Sugglish transmission shifts

Jim Foreman · February 23, 2020

L83 with 6L80 trans.

After driving for about 2 hours on country roads and through towns, noticed that the trans was shifting differently in town. Caught off guard. After the 2nd time, I checked the temp. 190 which surprised me. Cooled to 181 after I left town.

Repeated in the next town ( sluggish and 190 ) and when finally when I was driving around town at my destination temp got to 192 (and was sluggish).

I had the trans filter changed at 60, 000 and thought I was ahead of the game. Only occasional light towing. Oil level is good.

Have appointment at dealer on Wed. so I don't know if it caused a code or not.

I am trying to do my homework before seeing dealer.

Any ideas?

swathdiver · February 23, 2020

Your transmission has a thermostat so it's temperature will closely mimic your cooling systems. Once you get her back from the dealer, dump that thermostat and consider getting a performance tune from BlackBear. The tune is not so much to make the truck run faster, but to make the transmission perform better and last longer. Did this with mine and the best part of the tune was how the transmission now performs.

Doublebase · February 23, 2020

I think if you had a code it would throw a light on your dash, so I don't think whatever event took place met the parameters to set a code.

I will say that I have the 6 speed and I hate the thing. I absolutely hate it. I have owned many different cars...6 speeds, 8 speeds, 5 speeds. I've never had ANYTHING like this thing. This thing drives around in a state of mass confusion daily, especially in back roads doing 40. Forget about it. And on the highway, now it shutters going up hills, until a mash the gas pedal and cause it to downshift. I have a 2018 with 48,000 miles...bought new less than two years ago. Have done a fluid exchange at 20,000 miles and a pan drop filter replace at 42,000 miles.

I have no doubt in my mind that my transmission will not last past 120,000 miles. I don't tow anything, I don't plow and my daily commute is 90% percent highway at 68 mph. I will be making a decision before I'm out of my power train warranty on whether to sell this thing. Absolutely babied, over maintained, highway driven double cab. Not a single scratch. Babied. It's be a great buy for someone (if you can put up with a confused transmission). I feel your pain.

Donstar · February 23, 2020

19 minutes ago, Doublebase said:

I will say that I have the 6 speed and I hate the thing. I absolutely hate it.

I actually "dislike" any automatic transmission but as manuals are no longer an option.the 6spd is the best, imo. I've owned two 1500's with the 6spd and continue to be pleased. I find it to be a smooth, predictable., and reliable transmission. You may want to take your truck to an objective (not GM) transmission repair facility and see if yours is operating as designed. If it is operating as it should and you haven't made changes like oversized wheels, then look at different techniques. For example, I don't believe "mash the pedal" will send meaningful input to the transmission. Prior to '00 most of my trucks were equipped with a manual transmission. I have grown to appreciate the limitations of an automatic transmissions' brain. It does no good to set high expectations for independence of thought. Give it simple, consistent requests and you will get more consistent and predictable responses.

Doublebase · February 23, 2020

4 hours ago, Donstar said:

I actually "dislike" any automatic transmission but as manuals are no longer an option.the 6spd is the best, imo. I've owned two 1500's with the 6spd and continue to be pleased. I find it to be a smooth, predictable., and reliable transmission. You may want to take your truck to an objective (not GM) transmission repair facility and see if yours is operating as designed. If it is operating as it should and you haven't made changes like oversized wheels, then look at different techniques. For example, I don't believe "mash the pedal" will send meaningful input to the transmission. Prior to '00 most of my trucks were equipped with a manual transmission. I have grown to appreciate the limitations of an automatic transmissions' brain. It does no good to set high expectations for independence of thought. Give it simple, consistent requests and you will get more consistent and predictable responses.

Good to know you’ve had good luck with them. I’m thinking my driving tendencies are perhaps too “easy”. Light throttle, emphasis on fuel economy, stocks wheels and tires, no lift. I’ll keep an eye on it...temps seem fine...fluid looks good, no codes, changed fluid twice already. I suppose I could buy a range device or a tune, but I love the fuel eco of the thing with the V4. I may end up getting a tune after warranty...something that will keep the V4 off during certain speeds...preferably under 40 mph or so. Over that and I find it doesn’t shift as much from gear to gear.

swathdiver · February 25, 2020

On 2/23/2020 at 1:01 PM, Doublebase said:

I think if you had a code it would throw a light on your dash, so I don't think whatever event took place met the parameters to set a code.

I will say that I have the 6 speed and I hate the thing. I absolutely hate it. I have owned many different cars...6 speeds, 8 speeds, 5 speeds. I've never had ANYTHING like this thing. This thing drives around in a state of mass confusion daily, especially in back roads doing 40. Forget about it. And on the highway, now it shutters going up hills, until a mash the gas pedal and cause it to downshift. I have a 2018 with 48,000 miles...bought new less than two years ago. Have done a fluid exchange at 20,000 miles and a pan drop filter replace at 42,000 miles.

I have no doubt in my mind that my transmission will not last past 120,000 miles. I don't tow anything, I don't plow and my daily commute is 90% percent highway at 68 mph. I will be making a decision before I'm out of my power train warranty on whether to sell this thing. Absolutely babied, over maintained, highway driven double cab. Not a single scratch. Babied. It's be a great buy for someone (if you can put up with a confused transmission). I feel your pain.

