# Does your AUTOMATIC transmission shift jerky/erratically?



## spacedout (Dec 7, 2010)

Wish I could have a chance with a 2011 car to see how much difference there is, my 2012 automatic shifts very predictably with a nice level of firmness. In manual mode however sometimes it seems to grab a bit hard & not in a nice way.


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## jdubb11 (Mar 14, 2012)

jerky, mainly on downshifting.


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## cruzers (Dec 13, 2010)

I'm going to have to say no. It is a small motor with a busy six speed transmission. It's not your normal older type GM transmission where they would free wheel when cruising, these automatics drive more like dual clutch transmission. Best way I can describe it, is like driving a manual, but the transmission is shifting for you. I like the fact when going downhill or even straight you can slow down without applying the brakes as frequently, unlike free wheeling transmission. This is definitely a love or hate transmission.


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## Djc83 (Mar 25, 2012)

I will have to say yes, my 2011 LT1 AT6 does shift erratically or jerk but not all the time. It does jerk really bad when downshifting in M6 mode. I would love to see an improvement come from GM on the shift points and duration of the shift. I have had the car act like it was going to stall three times; once backing up and the others in drive from a stop light. But overall I still love my Cruze!


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## David1 (Sep 16, 2011)

The more miles it gets, the worse it is getting.


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## sedanman (Dec 10, 2010)

My 2011 2LT automatic trans. shifts fine for me. No problems.


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## obermd (Mar 3, 2012)

For those with 2012s and jerky shifts, what are the manufacturing dates on your car?


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## GoldenCruze (Dec 18, 2011)

I have to say no because I believe it is behaving normally. Shifting is more noticeable with this transmission than on others I've had. Some downshifts do result in a bit of a jerk when they engage, which I attribute to a combination of gear ratios and programmed shift points. But I don't think there is anything wrong going on.


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## 70AARCUDA (Nov 14, 2010)

GoldenCruze said:


> I have to say no because I believe it is behaving normally. Shifting is more noticeable with this transmission than on others I've had. Some downshifts do result in a bit of a jerk when they engage, which I attribute to a combination of gear ratios and programmed shift points. But I don't think there is anything wrong going on.


*CAUTION--HUMOR embedded here!

*Which is ocurring: (a) *YOU* are _adapting_ to how the transmission works or (b) the *TRANSMISSION* is _adapting_ to how you drive?


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## ErikBEggs (Aug 20, 2011)

2011. YES, it WAS a problem when I first bought the vehicle. Shifting problems were 100% resolved by Trifecta reprogramming the ECU and TCU.


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## Sunline Fan (Jul 29, 2012)

I'm inclined to say no. It jerks quite noticeably in manual mode only when going between second and third. I've seen on quite a few occasions where the DIC will suddenly flash M3 when I tap it, but then go back down to M2 and it won't shift. Then I try again and it'll go, perhaps because I have more speed.

It doesn't seem to be a problem when in full automatic.

BD 2/23/12.


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## jdubb11 (Mar 14, 2012)

obermd said:


> For those with 2012s and jerky shifts, what are the manufacturing dates on your car?


4/12


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## 2013Cruze (Aug 4, 2012)

No not at all


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## JoshCruzeRs (Jul 31, 2012)

I have a 2012 automatic with 8000 miles on it and yes it does shift hard during acceleration sometimes


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## GoldenCruze (Dec 18, 2011)

> CAUTION--HUMOR embedded here! Which is ocurring: (a) YOU are adapting to how the transmission works or (b) the TRANSMISSION is adapting to how you drive?


 A bit of both. I think that it smoothed out in the first few thousand miles. But one thing to get used to was shifting during turns in an intersection. There tended to be an abrupt upshift happening often there. I know that I have somehow changed my throttle habits to compensate for that. It'll be interesting to see how those 9 and 10 gear transmissions that Ford and GM are working on together perform when they finally hit the road. They could shift worse, or not.


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## cruze2011white (Feb 2, 2011)

I had a 2012 when mine was getting repaired for a transmission leak and it shifted much better than my 2011. It also shifted much quicker in manual mode than mine did. I also noticed it seems to shift better if the air conditioning is on or when i'm towing my seadoo. It seems that if the transmission has some stress on it such as going up a long hill also it shifts better. I just live with mine because most of my driving is on the highway but i agree they need a software update for the 2011's.


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## djhamp (Jun 29, 2012)

2012 LS: it shifts harder (firmer?) than any car I have ever owned. Up and down, most of time it seems to be working OK, just firm. Sometimes slowing down it will jerk pretty good going into a lower gear. I find myself letting off the gas a little when accelerating to let it up shift more smoothly


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## Bohdan (Apr 28, 2012)

Mine is shifting great no problems at all. Build date 5/2012.


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## rustinn (Jun 7, 2012)

I've pinpointed when the jerking occurs... Every time I let off the brakes and cruise at lower speeds (under 30 mph), the car pops in and out of gear real harshly. It's pretty bad driving this thing in stop-and-go traffic.


