Piston Slap: Seeking a “Professional Grade” GM Transmission
Steve writes:
Is there a cure to the hesitation in first gear that Canyon and Colorado eight-speed transmissions experience? I get a “kick in the pants” during rolling stops for the first few minutes that my 2018 Canyon runs. Then it disappears ’till the next start.
Sajeev answers:
(EDIT: In the comments below, it appears that the first place to look is at the transmission fluid, as its a well known fact that this issue can be addressed with a change to a different fluid. So my revised answer is to visit the dealership or a trusted repair shop and ask for their opinion on your vehicle specifically.)
It’s a good thing Piston Slap is a weekly column, because it takes a lot more time to answer everyone’s questions than it does to read this article. But what really matters to Steve is that a class-action lawsuit about the very issue addressed was recently upheld in federal court while we waited to publish his question.
It’s also nice when an automaker’s marketing tagline (i.e. GMC’s Professional Grade advertising schtick) comes in direct conflict with their level of customer support after the sale. Delicious irony aside, we still don’t have an answer for you, Steve. These legal movements take time, unless GM wants to squash the bad press and settle out of court. Also, that particular lawsuit pertains to vehicles made for the 2019 through ’22 model years. What can you and your 2018 GMC Canyon do in the meantime?
There’s actually another GM eight-speed transmission lawsuit, and it does include your Colorado. I’d reach out to that particular law firm and see if you can be added to the class action. But don’t blindly jump in; ask what you’d get out of your participation. I assume the biggest thing you need is a new transmission that doesn’t annoy the heck out of you, but time is money, and maybe you’ve lost a lot of time dealing with this?
There’s one other place to look for advice, and it’s something I’ve mentioned in the past. But since I wasn’t clear last time, let me do it right this time: Find the local GM dealership with the best reviews online, go to their website, find their staff page, look for a Service Director or Fixed Ops Director, and make a plan to visit the dealership when that person is in the office. Ask them candidly for their advice, and don’t be a Karen (for lack of a better phrase) about it. Honey gets the flies in this case, I assure you.
Dealerships are motivated to help customers in these cases, if they can. Darn near every dealership loves to get money from the faceless manufacturer to make a customer in their building happy. So if GM is putting a plan in place that can help you, this is absolutely in the dealer’s favor, too!
A third option is more personal: If you have a lawyer friend that you trust, ask them for professional advice. I am not a lawyer, but it looks like restitution and resolution could be a light at the end of this particular tunnel. GM could open the floodgates for dealerships to repair/replace gearboxes in the near future, and it’s always good to be on a waiting list for that resolution.
Have a question you’d like answered on Piston Slap? Send your queries to pistonslap@hagerty.com—give us as much detail as possible so we can help! Keep in mind this is a weekly column, so if you need an expedited answer, please tell me in your email.
Opt out of the class action and sue on your own. Class actions only give you token amounts. You might be able to get your transmission replaced by suing them in small claims court.
I wonder if someone like Gearstar makes something that could swap in? I get a bit lost after turbo 400, 700R4 but they seem to be up to the modern 6-speeds at least?
If factory is lame and money isn’t a barrier… go hot rod?
Here is the real deal. I own a 2017 Denali myself so I have skin in the game.
I had the hard 1-2 shift.
Note the lawsuit is for the shudder going up hill around 40 mpg. Not the hesitation.
Ok what is the problem. The trouble was the Mobil One tranny fluid in the 2017~2019 models. The fluid would absorb moisture and this would create issues with the lock up clutch and it would create a shudder. This leads to a glazed clutch on the converter.
GM has had a fix for this since 2019. They have had Mobil create a new fluid that resist the moisture. They got a long period of time would flush for free these transmissions when presented at the dealer. This has taken a major topic in the Colorado/Canyon forum to making it a rare topic.
I presented mine and the dealer with no question flushed it.
The new fluid not only resist moisture but helps recover the glazing of the converter. It works mine is still just fine.
I had a hard 1-2 shift too. Now after the first shift in the morning cold the transmission is smoother in all gears.
My transmission is much better than it was. I really have no issue with it. Are there smoother transmissions out there yes but this is no longer a problem tranny.
If the converter was too far gone glazed because it was not brought in the dealers are changing the converter.
This was all done under drivetrain warranty. If out many dealers will cut you a good deal. Some won’t. They also were given a flush machine to properly wash the tranny clean of the other fluid.
