from park to drive or reverse. Also the occasionally clunky upshifts or downshifts at low speeds. This shudder is new though. I notice it most about 1500-2000 rpms and frequently shudders with upshifts now. Talked to shop foreman this am to get it in and he said "sounds like the torque converter". This thread certainly isn't very encouraging...

MD11G200 · September 6, 2017

Yes very disappointing to confirm my worst fears that I will be plagued with a clunky transmission for life. Has anyone bought and used an aftermarket warranty for this issue beyond the factory warranty? I am looking at buying one and would like some reviews if anyone has any.

AllTerrainX · September 7, 2017

My 16 5.3 8 speed denali has 9600 miles. Always shifted nice except for the occasional 1-2 low speed clunk. Had the latest tsb done and it fixed that issue. Tranny is perfect so far.

Link or number for the TSB?

brendan4862 · September 7, 2017

Wow, I haven't been on here in a while. I was looking at buying a 2017 GMC Denali 6.2 and was wondering if the 8 Speeds had been better. Suffice it to say, they have NOT. I will be steering clear from a 1500. Probably get a 2500HD so I can have a perfected 6 speed again.

I truly feel bad for all you folks that have had issues with the transmissions. I hope this starter brace and TCM update take care of everything.

scott.moody.9401 · September 17, 2017

Link or number for the TSB?

16-NA-411 for the 6.2L, 16-NA-412 for the 5.3

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ponjohn · September 19, 2017

If you saw 2016 8 speed on a lot with only 24k miles, would you immediately think it had trans issues?

Not long enough to be lease return.

scott.moody.9401 · September 20, 2017

If you saw 2016 8 speed on a lot with only 24k miles, would you immediately think it had trans issues?

Not long enough to be lease return.

I'd be very cautious and suspicious. Proceed very carefully lol

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scott.moody.9401 · September 20, 2017

I had the TSB performed on mine and has cured the first shift of the morning issue. Shifts MUCH better.

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maurockstar · September 27, 2017

I've bought yesterday a 2017 1500 Denali. Same problem. Has anyone applied this?

https://gm.oemdtc.com/6777/16-na-019-information-on-transmission-adaptive-functions-and-correcting-low-mileage-harsh-shifts-slips-or-flares-2016-2017-buick-cadillac-chevrolet-gmc/4

JUS1MO · September 28, 2017

Yes, I had mine done at 1500 miles but it did not fix anything. Was told by the service manager to wait until my first oil change and he would fix it. We'll see, at 3800 miles now still doing it.

MY164X4 · October 4, 2017

Are people with 2016 models and the 8 speed transmission having the same issues?

Yes, I recently purchase a used 16 Sierra 8 speed transmission, same issues as others. Still under warranty tomorrow I have a appointment.

Update soon....

MY164X4 · October 7, 2017

Yes, I recently purchase a used 16 Sierra 8 speed transmission, same issues as others. Still under warranty tomorrow I have a appointment.

Update soon....

Went on a drive with the service supervisor as far as the transmission he said mines wasn't that bad, compare to others. I was placed on a list for some type of update.

As far as vibration he said it was my LT tires causing the vibration at 45 mph and 70+ mph.

tires 8/32nds BFG.

This is my first time using LT tires, so I really have no experience how they suppose to ride.