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## Chevy Customer Care (Oct 29, 2011)

I'm sorry to hear about these concerns. If any of you would like me to investigate further, please send a DM! Thank you.

Katie (Assisting Stacy), Chevrolet Customer Service


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## ErikBEggs (Aug 20, 2011)

rustinn said:


> I've pinpointed when the jerking occurs... Every time I let off the brakes and cruise at lower speeds (under 30 mph), the car pops in and out of gear real harshly. It's pretty bad driving this thing in stop-and-go traffic.


That is DCFO, not shifting out of gear. It is a pain in the ass, but at least it is saving you fuel economy. The jerk are the injectors cutting off and firing again when you press on and off the gas respectively. There is roughly a ~1 second delay between getting on / off the throttle and that slight jerk. It is a subtle thing I've noticed over the 30,000 miles


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## Jaycruze (Jul 11, 2011)

I see you have the tune, so you're saying the tune has no effect on the delay? I was hoping the tune would fix this, i might not get it if it doesn't.

the delay I'm referring to is the (rolling stop delay) you dont fully stop and get back on the gas.... its really annoying because you put your foot down and nothing happens, then it jumps into gear and flings forward.





ErikBEggs said:


> That is DCFO, not shifting out of gear. It is a pain in the ass, but at least it is saving you fuel economy. The jerk are the injectors cutting off and firing again when you press on and off the gas respectively. There is roughly a ~1 second delay between getting on / off the throttle and that slight jerk. It is a subtle thing I've noticed over the 30,000 miles


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## Tea (Nov 20, 2012)

*Transmission Jerk*

Hi, some sharing to everyone who drives Cruze, here are some ways you may try to rectify your own;

1. Change ATF (Auto Transmission Fluid - 5 litre) as regular as you can. If you drive more frequent in city with heavy traffic (change at 10k to 15k km), if you drive more frequent on freeway which encounters lesser gear shift ( change at 20k). One issue which we can think of is that the ATF loses its lubricant function or cooling function for a period of time in the gearbox. More gearshifts mean more friction and heat, which tends to break down the function of ATF and oxidize. If you change the ATF, look at the colour, it is brown almost black and burnt smell. (new ATF is red in colour) Try to maintain ATF as fresh as possible to enjoy your ride.

2. If you are not satisfied with the lag of gear shift, there is a "plug and play product - booster" which you may be interested in, it helps to quicken the respond of gear shift.

We are a team of cruzers who try to troubleshoot this gear issues, so far there is no problem and everyone is enjoying the ride. We change ATF frequently between 10k and 20k km or once in six months. When you drain out the old ATF, you need to fill in 5 litres. (4 litres isn't enough and gear will jerk at shift 1,2 and 3)

Hope this sharing will help Cruzers out there, cheers.


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## zbhover (Jun 19, 2011)

I just thought I'd pass this on to all you guys. I'd say I'm 95% happy with how my 2011 auto LS shifts now.

Since I got the car new I've had the issues with it lagging when taking off from a stop, or jerking, etc, not wanting to down shift when you try to pass, all the stuff everyone is always complaining about. I got in the habbit of driving mostly in manual mode, of course then you can't use 1st.......

My dealer had to replace my body control module because it crapped out and I'm guessing it reset the learned programming for the trans because it SUCKED more than ever right after they did it, It was like when I first got the car and I looked like an idiot who couldn't drive a stick.... LOL So in the 4,000 miles or so after the new BCM I drove ONLY in manual mode, maybe only 10-20 miles of auto mode driving. So I figured that a couple days before I took the car to the dealer for a bad TPMS I'd drive in auto mode and make a list of all the stupid things this "smart" transmission did and see if they could do anything.................. Well it doesn't do any of those stupid things anymore. When I take off from a stop it reliably and predictably shifts and accelerates, no more delays in shifting like its thinking real hard about what to do, if I step on the gas to pass someone it instantly down shifts and I'm off. I've probably drove about 100-150 miles in auto mode before going to the dealer and I no longer had any complaints about the transmission!!! Since that visit I've probably drove 800+ miles and would say I'm about 95% happy with the way it shifts. Every now and then if I'm coming to a stop and the light changes just before I come to a stop and I give it a little gas just as its shifting to 1st the trans will get a little confused, but nothing major. Also if I'm real light on the gas trying to get better gas mileage 1-2 and 2-3 shifts can be a little sluggish, but nothing major. I'm just happy now that if I step on the gas to get out in traffic there is no hesitation.

I don't know if the trans "learned" how it should be shifting from me driving only in manual mode where I shifted like it should??? Or if the faulty bcm was messing the the trans, or if it got new programming or what??? In the past they said there was no new programing for the trans??? 


It might be worth someones trouble to reset their trans and drive in manual mode for a while and see if that changes anything?


