6.2L 8 Speed OWNERS! GM UPDATE 15389

[440hsp]

I was talking to Higgs boson on here about hp tuners and have been very interested in a tune through diablew if i went the intune route. I know these trucks have a lot of potential. I think I kinda got spoiled though with the 2014 sierra I had. It was a 6.2 6spd 2wd with the 3.42 rearend. That truck right there would roll out. I know i have more weight now with the 4wd but the 3.23 rearend is something to be desired with the 8spd. Once tuners get the 8 spd locked in I'm going for it. Maybe down the road I'll get 3.73's put in it too.

[Higgs Boson]

you can change rear end ratios and tire sizes with the current access. the only thing missing is pressure and shift speed alterations and detailed torque management changes. you can make more sweeping changes as it is now.

 

personally, I wouldn't change the rear ratio anyways. the 8 speed has a 4.56 first gear which is steep. 4.56 X 3.23 = 14.72 the 6L has a 4.02. 14.72/4.02 = 3.66 rear ratio equivalent (which is almost a 3.73). I don't think I would change it unless I went to 35's.

[440hsp]

See higgs, that's why it's good to be on this forum. I don't know how to figure gear ratios and i dont know these transmission specs. Btw higgs, can I get rid of the dang am and governor with the hpt?

[Higgs Boson]

what is the am? you can get rid of speed limiters with HPT. I used to always remove mine but now I just set them to whatever my tires are rated for. sometimes when I am in a sound, rational state of mind I have to save myself from myself for when I am not myself.

[440hsp]

what is the am? you can get rid of speed limiters with HPT. I used to always remove mine but now I just set them to whatever my tires are rated for. sometimes when I am in a sound, rational state of mind I have to save myself from myself for when I am not myself.

Sorry man, meant to say afm mode. Cylinder deactivation. Can you turn that off?

[Higgs Boson]

yes sir

[440hsp]

Awesome

[Jimmyc1182]

I am also having this recall done on Wednesday. There is also a recall to replace the rear U-joint straps and bolts.

[wurgs]

I have to give a shout out to Rob Reierson from Luther GMC in Fargo.

 

I had my truck in for the U-joint bolt recall and my dealer did the TCM update without me even asking. He said he ran my vin just to check it since I had it in and it popped up so he did it. Got to love a service advisor that treats his customers like that!

[sphen22]

Mines in right now for both, 2015 denali 6.2 8 spd, stone blue metallic, was def noticing the clunking at low speeds. Currently at about 8k miles. Will report the difference

[InertiaFaze]

Sorry man, meant to say afm mode. Cylinder deactivation. Can you turn

No AFM in M7 and below.....

[sphen22]

He'd the update done and the u joint bolts replaced, Truck drives a lot better now, especially at low speeds. Shifts are more firm.

[FeelTheThunder]

My truck went in today for an oil change (3300 km's) and they seen the update come up. Flashed the transmission and they said it got worse, they contacted GM and now they need to keep my truck. I just got home with the loaner as Wednesday is Canada Day (holiday) and the transmission guys will get to it on Thursday.

[Rme2513]

you can change rear end ratios and tire sizes with the current access. the only thing missing is pressure and shift speed alterations and detailed torque management changes. you can make more sweeping changes as it is now.

 

personally, I wouldn't change the rear ratio anyways. the 8 speed has a 4.56 first gear which is steep. 4.56 X 3.23 = 14.72 the 6L has a 4.02. 14.72/4.02 = 3.66 rear ratio equivalent (which is almost a 3.73). I don't think I would change it unless I went to 35's.

I am not understanding this I understand the math but that for first gear it looks good but what about the highway gears and towing OD 3.23x.65=2.099 2.099/.67= 3.133 .67 is the overdrive gear for the six speed so that would be a taller gear let go down one gear 3.23x.85= 2.745 2.745x.852= 3.22 so still a taller gear one more time 3.23x1=3.23 3.23x1.152= 2.800 ok let's do this by RPMs my set up is stock. revolution per mile on my tires are 663 so 663x3.23=2141. 2141x.65=1391 rpm at 60 mph let's do the 6 speed with the 3.42s same tire size 3.42x.663=2291. 2291x.67=1534 rpm at 60 mph so I would say it's not almost the same and that for highway speeds and towing is would help to change your gears I would of like to had the 3.42 in my truck with out the max towing package GM is all about the MPGs

[Jordan18]

My truck went in today for an oil change (3300 km's) and they seen the update come up. Flashed the transmission and they said it got worse, they contacted GM and now they need to keep my truck. I just got home with the loaner as Wednesday is Canada Day (holiday) and the transmission guys will get to it on Thursday.

 

You get grief for having oil change at such low KMs? As in was it still free? Mine is at 4700km right now and sitting at 60% and roughly 70 engine hours, I am debating having it changed just to get the factory oil out.

 

I had this update done at around the 3000km mark, mine is still shifting good, just the oddball cold 1-2 shift that seems to be the norm for 8speeds.