[MP81]

Ours hasn't done it at all since summer, and our PT warranty is done in May (wonder if I can get a GM extended PT warranty or anything before then).

The car has been at the dealer since Wednesday afternoon to replace the passenger halfshaft (ripped boot) and I haven't received even a call that it would take longer than the day I expected - maybe two if they had to order the axle, since I highly doubt they had a CTD axle on hand, but it should be a quick replacement, as it's just a halfshaft.

My buddy jokingly asked "what did they break?" - I truly hope they broke the transmission.

 

[MP81]

Bumping this back up, as the weather has every-so-slightly begun to remember it's not winter anymore.

And with it, means the transmission has become somewhat problematic again. Doesn't seem to be doing the neutral slam just yet, but it is making for some extremely violent downshifts. If I were to guess, on the 3-2, based on the speed my wife was going when I was in the car with her.

I still have the borescope from AutoZone that I rented to find the pintle cap that conveniently fell down into the intake port of my brother's 3100 which I had just replaced the gaskets on (was reassembling the vehicle at this point, so the lower intake was on, and I was not taking it back off), so I am going to utilize that to have a look underneath and see if the lines are leaking again or...hopefully...the case is leaking at the seams.

The latter would be most beneficial, as that means trans replacement - something that needs to happen soon, as PT warranty is up in about one month.

 

[BDCCruze]

Since almost new mine has sometimes downshifted hard. I believe these are dual clutch transmissions. That means it attempts to predict the next gear since it is basically an automatically shifting manual. If it thinks you are going to accelerate but you actually brake, the way it downshifts will be jarring.

For example, if you are in 2nd and accelerating it will prep 3rd. But if you suddenly brake it has to go back to 1st where it was ready to go into 3rd. This behavior makes predictable shifts very smooth and improves fuel economy, but does have some downsides.

 

[jblackburn]

Since almost new mine has sometimes downshifted hard. I believe these are dual clutch transmissions. That means it attempts to predict the next gear since it is basically an automatically shifting manual. If it thinks you are going to accelerate but you actually brake, the way it downshifts will be jarring.

For example, if you are in 2nd and accelerating it will prep 3rd. But if you suddenly brake it has to go back to 1st where it was ready to go into 3rd. This behavior makes predictable shifts very smooth and improves fuel economy, but does have some downsides.

Traditional torque converter automatic.

Just crap programming.

 

[BDCCruze]

Traditional torque converter automatic.

Just crap programming.

Oh hmm, according to the Wiki article "The shifting of gears is managed by a sophisticated computer programme which oversees a clutch-to-clutch actuation. Gear changes are accomplished by one clutch engaging the instant the clutch from the previous gear disengages." Of course Wiki isn't always right but to me that sounded like dual-clutch.

Anyways, thanks for clarifying that.

 

[jblackburn]

Oh hmm, according to the Wiki article "The shifting of gears is managed by a sophisticated computer programme which oversees a clutch-to-clutch actuation. Gear changes are accomplished by one clutch engaging the instant the clutch from the previous gear disengages." Of course Wiki isn't always right but to me that sounded like dual-clutch.

Anyways, thanks for clarifying that.

Not sure how many clutches are in the Aisin in the diesel specifically, but most automatics these days like the 6T/9T GM transmissions have a bunch of clutch plates internally to control changes between certain gears, and a series of solenoids that activate those clutches. They also use the torque converter in between shifts as another sort of clutch to ease shift shock between gear changes. These are traditionally slower to change gear than DSGs, but are much smoother in low speed and stop-and-go driving.

The clutch plates are on the left side of the image for the 6T40 - quite a few more than just the two found in a dual-clutch.

A dual clutch is more like a manual transmission setup controlled by a computer - more commonly used in performance-oriented cars (VW GTI, Porsche PDK, exotics) for their quick gear changes, but most American drivers don't like them because they're jerky and clumsy at low speed. The cars I've driven with one - Hyundai Elantra Sport, Mercedes CLA, and even the VW GTI (Mk7) - are terrible in traffic or creeping forward on hills. Odd gears are shifted by one clutch; even by the second, so it's much quicker to change gears.

 

[Aussie]

My 2012 Holden Cruze diesel uses a 6T45 transmission which is a stronger version of the 6T30/40 transmissions. I have the full specifications, but this part explains the difference. The 6T45 is also used with the 1.6T engine.

The primary difference between two variations of the six-speed automatic transaxle being the 6T45 has greater torque handling capability. The output chain is 1.25-in wide in 6T45, versus 1-in wide for the 6T40. The input gearset of the 6T45 uses fivepinion gears, versus four pinions for the 6T40. In addition, the case of the 6T45 is slightly larger and includes a heavier ribbed case for strength.