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## obermd (Mar 3, 2012)

Tea said:


> We are a team of cruzers who try to troubleshoot this gear issues, so far there is no problem and everyone is enjoying the ride. We change ATF frequently between 10k and 20k km or once in six months. When you drain out the old ATF, you need to fill in 5 litres. (4 litres isn't enough and gear will jerk at shift 1,2 and 3)
> 
> Hope this sharing will help Cruzers out there, cheers.


Interesting observation. I wonder how many automatics don't have enough transmission fluid causing low speed shifting problems.


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## jadedgamerx (Nov 12, 2012)

I have a 2012 Cruze 1FL (fleet vin), forgot to check the manufactured date on the door this morning and don't want to walk all the way back to the parking ramp on lunch just to figure it out right now. I've owned the vehicle since mid-September and bought it with 22K on the clock already so I have no idea if it has gotten worse since new or not.



jdubb11 said:


> jerky, mainly on downshifting.


To elaborate on this: for an automatic transmission, IMO this car has an overly large amount of line pressure during downshifting compared to other automatic cars I have owned (especially during controlled braking and coasting scenarios). It would be welcome during a negative grade/downhill situation off-throttle, but is too strong elsewhere.  Non-scientific seat of the pants comparison to manual cars I have owned of similar displacement?: It feels like about 80-90% of available engine braking forces are being applied during the downshift into 3rd, 2nd, and 1st (almost full clutch lockup) and the transmission continues to hold this pressure while slowing down. It's not a very gradual release and a bit too much for the weight of the car, I could see this causing traction loss in icey conditions.



rustinn said:


> I've pinpointed when the jerking occurs... Every time I let off the brakes and cruise at lower speeds (under 30 mph), the car pops in and out of gear real harshly. It's pretty bad driving this thing in stop-and-go traffic.


Elaborating on this experience more, it seems like the following:
Lag from a roll (off throttle to on throttle) in stop and go:
1) Injector cut for fuel economy turns into lag when the light turns green and you re-apply the gas.
2) During stop and go conditions, it seems to like to shift between M1 and M3 depending on speed and provide engine braking to reduce wear on the brakes (this seems intentionally engineered to me considering it's prominence).

My motorcycle does this because of fuel cut under closed throttle, it's annoying on that too and makes for jerky throttle response when attacking corners and re-applying throttle mid-corner after apex. Luckily they make things like fuel cut eliminators for bikes.

Lag from a stop, seems to be a combination of:
1) Turbo ramp-up rate, seems to depend on octane a bit (91 has less KR at initial spool up from what I can tell).
2) IC heat-soak from a stop
3) Electric throttle response time
4) Transmission line pressure off the line, could use a bit more RPMs before it starts to disengage the clutching mechanism to avoid turbo-lag, low torque area of the powerband. Not asking for drag-racing power off the line, bit it seems a bit conservative to me given displacement and weight of the car. 1800-2K RPM and a gradual slip off the line would be perfect under partial throttle/boost.

IMO, this item is a major wear concern: Free-wheeling between shifts: car feels like when it is up-shifting from 1st into 2nd, 2nd into 3rd and 3rd into 4th, etc - that it has some "float" time where there is a mild RPM increase between the gears. Like the ECU is giving it a mild amount of throttle and the TCU is completely engaging the clutching mechanism to complete the shift momentarily. Wasted fuel IMO and annoying as the acceleration force is a bit unpredictable.

I come from a lot of high performance cars and I may be a little picky, but even my $250 Buick Century "winter beater" shifted more predictably than this thing.

I'm planning on having the transmission behavior above and my brakes checked out when I bring the car in for service, I'll open a ticket with customer service at that time if I don't find resolution with the dealer. /offtopicabit/ My car is a Lordstown, Ohio built model and it appears that the rear brakes are in pretty rough shape (making grinding noises) and the front rotors are definitely warped. There is major pad stiction when releasing the pedal and the car kind of lurches forward once the brakes finally let go as the transmission is already attempting to move the car. My fear is that a combination of a not adequately tuned braking system from the assembly line combined with 20k miles of rental duty have brought me to the point of needing major brake work already. /offtopicabit/


I truly DO NOT want this post to seem overly negative, I actually think GM for the most part built a really nice car overall. It just seems like the transmission could have used A LOT more real world testing and tuning prior to final release. The problems I'm having with my 2012 model appear to be the same as the 2011, which leads me to wonder if there is some overlap. I'll get that production date tonight and edit this post for further clarify.


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## Sunline Fan (Jul 29, 2012)

I drove mine in automatic mode today for the first time in a while. lol, hated every minute of it. It revved up quite high before it shifted, compared to what I'm used to. Not to mention, getting on the highway, I'm used to merging on in 5th gear with decent acceleration, and here it dropped down to 2nd or 3rd and basically redlined to get similar acceleration to what I'm used to.

