My own 8 speed problems & resolution

[Black02Silverado]

2 hours ago, wlezel said:

Do you have a link to this? I’d like to check it out!

GM Authority 2019 Silverado 8sp enhanced

[Mileguru]

Just now, huntr1117 said:

What tcm did you use? What was the doner vehicle?

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Blackbear sold me a 2015 TCM (The 2015 part # is 24274896) way back when. I don't know the donor vehicle it came from.

[Mileguru]

49 minutes ago, Black02Silverado said:

GM Authority 2019 Silverado 8sp enhanced

But I thought the 14-17 8-speeds were "operating within specs" and everything was "normal." <<Sarcasm, of course>>

[Mileguru]

14 minutes ago, huntr1117 said:

What tcm did you use? What was the doner vehicle?

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Picture of the 2015 TCM.

 

[Black02Silverado]

7 minutes ago, Mileguru said:

But I thought the 14-17 8-speeds were "operating within specs" and everything was "normal."

To me, if you can really feel any part of a transmission shifting other than some up shifts during WOT then to me it isn't operating like it should.  Transmission in the past have been smooth, why are they not today?  Mine shifts hard, but I have it programed that way on purpose. Also i can't feel it downshift at all and you shouldn't. 

 

This update is telling me that GM knows there is an issue and they are trying to make sure it doesn't put a dark light on their brand new baby that comes out this fall.

[huntr1117]

Picture of the 2015 TCM.
 

My spare tcm is also a T87, but the part # is 24276411. They said to get that part # it was one of two that would work. That's the only part # they told me. They also said that it had to be from a truck with a 6.2 8 speed. I just emailed them. Hopefully the process will work on mine and that I didnt buy a spare tcm for nothing.



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[Mileguru]

37 minutes ago, Black02Silverado said:

To me, if you can really feel any part of a transmission shifting other than some up shifts during WOT then to me it isn't operating like it should.  Transmission in the past have been smooth, why are they not today?  Mine shifts hard, but I have it programed that way on purpose. Also i can't feel it downshift at all and you shouldn't. 

 

This update is telling me that GM knows there is an issue and they are trying to make sure it doesn't put a dark light on their brand new baby that comes out this fall.

I totally agree.

[Mileguru]

40 minutes ago, huntr1117 said:

My spare tcm is also a T87, but the part # is 24276411. They said to get that part # it was one of two that would work. That's the only part # they told me. They also said that it had to be from a truck with a 6.2 8 speed. I just emailed them. Hopefully the process will work on mine and that I didnt buy a spare tcm for nothing.



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T87 is the TCM for 2016 and below.

T87A is the TCM for the 2017+.

 

Part # for 2015 TCM is 24274896

Part # for 2016 TCM is 24276411

Part # for 2017 TCM is 24279973

 

Blackbear told you to try and match the vehicle as closely as possible because of what happened with me (Sierra 5.3 8-speed with Sierra 5.3 8-speed, Yukon 6.2L 8-speed with Yukon 6.2L 8-speed, etc.)

[MD11G200]

I’m still having problems with my 6.2/ 8 speed and can’t tell from this post whether or not 2 things- 1 are people getting relief from clunky transmissions with a flush?? Not sure how that helps- didn’t work for mine

2- will black bear tune work or not ? That topic is all over the place with no solid answer

[Mileguru]

2 hours ago, MD11G200 said:

I’m still having problems with my 6.2/ 8 speed and can’t tell from this post whether or not 2 things- 1 are people getting relief from clunky transmissions with a flush?? Not sure how that helps- didn’t work for mine

2- will black bear tune work or not ? That topic is all over the place with no solid answer

I can't answer your first question, but your second question is clearly answered in a post I made on the previous page.

 

2016 and below, anyone can tune the 8-speed via any tuning software you want to use (Autocal or HPT).

2017 and above, only Trifecta can tune the TCM without having to remove it. HPT can be used to tune it if you send it to them first. BlackBear claims to have been able to swap a 2014-2015 TCM in place of your 2017 TCM. They have stated that it has worked in some cases and not others.

[BlackBearPerf]

On 7/22/2018 at 2:27 PM, Mileguru said:

I can't answer your first question, but your second question is clearly answered in a post I made on the previous page.

 

2016 and below, anyone can tune the 8-speed via any tuning software you want to use (Autocal or HPT).

2017 and above, only Trifecta can tune the TCM without having to remove it. HPT can be used to tune it if you send it to them first. BlackBear claims to have been able to swap a 2014-2015 TCM in place of your 2017 TCM. They have stated that it has worked in some cases and not others.

That is correct.  Our solution did not work out for some of our customers, as a result we just offer engine only tuning with our AutoCal on the 2017+ 8 speed, and engine and transmission tuning on the 2017+ 6 speeds. 

[BlackBearPerf]

On 7/22/2018 at 12:04 PM, MD11G200 said:

I’m still having problems with my 6.2/ 8 speed and can’t tell from this post whether or not 2 things- 1 are people getting relief from clunky transmissions with a flush?? Not sure how that helps- didn’t work for mine

2- will black bear tune work or not ? That topic is all over the place with no solid answer

Our solution did not work out for some of our customers, as a result we just offer engine only tuning with our AutoCal on the 2017+ 8 speed, and engine and transmission tuning on the 2017+ 6 speeds. 

[wlezel]

@BlackBearPerf In your honest opinion, how effective is the 'engine only' tune compared to a engine/tranny both tune? Just curious if it's truly worth it to only tune the engine.. aka how much of a loss is it not having the tranny tuned as well? 

 

2017 GMC Sierra 6.2/8speed owner

[BlackBearPerf]

1 minute ago, wlezel said:

@BlackBearPerf In your honest opinion, how effective is the 'engine only' tune compared to a engine/tranny both tune? Just curious if it's truly worth it to only tune the engine.. aka how much of a loss is it not having the tranny tuned as well? 

 

2017 GMC Sierra 6.2/8speed owner

You will still see HP and TQ improvements, along with improved throttle response. If you have no issues with the shifting, transmission, then the engine only tune would be beneficial. 

[MD11G200]

Maybe I didn’t see were someone  posted the price for the blackbear tune but it’s $599 and offers a low and high octane tune, that ain’t worth it for engine only in my opinion, I called after the post on here to confirm. My  truck goes to the third dealership next week(one I purchased  it from 3 hours away) a trade is in my future. Have had a chance to drive several 5.3 6 speed Chevrolet trucks and suburbans- transmissions smooth as glass, pisses my off because GM knows the 8 speeds ain’t right and refuses to fix there TCM