GM has tried to find the issue as for a long time it was not known as the cause then the solution. Mobil tried several fluids till they got it right. This issue is not just a GM deal. Many Tranny fluids are absorbing oil and have created some issues.
The class action is just a bunch of lawyers acting in your behave on their own. They make a settlement with GM that to you amounts to nothing. Yet they will claim much of the settlement for their dork representing you.
So this will not fix the issue.
On the other hand getting a lawyer for yourself will not fix the truck and just cost you a lot of money.
Best to go to the dealer get the blush and press to get it for free. Stand your ground and keep on the dealer and GMC customer service. They are yo say no but if you keep on them they will give. This is common for most mfgs.
The fluid is key and not cheap. The machine is important too to clean out the bad fluid. But this solves the issues.
Note too not all transmission have had the issues and past March of 2019 the new truck all got the new fluid that is still used in the next Gen models.
My truck is good and runs great I plan on hanging onto it now since they no longer sell a V6.
Today’s transmissions are very complicated and complex trying to do so much to save fuel.
The other issue is trannies today are not as good as past from anyone. The new CV trannies are a real mess all due to the need of more mpg.
We are also seeing more engine issues with all brands.
Fantastic insight, I am updating the article to reflect this.
(As someone who has needed to add Lubeguard Red to Ford gearboxes for a similar shudder, I should have looked into this!)
Experience is a hell of a way to learn.
This is all in a TSB from GM in 2019. It should still be out there.
The greatest issue was the few dealers refusing to do the work. Problem dealers are even a torn in GM side too.
Most were like mine just present the vehicle and it was done.
The real issue today is if the vehicle is out of warranty what will dealers do.
Mine was done in 2019 and still sailing smooth.
I hope this helps.
If anyone has an issue with a car. Ignore the class action deal. Go for lemon laws if needed. They are the most effective.
With the many failing engines of late from many brands that may be something to remember.
Sajeev, hyperv6 is exactly right about the torque converter “shudder” issue, which I experienced this year in my 2016 Corvette Stingray at 27000 miles. The water which accumulates in the transmission fluid causes the converter to slip and results in a feeling correctly described as running over speed bumps. My Chevy dealer said a single fluid drain and fill “might” fix it, but after a bit of research, I found 2015-2017 Corvette Service Bulletin #16-NA-175 which is very detailed. It calls for a fluid drain; evacuating all cooling lines and 3 complete fill and drain procedures. Each is followed by running the car on a lift for 10 minutes and cycling through the gears. The final fluid fill finishes the job and in the case of my Vette completely corrected the shuddering. From what I’ve read, the problem has occurred in as few as 4000 miles and as many as 56000. Interestingly, the same bulletin refers to Chevy/GMC trucks, Camaros and many Cadillac models.
Thank you for sharing the details of this process, as I assumed it would be more involved than a conventional flush and fill. Turns out it is quite involved!
The fluid flush/change worked on my ’17 Colorado. The dealer was not in a generous mood, charged me north of $300, but I figured it would be unwise to trust an independent to have the correct new fluid.
I have found that the magic number for automatics is 6. You try to cram too many gears in them and you start having problems
The real trouble is not the number of gears. It is the lock up converters, the way the computers kill the torque during the shifts to smooth them out and to try to make smaller lighter transmissions live.
Many engines today tune down at shit points as the grand missing would implode otherwise.
I’ve missed a gear and had one of those points…
LOL!
So what you’re saying here is, and I’m reading between the lines a little… “Never buy another GM product again, moron”.
Got it!
You can Google every brand and each will show shudder issues. .
So GM has a known issue and is changing transmission fluid for free to those who complain – depending on the dealer of course and their willingness to admit the problem and be helpful. I would imagine other less helpful dealers will just say it’s normal or want to charge for all manner of services without disclosing that this is a known issue. About what I’d expect from GM.
John welcome to the reality of the real world legally.
The Dealer’s are protected agents from the MFG’s. They cannot tell them what to sell cars for and often even when dealer agreements are broken the punishments are limited.
The mfgs are between a rock and a hard place. They cannot buy out the franchise’s but they are stuck with dud dealers.
This is an industry wide issue, they do is often limit fall back money and they restrict allocations etc. But pulling the franchise is seldom permitted by government regulation.
I have seen several local dealer get punished from several mfgs in Icluding GM but they are generally stuck with them
You may be butt hurt over GM but they all face similar issues. GM’s greatest issue is too many legacy dealers they can’t kill.