It shifted VERY smooth though, I'll give it that. Much smoother than manumatic mode.


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## DuluthCruze (Aug 14, 2012)

For me it seems to depend on how I drive it. It's a small engine and the trans is busier than a 4 speed in trying to anticipate the gear you need, especially when braking then accelerating again. If I give it throttle input that is steady and not quickly varying, I find the trans does well. If I get on it, let off, then get on it quickly, I can confuse the trans since it is reacting to my input. I'm glad the auto has a manual mode, but I drive in normal auto most of the time.


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## DuluthCruze (Aug 14, 2012)

Sunline Fan said:


> I drove mine in automatic mode today for the first time in a while. lol, hated every minute of it. It revved up quite high before it shifted, compared to what I'm used to. Not to mention, getting on the highway, I'm used to merging on in 5th gear with decent acceleration, and here it dropped down to 2nd or 3rd and basically redlined to get similar acceleration to what I'm used to.
> 
> It shifted VERY smooth though, I'll give it that. Much smoother than manumatic mode.


Good point. I agree with you about it revving too high. I understand high revs at WOT, but even at 1/2 throttle it hangs unnecessarily on a gear before up shifting. Drives me nuts. This is where I'll often slap it over to M mode and help it's little brain.


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## wallbngr (Feb 2, 2012)

My Cruze is a 2011 RS ,and when it shifts down from 5 to 4 it "bangs" into gear ..
It has done that since It was new.. 
Gil Younger makes Shift kits ,I don't know if there is one available for this tranny yet ,
I would imagine they are too new to be in the rebuild cycle yet..


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## TBN27 (Oct 1, 2012)

Mine would shift hard at time when going into reverse. When i sent it in for a faulty sensor which was reading falsly that the transmission was not cause correct idle, they installed a software update. Since then, the transmission has been smooth as butter.


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## smoldy (Nov 23, 2012)

I have had many problems with my transmission on my 2012 Cruze. It jerks badly when shifting, have have had problems with trans slipping, also, it "slams" or "knocks" when going from reverse to drive. I have taken it to my dealer a few times now, and they have turned me away each time without finding a problem. I'm beginning to wonder if the problem is that hard to find, or if I just need to find a new dealer.


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## simplmn72 (Aug 18, 2012)

My answer is yes. I have 2012 Cruze RS. It jumps back and forth thru the gears like it is lost and doesn't know which way to go. I bought it in Missouri and after many trips to the dealership a problem was found and fixed and it did seem to remedy the shifting problem a little but it is still there. My U.S. 2012 Cruze had an European gauge cluster and everything was programed for the European models. After they changed the gauge cluster which G.M. wanted back asap and reprogrammed everything then a lot of problems went away.


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## TawnieT (Sep 12, 2012)

Yes my 2012 shifts really hard. I bought it new from the dealership three months ago and its spent the last two weeks in the service department having the transmission fixed. They can't tell me how long it will take only that it is definately the transmission and the further they get into it the worse it is.


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## Yates (Aug 24, 2012)

No but I only have 2000mi so far.


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## eriecruizer (Mar 6, 2011)

Our 2011 LT 6 speed auto has over 20,000 miles and is now resting for the winter. We have had no noticable issues with it, including no transmission concerns, since purchased in December 2010. There is a learning curve both for the driver and for the car. We drive to max mileage and last achieved over 45 mpg on a 250 mile trip in late October just before heading into storage. This is not your grandfather's Chevy; treat it like a fine woman and it will take good care of you.  . Ease the tranny thru the gears. No pedal to the metal for this Cruze.


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## stevesjh (Aug 29, 2011)

Definitly yes on my 2012!


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## Erastimus (Feb 9, 2012)

The Cruze automatic transmission is a piece of crap. I had it back after one week and they replaced the valve body (or so they say). It's no better. I complained again at first oil change at 6500 miles and they've told me basically to buzz off. On a cold morning, the darn thing doesn't want to shift from 2nd to 3rd until it thinks about it for a few seconds. This goes on until the trans is fully warmed up.


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## athena15 (Jul 17, 2012)

*Yes*

2011 Chevy Cruze LTZ 1.4T


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## toughchic2325 (Aug 5, 2012)

i have a 2012 chevy cruze no extra letters like Lt or anything just a cruze and yes the shifting is jerky and odd.... i have addressed this at the dealership to get no results.... when a car reaches 5000+ RPMs before shifting there is a issue... my car even rolls backwards on a incline.... it is a automatic transmission.... i hope starting this poll and others saying something will have GM do something about it... and btw it was manufactured on 3/2012.... and MPG... haha thats another joke.... i get 25MPG city and 28 Hwy.... :-( not very happy with my cruze...


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## 70AARCUDA (Nov 14, 2010)

...a lot of Cruze owners have realized that all the_* sales-pitch-pablum *_and "free" _*kool-aid *_are NOT as GM promised.


