GM 8 Speed Automatic-Lawsuit

[Skippy722]

I thought these 8 and 10 speed auto's were stupid and overcomplicated, until I tried one. You have a gear for everything. No revving or lugging, although i don't mind some revs.

They also improve performance. 2014+ Durangos for example are about a full second faster 0-60 and 50-70 than the 2011-2013 5/6 speed equipped models, despite having the same exact hp and torque and going to a taller final drive (3.45 for 2011-2013 and 3.09 for 2014+ v8’s).

They also avoid that whole “oh… I can do 90mph in 2nd gear…” thing.

 

[buster]

I read that they have done something to the 8L90 valve bodies. The newer 8L45 valve body wiring harness is different. But I haven't been able to find it out what changes specifically were made.

 

[userfriendly]

I really didn't care for the 8 Speed behind the LGX 3.6 in either the CTS or XT5 my family had leased

Rumble stripping sensations, weird shudders, always in the wrong gear

The new 9 Speed is a little better, but I was plenty disappointed with a 2023 XT5 I drove it in

Maybe they've done some stuff to it

Plenty disappointed with the 3.6L LGX and 9 speed in the Cadillac XT5 how?

 

[michaelluscher]

Plenty disappointed with the 3.6L LGX and 9 speed in the Cadillac XT5 how?

The shifts seemed slow and lazy
Yet kickdown was rather abrupt
Maybe it's PCM calibrations and my tastes just didn't get along, but I found it neither luxurious, sporty, or efficient
Kind of a miserable compromise
Sport mode helped, a bit

I know the LGX is a good engine with responsive power, the 2012 SRX Performance we had with the 6 speed automatic was really something else
I was learning to drive around the time we had it, you could hustle that thing along a back road quite nicely, yet reasonable economy
The later models with the 8/9 speeds just don't feel right for me
Maybe it's the ratios? Or the MPG centric shift strategy
But she's leased 6 Cadillacs over the past 20 years, and it seems every one has been a downgrade

 

[LDM]

I have the 8 speed in my 2018 GMC Sierra, only option with the 6.2L. I got it with about 32K miles, after a few months of driving I noticed when cold it would do the hard 1-2 shift. Never had the rumble strip feeling, saw the TSB for the fluid exchange, and had my local dealer do it. I'm at 50K now and I fortunately haven't had any issues with it since then. I know they say that the original fluid absorbed water, which caused the issues, but I also believe that the programming is also the issue. I've seen a number of people who have tuned the transmission and it significantly improved operation for those that were having the worst of the problems.

 

[repairman54]

3.6 in my '20 Traverse w/9 speed shifts just fine. Slow driving with all those gears upshifting is a big change from a 4 or 6 speed.
Hammer down and it's right there. Have a 3.6 Equinox 6 speed also.
Cadoo programming may be different as it's a Cadilac. TCM learns driver patterns also.
Just did a 30k drop and fill in the Traverse with M1 LV HP.
10 speed in my 6.2 Silverado shifts a lot, getting used to extra gears is the big thing in modern vehicles. Especially for an old guy who has cycled through Powerglides, Turbo 350/400 and up through the 4 speeds to now 10 speeds.

 

[buster]

Despite this unit having a long trouble history of TC shudder, it's one of my favorite automatics I've had LOL. It shifts very smoothly and the 3.6L LGZ is a reliable engine. I do get the odd 1-2 shift first thing in the morning. I go slow and once it's shifted for that first time it never happens again.

 

[Strommen95]

The 8 speed was my biggest hesitation buying my 2022 GMC Canyon last year. Especially coming from the ZF 8 Speed. The only complaint I have so far is very minor. When it's cool out(lower 50's or below) the first shift is rough if not warmed up. Other than that, it shifts very smoothly and is always in the right gear. Pretty much exactly as buster said.

Given it's been out for a while though, the tranny certainly should be cleaned up by this point in time.

 

[Dave1027]

My old f350 has a clutch as god intended

When I'm pulling my boat on a tricky launch ramp, I thank God I have an automatic.

 

[ctechbob]

TCM learns driver patterns also.

Not to be pedantic, but this keeps getting repeated about many different transmissions and it is just wrong.

Adaptive learning in transmissions are for learning how the transmission is working internally and adapting to differences in clutch fill times, apply rates, clutch slippage, etc. It isn't about learning anyone's driving style regardless of what a salesperson (or that clown FordBossMe) might tell you.

This is why all manufacturers have a very specific relearn procedure that you're supposed to follow when you wipe the adaptive tables, specifically to take the driver OUT of the relearn procedure.

 

[nascarnation]

Not to be pedantic, but this keeps getting repeated about many different transmissions and it is just wrong.

Adaptive learning in transmissions are for learning how the transmission is working internally and adapting to differences in clutch fill times, apply rates, clutch slippage, etc. It isn't about learning anyone's driving style regardless of what a salesperson (or that clown FordBossMe) might tell you.

This is why all manufacturers have a very specific relearn procedure that you're supposed to follow when you wipe the adaptive tables, specifically to take the driver OUT of the relearn procedure.

It's nice to see a post by someone who actually understands the process.