Can confirm, Chevy of Troy Ohio openly admitted it to me. I am a diesel mechanic by trade. At 400 miles on the odo, I felt a bad shudder, and they KNEW, that these transmissions were filled at the factory with the incorrect fluid. 2019 Colorado, 4 door, 4wd, auto Trans, LT model. They took the truck in for a fluid swap, was actually surprised that I noticed it at 400 miles, and said most sent recognize it till 3-4 thousand.
I have a 2016 Stingray with automatic eight speed. After hard acceleration and trying to stop, it shook violently and liked to refuse to down shift. This symptom developed 2-3 after I had purchased car new. I went to my local friendly and good Chevy dealer. I talked to mu regular Vette advisor, who suggested I let them keep the car over night and replace trans fluid with new formulated synthetic Mobil 1 trans fluid. She told me the old had to be drained(it has tendency to retain humidity/water droplets over time), and every droplet of old had to be drained and dried (hence why they needed to keep it over night). They did not charge me a penny. Seven years later, the Stingray shifts beautifully and keeps its side of garage glowing in that gorgeous Admiral blue color.
Additional info. If the shudder is there it may take some miles to recover with the new fluid. In my case it was not pronounced so it was better the first drive.
The key is the flush machine it will change the oil at temperature.
It used to be we generally had 2 fluids for nearly all cars. Today we have a great number of fluids over a wide range of transmissions. Even more manual trannies use Auto fluids.
These issues are getting more common by all mfgs. The best way to describe this is it is Simply Complicated.
One last thing avoid the quick shudder fix things on the market. The fix for the GM transmission is the Mobil Blue fluid.
Great article and great comments! First time on this site. I’ve been a tech all my life but not by choice. That is a different story. The problem with GM transmissions have been going since I started fixing the POS Hydrormatiic transmissions! Which I didn’t want to do in the first place.
Thanks UAW for forcing our jobs overseas. Now most part failures are because of cheap materials from overseas.
Thanks manufacturers for taking the cheapest way out.
Shutter on 8 speeds should be revised to include weather you use as a work truck or grocery getter. Either way it should be changed to the Mobile 1 fluid but if you don’t drive it often it will take 1 to 2 thousand miles to start to feel the improvement
Yes I stated it can take time to recover a glazed converter clutch.
And yes this applies to all 8 Speeds. Corvettes to Trucks.
Sounds like a load of crap to me. If a harsh 1-2 shift upsets, then what would people act like if their engine grenaded? We used to put shift kits in our muscle car automatics that would snap your neck and everybody loved it, because there was no doubt the shift was positive and full fluid pressure was applying the clutch pack or band that lead to no slipping. Fast forward to today, and a firm shift is a crime against humanity.
I had a 2022 Canyon. It wasn’t a firm upshift or delay, sometimes it felt as if you were hit from behind. Other times, smooth as silk. No pattern or correlation with anything that I could observe. It was like the transmission would flare in the 1-2 shift, pausing for a second in neutral and slamming into 2nd gear.
Mine would also do this on the first start of the morning when putting it into gear. Some days it would chirp the tires (with the foot brake on), others were more calm. This was a little more consistent with the weather. Warm summer days were better than cold winter days.
I brought the truck in to the dealer because it was brand new. They said I was putting it into gear too soon after starting the engine. The rpms would rev up at start, then drop to normal idle. I always wait until the idle stabilizes, so that’s bogus. Not only that, GM has that dumb gauge cluster that maxes out then drops to normal at start-up. They said all of the conditions I witnessed were normal and the truck had the latest oil upgrade.
I didn’t really mind the quirks, but was unsure how this was going to affect the life of the transmission. I checked the fluid and at 30k it looked perfectly clean and red, so maybe it was just fine.
I traded the truck because of my job change. I liked it but my needs changed.
Harsh, not firm, and not the shock any of the drivetrain pieces were designed to withstand.
My son has a 2018 Suburban with an AT and he had to pay the Chevy dealer $5k for a new tranny as his suposedly couldn’t be rebuilt because of computerized this and that. Sounds like Chevy should have never scrapped the Powerglide. Every TH350 that I ever had, leaked like a seive, after sitting idle for any amount of time. We need to go back to manual transmissions that don’t leak.
At least there is a fluid fix for this. I feel for those who didn’t get the fluid in time. So what about the new 10-speed transmissions? I’m hearing a bunch of issues with them also.