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## Jim Frye (Mar 16, 2011)

I wonder when they switched over to the 2nd gen. 6T40 in the Cruze? I thought it was long before March.


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## Chevy Customer Care (Oct 29, 2011)

toughchic2325 said:


> i have a 2012 chevy cruze no extra letters like Lt or anything just a cruze and yes the shifting is jerky and odd.... i have addressed this at the dealership to get no results.... when a car reaches 5000+ RPMs before shifting there is a issue... my car even rolls backwards on a incline.... it is a automatic transmission.... i hope starting this poll and others saying something will have GM do something about it... and btw it was manufactured on 3/2012.... and MPG... haha thats another joke.... i get 25MPG city and 28 Hwy.... :-( not very happy with my cruze...




toughchic2325,
I would like to apologize for the issues that you are experiencing with your Cruze. I would like to look into this further for you. Can you please send me a PM with your name, address, phone number, VIN, current mileage and the name of your dealer? I look forward to your response as well as being able to assist you with your concerns. 
Thank you,
Stacy Chevrolet Customer Service


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## Aussie (Sep 16, 2012)

Just clocked up 4,000km on my Holden Cruze Diesel auto and find it the smoothest auto I have ever driven. You can only feel the first two changes before you can no longer tell what gear you are in. Driving at 70 kph at 1700 rpm I put the car in manual mode to see what gear the car was in and was surprised to see it was only in 4. My guess is that a diesel needs to be kept above a certain rpm as well max rpm of 4,500 and the transmission is tuned to do this. Having modified an earlier Holden I noticed that the changes worked much better with more power and torque.


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## Stewscruze (Jan 31, 2013)

*It's how it was designed*

2011 HYDRA-MATIC 6T40 (MH8) SIX-SPEED AUTOMATIC
HYDRA-MATIC 6T45 (MH7 FWD, MHC AWD) SIX-SPEED AUTOMATIC

Vehicle Applications
• Buick LaCrosse (MH7)
• Buick Regal (MH7)
• Chevrolet Cruze (MH8)
• Chevrolet Equinox (MH7, MHC)
• Chevrolet Malibu (MH8)
• GMC Terrain (MH7, MHC)

Product Highlights
• Advanced clutch-to-clutch shift operation
• Tuned for quick launch feel and fuel-efficient cruising
• Compact, one-piece case
• Adaptive shift controls
• Hyper-elliptical torque converter saves space
• Maximum engine torque rating of 177 lb.-ft. (240 Nm) – MH8
• Maximum gearbox torque rating 277 lb.-ft. (375 Nm) – MH8
• Maximum engine torque rating of 232 lb.-ft. (315 Nm) – MH7, MHC
• Maximum gearbox torque rating 315 lb.-ft. (425 Nm) – MH7, MHC

Overview
Six-speed automatic transmissions are integral in GM’s initiative to offer vehicles with excellent fuel economy, and the Hydra-Matic 6T40/6T45 transmissions are delivering on that promise. Designed for FWD and AWD applications, they are used in many of GM’s newest and most popular models, including the Chevrolet Equinox and Buick LaCrosse.

The 6T40 (MH8) and 6T45 (MH7, MHC) are essentially the same transmission, with the 6T45 rated for greater torque capacity. Each is part of GM’s family of technologically advanced, fuel-saving six-speed automatics. Shared traits between the versions – and other Hydra-Matic six-speeds – reduce complexity, size and mass, including clutch-to-clutch operation that enables the six-speed to be packaged into approximately the same space as a four-speed automatic. The transmissions also share an overall 6.11:1 gear ratio spread, which contributes to their signature balance of performance and fuel economy.

Because of the wide ratio spread, first gear is a very high ratio, which provides brisk acceleration from a stop. Sixth gear, however, is an overdrive ratio, which keeps the engine revolutions lower for highway cruising, reducing engine friction losses and optimizing fuel economy.

6T40/6T45 Differences
To support the 6T45’s greater torque capacity, it features a 1.25-inch-wide output chain, versus a 1-inch-wide chain in the 6T40; and the input gear set of the 6T45 uses five pinion gears, versus four pinions for the 6T40. The case of the 6T45 is slightly larger and includes a heavier ribbed case for additional strength.

On-Axis Design
Instead of “folding” the transmission around the end of a transversely mounted engine, which has been one of the dominant GM transaxle design conventions, the 6T40/6T45 contains all of the gearing in line with the crankshaft centerline of the engine. The advantages of this layout can translate to a shorter overall vehicle length, more interior room and lower powertrain height.

Clutch-to-Clutch Shift Operation
Three planetary gearsets are used with three stationary clutches and two rotating clutches, which save space compared to freewheeling designs. Freewheeling mechanisms allow perfect timing between shifts, but also take up more space and add more components to the transmission. However, due to the electronic controls, the clutch-to-clutch concept of the 6T40/6T45 delivers the same accurate shift timing.