40 MPH with a 3.42 gear is right around the 5-6 shift depending on tires. Get it tuned and dump the thermostat, then it will last. Your 6L80 is little different than mine and ours seem to last longer.

Grumpy Bear · February 25, 2020

On 2/23/2020 at 12:01 PM, Doublebase said:

I think if you had a code it would throw a light on your dash, so I don't think whatever event took place met the parameters to set a code.

I will say that I have the 6 speed and I hate the thing. I absolutely hate it. I have owned many different cars...6 speeds, 8 speeds, 5 speeds. I've never had ANYTHING like this thing. This thing drives around in a state of mass confusion daily, especially in back roads doing 40. Forget about it. And on the highway, now it shutters going up hills, until a mash the gas pedal and cause it to downshift. I have a 2018 with 48,000 miles...bought new less than two years ago. Have done a fluid exchange at 20,000 miles and a pan drop filter replace at 42,000 miles.

I have no doubt in my mind that my transmission will not last past 120,000 miles. I don't tow anything, I don't plow and my daily commute is 90% percent highway at 68 mph. I will be making a decision before I'm out of my power train warranty on whether to sell this thing. Absolutely babied, over maintained, highway driven double cab. Not a single scratch. Babied. It's be a great buy for someone (if you can put up with a confused transmission). I feel your pain.

Boys at the shop are telling me this stuff works.

I'd also say the thermostat bypass is one of the best things I've done to Pepper. I don't know what the OP means by 'sluggish' shifts. I expect the programmed converter slip/over at each shift. Colder will make it WAY less noticeable.

Mozzer · February 25, 2020

I'd also say the thermostat bypass is one of the best things I've done to Pepper. I don't know what the OP means by 'sluggish' shifts. I expect the programmed converter slip/over at each shift. Colder will make it WAY less noticeable.

Has anyone who lives in an area with cold winters done this. I know the torque converter will not lock up until the fluid reaches 20 deg C.

2014, 5.3, 4x4, work truck

Doublebase · February 25, 2020

3 hours ago, Grumpy Bear said:

Boys at the shop are telling me this stuff works.

I'd also say the thermostat bypass is one of the best things I've done to Pepper. I don't know what the OP means by 'sluggish' shifts. I expect the programmed converter slip/over at each shift. Colder will make it WAY less noticeable.

Probably have to wait till I'm out of power train warranty before I start trying different things. But I'll keep this in mind when I'm at that point.

Doublebase · February 25, 2020

4 hours ago, swathdiver said:

40 MPH with a 3.42 gear is right around the 5-6 shift depending on tires. Get it tuned and dump the thermostat, then it will last. Your 6L80 is little different than mine and ours seem to last longer.

Thanks I'd like a tune that enables me to keep the V4 mode during different speeds...haven't looked in to a tune (figured I'd never need one), but it's looking like I will.

swathdiver · February 25, 2020

4 minutes ago, Doublebase said:

Thanks I'd like a tune that enables me to keep the V4 mode during different speeds...haven't looked in to a tune (figured I'd never need one), but it's looking like I will.

You can certainly do that. When AFM first came out, the Avalanche guys were tweaking AFM with HP Tuners to get 23-25 mpg out of trucks that were lucky to see 18. BlackBear doesn't do this, at least not the last time I asked, but they can certainly improve the performance of the transmission. Just tell them what you want.

Grumpy Bear · February 25, 2020

5 hours ago, Mozzer said:

Has anyone who lives in an area with cold winters done this. I know the torque converter will not lock up until the fluid reaches 20 deg C.

20C is a pretty low bar. Easy to hit.

We hit -35 F (-37C) last winter is that cold enough? Actually I don't drive when it gets that cold. I can offer two years of data with two different thermostats (water). Horizontal line is air temp in F and vertical trans fluid temp in F. Truck speed was 55 MPH a speed I identified as giving the most heat transfer. (50 - 55 mph). As the factory water stat is 207 F and few drive in the zone I do I would expect your actual fluid temperatures to be 30 F higher than these. Or more actually if you have a V8 as your trans cooler is in your hot tank. Mine is in the cold side meaning my numbers are rock bottom. Hope that helps.

As far as automatics go I really like then 6L80E and I've had most of them ever produced.

Edited February 25, 2020 by Grumpy Bear

Grumpy Bear · February 25, 2020

3 hours ago, Doublebase said:

Probably have to wait till I'm out of power train warranty before I start trying different things. But I'll keep this in mind when I'm at that point.

They would have no idea you used that product. It's 2 Oz. Just say' n.

Mozzer · February 28, 2020

20C is a pretty low bar. Easy to hit.

We hit -35 F (-37C) last winter is that cold enough? Actually I don't drive when it gets that cold. I can offer two years of data with two different thermostats (water). Horizontal line is air temp in F and vertical trans fluid temp in F. Truck speed was 55 MPH a speed I identified as giving the most heat transfer. (50 - 55 mph). As the factory water stat is 207 F and few drive in the zone I do I would expect your actual fluid temperatures to be 30 F higher than these. Or more actually if you have a V8 as your trans cooler is in your hot tank. Mine is in the cold side meaning my numbers are rock bottom. Hope that helps.

As far as automatics go I really like then 6L80E and I've had most of them ever produced.

Thanks for the info.

It takes a long while for the transmission temperature to go up anyway (engine temp to normal after 8 minutes driving, transmission temp at 120 fahrenheit after 20 minutes).

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