Gear changes from second to sixth gear ratios are accomplished with a precise clutch-to-clutch action, where the clutch is engaged in one gear at exactly the same time it is released in another. The first-to-second upshift, however, is a freewheeling action, where the second gear clutch engages while the first gear one-way clutch spins freely. This allows a greater degree of smoothness at lower vehicle speeds.

Adaptive Shift Controls
Adaptive shift controls include automatic grade braking, which commands the transmission to remain in a lower gear if the vehicle is decelerating or coasting on a downgrade. This takes advantage of engine braking to prevent unwanted acceleration. This reduces the need for the driver to brake during a hill descent. The control module receives input that monitors brake pedal usage, vehicle acceleration rate, throttle position, and even whether a trailer is connected to the vehicle.

Space-Saving Hyper-Elliptical Torque Converter
The torque converters in the 6T40 (205 mm) and 6T45 (236 mm) use a single-plate lock-up clutch and feature a “hyper-elliptical” oval cross-section shape. This design reduces the thickness of the torque converter, reducing the space it needs and keeping the overall width of the engine and transmission as narrow as possible, for packaging advantages. The single-plate lock-up clutch uses GM’s electronically controlled capacity clutch (ECCC) technology to help dampen engine vibrations and ensure smooth operation.

IX Gear Pump
A compact on-axis, fixed-displacement IX gear-type fluid pump provides hydraulic pressure for shifting and lubrication. The pump features an IX gear (Drive/Driven) with a machined crescent in the pocket, which reduces internal leakage and optimizes hydraulic efficiency. The inlet jet nozzle feature in the IX gear-type pump provides for increased pump suction pressure, which helps optimize noise and vibration characteristics.

Ground and Honed Gears
To minimize gear noise, as well as vibration, the transmissions’ helical gears are ground and honed to ensure exact dimensions and tolerances. With closer tolerances, the gears are less prone to characteristic whining or humming, and the transmissions operate with exceptional quietness.

Unique Input Shaft Bushings
The input shaft requires no machining for grooves to contain fluid seals, which allows the shaft to retain maximum strength for its size and minimize cost.

Maintenance
The 6T40/6T45 is filled for life with DEXRON®-VI premium fluid, which does not require changing under normal use. It was developed to have a more consistent viscosity profile; a more consistent shift performance in extreme conditions; and less degradation over time. The fluid was validated to improve durability and shift stability over the life of the transmission.

Transmission Control Module
A 32-bit transmission control module (TCM) monitors transmission performance and compensates for normal wear in components such as clutch plates, so transmission performance remains consistent for the life of the transmission. The control module also “tests” the components of the transmission following assembly to optimize the interaction of the components.

The TCM is mounted inside the transmission, where temperatures remain mostly constant compared to an external-mounted module. It is small in size, which helps minimize the overall size of the transmission. The transmission and module are assembled together, so no additional connections are necessary during vehicle assembly.

TECHM
The 6T40/6T45’s transmission electronic hydraulic control module (TEHCM – pronounced “TECH-im” by engineers) contains basic software and algorithms shared among all Hydra-Matic six-speed variants, including RWD, FWD and AWD. The module is located inside the transmission, which reduces manufacturing complexity, and requires only vehicle-specification calibration to the core program. The TECHM also enables features such manual shift control and grade logic.

# # #


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## Stewscruze (Jan 31, 2013)

2011 HYDRA-MATIC 6T40 (MH8) SIX-SPEED AUTOMATIC
HYDRA-MATIC 6T45 (MH7 FWD, MHC AWD) SIX-SPEED AUTOMATIC

Vehicle Applications
• Buick LaCrosse (MH7)
• Buick Regal (MH7)
• Chevrolet Cruze (MH8)
• Chevrolet Equinox (MH7, MHC)
• Chevrolet Malibu (MH8)
• GMC Terrain (MH7, MHC)

Product Highlights
• Advanced clutch-to-clutch shift operation
• Tuned for quick launch feel and fuel-efficient cruising
• Compact, one-piece case
• Adaptive shift controls
• Hyper-elliptical torque converter saves space
• Maximum engine torque rating of 177 lb.-ft. (240 Nm) – MH8
• Maximum gearbox torque rating 277 lb.-ft. (375 Nm) – MH8
• Maximum engine torque rating of 232 lb.-ft. (315 Nm) – MH7, MHC
• Maximum gearbox torque rating 315 lb.-ft. (425 Nm) – MH7, MHC

Overview
Six-speed automatic transmissions are integral in GM’s initiative to offer vehicles with excellent fuel economy, and the Hydra-Matic 6T40/6T45 transmissions are delivering on that promise. Designed for FWD and AWD applications, they are used in many of GM’s newest and most popular models, including the Chevrolet Equinox and Buick LaCrosse.

The 6T40 (MH8) and 6T45 (MH7, MHC) are essentially the same transmission, with the 6T45 rated for greater torque capacity. Each is part of GM’s family of technologically advanced, fuel-saving six-speed automatics. Shared traits between the versions – and other Hydra-Matic six-speeds – reduce complexity, size and mass, including clutch-to-clutch operation that enables the six-speed to be packaged into approximately the same space as a four-speed automatic. The transmissions also share an overall 6.11:1 gear ratio spread, which contributes to their signature balance of performance and fuel economy.

Because of the wide ratio spread, first gear is a very high ratio, which provides brisk acceleration from a stop. Sixth gear, however, is an overdrive ratio, which keeps the engine revolutions lower for highway cruising, reducing engine friction losses and optimizing fuel economy.

6T40/6T45 Differences
To support the 6T45’s greater torque capacity, it features a 1.25-inch-wide output chain, versus a 1-inch-wide chain in the 6T40; and the input gear set of the 6T45 uses five pinion gears, versus four pinions for the 6T40. The case of the 6T45 is slightly larger and includes a heavier ribbed case for additional strength.

On-Axis Design
Instead of “folding” the transmission around the end of a transversely mounted engine, which has been one of the dominant GM transaxle design conventions, the 6T40/6T45 contains all of the gearing in line with the crankshaft centerline of the engine. The advantages of this layout can translate to a shorter overall vehicle length, more interior room and lower powertrain height.

Clutch-to-Clutch Shift Operation
Three planetary gearsets are used with three stationary clutches and two rotating clutches, which save space compared to freewheeling designs. Freewheeling mechanisms allow perfect timing between shifts, but also take up more space and add more components to the transmission. However, due to the electronic controls, the clutch-to-clutch concept of the 6T40/6T45 delivers the same accurate shift timing.

Gear changes from second to sixth gear ratios are accomplished with a precise clutch-to-clutch action, where the clutch is engaged in one gear at exactly the same time it is released in another. The first-to-second upshift, however, is a freewheeling action, where the second gear clutch engages while the first gear one-way clutch spins freely. This allows a greater degree of smoothness at lower vehicle speeds.

Adaptive Shift Controls
Adaptive shift controls include automatic grade braking, which commands the transmission to remain in a lower gear if the vehicle is decelerating or coasting on a downgrade. This takes advantage of engine braking to prevent unwanted acceleration. This reduces the need for the driver to brake during a hill descent. The control module receives input that monitors brake pedal usage, vehicle acceleration rate, throttle position, and even whether a trailer is connected to the vehicle.

Space-Saving Hyper-Elliptical Torque Converter
The torque converters in the 6T40 (205 mm) and 6T45 (236 mm) use a single-plate lock-up clutch and feature a “hyper-elliptical” oval cross-section shape. This design reduces the thickness of the torque converter, reducing the space it needs and keeping the overall width of the engine and transmission as narrow as possible, for packaging advantages. The single-plate lock-up clutch uses GM’s electronically controlled capacity clutch (ECCC) technology to help dampen engine vibrations and ensure smooth operation.

IX Gear Pump
A compact on-axis, fixed-displacement IX gear-type fluid pump provides hydraulic pressure for shifting and lubrication. The pump features an IX gear (Drive/Driven) with a machined crescent in the pocket, which reduces internal leakage and optimizes hydraulic efficiency. The inlet jet nozzle feature in the IX gear-type pump provides for increased pump suction pressure, which helps optimize noise and vibration characteristics.

Ground and Honed Gears
To minimize gear noise, as well as vibration, the transmissions’ helical gears are ground and honed to ensure exact dimensions and tolerances. With closer tolerances, the gears are less prone to characteristic whining or humming, and the transmissions operate with exceptional quietness.

Unique Input Shaft Bushings
The input shaft requires no machining for grooves to contain fluid seals, which allows the shaft to retain maximum strength for its size and minimize cost.

Maintenance
The 6T40/6T45 is filled for life with DEXRON®-VI premium fluid, which does not require changing under normal use. It was developed to have a more consistent viscosity profile; a more consistent shift performance in extreme conditions; and less degradation over time. The fluid was validated to improve durability and shift stability over the life of the transmission.

Transmission Control Module
A 32-bit transmission control module (TCM) monitors transmission performance and compensates for normal wear in components such as clutch plates, so transmission performance remains consistent for the life of the transmission. The control module also “tests” the components of the transmission following assembly to optimize the interaction of the components.

The TCM is mounted inside the transmission, where temperatures remain mostly constant compared to an external-mounted module. It is small in size, which helps minimize the overall size of the transmission. The transmission and module are assembled together, so no additional connections are necessary during vehicle assembly.

TECHM
The 6T40/6T45’s transmission electronic hydraulic control module (TEHCM – pronounced “TECH-im” by engineers) contains basic software and algorithms shared among all Hydra-Matic six-speed variants, including RWD, FWD and AWD. The module is located inside the transmission, which reduces manufacturing complexity, and requires only vehicle-specification calibration to the core program. The TECHM also enables features such manual shift control and grade logic.

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## swingdoctor1952 (Nov 22, 2012)

My 2012 LTZ doesn't down shift coming off the highway exit ..It seems to stay in 5th or 6th gear and than after you put on the gas to speed up on to the highway again jumps...very strange..anybody else have this problem


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## jjducky (Oct 22, 2013)

Everyone that is posting issues sounds like the issues I had with my 2012 Focus. The tranny would do most of what was described, plus on a few occasions it would "pop" out of gear during "off the line" acceleration, like from a stoplight. Very scary trying to cut across traffic and then all of a sudden the RPMs peg the needle then it pops into gear and I catch a wheel. That combined with the dismal Sync system made me hate an otherwise cool car. My Cruze, on the other hand, has been a dream! the MyLink system could use improvement, but its worlds better than the Ford equivalent. The tranny is a thousand times better than the Ford. having owned a few different small cars over the years, I would say this is the best small car i have ever owned. And on a side note, The voice of the Sync and the voice of MyLink are the same.


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## XtremeRevolution (Jan 19, 2012)

I'll throw this out there. If someone with a 2011 Cruze is suffering from jerky or erratic shifting in their Cruze and wants to try a different fluid, I will sell you 3 gallons of Amsoil Signature Series Fuel-Efficient Automatic Transmission Fuid at $10 under my dealer cost. I am basically offering to pay one person $10 to try this fluid to see if it alleviates the shifting issues you are noticing. 

The reason I suggest it is because I've had a couple of Cruze owners report positive results with 2012 transmissions. With as little as 20k and 26k miles, the owners reported significantly improved, "night and day difference" shifting quality. Smoother, less erratic and less jerky shifting. 

Here's a quick thread with some more information about the fluid:
http://www.cruzetalk.com/forum/113-...msoil-automatic-transmission-fluid-cruze.html

If you are interested in trying it, let me know. Because I'm taking a loss here, I can only afford to do this for one person for the benefit of the forum, and it has to be a 2011 Cruze with jerky/notchy/erratic shifting. We have already reported good results with 2012 Cruzes on this fluid so I don't need anyone to try that.


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## XtremeRevolution (Jan 19, 2012)

As an update, I learned from a GM trans tech that one of the biggest causes of issues in this transmission is a rust inhibitor that was added to the sealed transmission for all Cruzes built in the 2010-2011 production year. This would cause lots of problems with shifting when that rust inhibitor would get into the fluid, which is what we have noticed.

The solution, as you would expect, is to get the fluid changed. I am told that GM has since stopped using that rust inhibitor, although time will tell how well the transmission fluid in the later part of the 2012 model year and 2013 model year Cruzes holds up.


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## Chevy Customer Care (Oct 29, 2011)

swingdoctor1952 said:


> My 2012 LTZ doesn't down shift coming off the highway exit ..It seems to stay in 5th or 6th gear and than after you put on the gas to speed up on to the highway again jumps...very strange..anybody else have this problem


Hello swingdoctor,

I can understand your concerns. Have you discussed this with your dealership? I would be happy to reach out to them on your behalf. If this is something you would like my assistance with please PM me your full name and contact information, VIN, current mileage, and involved dealership. 

Sincerely, 

Jonathan A. (Assisting Erica)
Chevrolet Customer Care


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## Christrit (Jun 23, 2012)

I reported the jerky transmission shifting and also slipping from 1st to 2nd on cold starts..... Of course they couldn't replicate the problem when their transmission tech
took it for a drive...... It's still ongoing and noticeable worse now...... Car is in the bodyshop for a little cosmetic surgery and my courtesy car is a 2011 Cruze...... My
Cruze has NEVER shifted as nice as the 2011 courtesy car I'm driving now..... On vacation in a week (for 2 weeks) and will be dropping my Cruze at the dealer so they can
have it for the 2 weeks, hopefully THEN they can replicate the problem and fix it for when I'm back.... 

This car is just ridiculous with all the problems.... They need to recall every single one of them, refund money and have a Cruze bon fire on some island....


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## 302svt (Feb 19, 2015)

2011 Cruze with 21k on it and it will not move, getting codes p2723 and p0700,


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## cvitullo (Jan 28, 2015)

just started for me, 2011 1.8 base model, downshifting from 5th to 4th, upshift to 5th, sometimes when its cold, taking off it will act like it shifted twice and bang -


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## mattillakk (Sep 27, 2015)

Yes. 2011 Cruse 6AT w/1.4L turbo

Sent from my SAMSUNG-SM-N910A using Tapatalk


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## mattillakk (Sep 27, 2015)

Hit the 50,000 mile mark.. changed transmission fluid today. Seeks like it may have helped but I'm as prone to wishful thinking as much as the next guy. I'll let you guys know what transpires after a few days of driving.

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## jpavlik (Dec 22, 2016)

Yes


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