 

[Aussie]

This explains how the 6T transmissions work.

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.

 

[MP81]

Traditional torque converter automatic.

Just crap programming.

Yeah, I've never been impressed with the AF40-6 in this car, but when we first got the car it was, if a little clunky. I've always been impressed with the calibration focusing on actually downshifting and engine braking without requiring you to slap it over to manual (unless you want more), but this 3-2 slam is new.

I took a peak underneath over the weekend and it doesn't seem like the lines are leaking (again, yet), but I would sure love to see some weeping at the case split - as that's pretty definitive of "replace it now".

 

[MP81]

I'm wondering...does anyone have the specific transmission fill procedure from the service manual for this car?

If I recall, the Chilton manual stated that after the check plug drips at a very-scientific rate of one drip per second, to close the check plug, turn off the vehicle, and add 0.4L of trans fluid.

However, "AutoMate" is what I have access to now, and it does not state anything about an additional 0.4L of fluid.

It has me curious - could all these issues be due to too much fluid. It was getting extremely bad sitting in a 15 minute traffic jam in 90 degree heat last Thursday, to the point where I had to leave it in manual mode so it wouldn't shift to neutral - one time I did that, it still slammed into gear after a second or two of me moving it over to manual mode.

It was also getting real jerky on the one downshift on Sunday, and that was right away on a cold start, when it was not nearly as hot out - so that's obviously not temperature dependent.

 

[MP81]

Bump! I feel like I remember seeing something somewhere, but cannot remember where.

 

[oreo382]

I remember reading something about the wrong length of drain tube in the trans,hence the need to add an extra 0.4l after it stops dripping.Maybe they corrected this and hence the AutoMate difference.I wish I could remember where I read that but I do remember it.

 

[boraz]

I'm wondering...does anyone have the specific transmission fill procedure from the service manual for this car?

If I recall, the Chilton manual stated that after the check plug drips at a very-scientific rate of one drip per second, to close the check plug, turn off the vehicle, and add 0.4L of trans fluid.

However, "AutoMate" is what I have access to now, and it does not state anything about an additional 0.4L of fluid.

It has me curious - could all these issues be due to too much fluid. It was getting extremely bad sitting in a 15 minute traffic jam in 90 degree heat last Thursday, to the point where I had to leave it in manual mode so it wouldn't shift to neutral - one time I did that, it still slammed into gear after a second or two of me moving it over to manual mode.

It was also getting real jerky on the one downshift on Sunday, and that was right away on a cold start, when it was not nearly as hot out - so that's obviously not temperature dependent.

HOW TO: Service "Lifetime Fill" Tranmission...

HOW TO: Service "Lifetime Fill" Tranmission fluid for Diesel AW AF-40-6 Transmission There seems to be quite a bit of apprehension in performing any kind of service on this transmission in our Cruze diesel that is labeled a "lifetime fill" by GM but has a 50k severe service schedule in many...

www.cruzetalk.com

thats for the transmission itself, taken from other car forums that have this trans

i think the actual instructs from the fsm are in there, i remember somone posting it at some point.

you are sposed to do the fill check when the atf is a specific temp....75degrees iirc, but im sure its in the link

 

[MP81]

I think I need to get this car raised up a bit, and check the trans temp with the biscan app this time, and ignore the 0.4L extra fluid that I had seen, wherever it was, as it appears we do not need the extra addition once it reaches the super-scientific drip rate of ~one drip per second. All these issues literally could just be from fluid foaming from too much.

I just hate pulling that aeroshield off so, so much. Almost all the clip centers that you pull out have broken so you can't use a panel puller tool under to pull them out, so I guess pliers it is...

 

[revjpeterson]

I think I need to get this car raised up a bit, and check the trans temp with the biscan app this time, and ignore the 0.4L extra fluid that I had seen, wherever it was, as it appears we do not need the extra addition once it reaches the super-scientific drip rate of ~one drip per second. All these issues literally could just be from fluid foaming from too much.

I just hate pulling that aeroshield off so, so much. Almost all the clip centers that you pull out have broken so you can't use a panel puller tool under to pull them out, so I guess pliers it is...

I'm considering just leaving the aeroshield off once I do my delete next week. I've found when it's off, I can drain and fill the transmission and pull the level check plug without lifting the car, just by laying on my back in front of the left-front tire and reaching my arm underneath. You can't get a good view, but as long as you know where it is already, and know the size wrenches you need, it's within reach.

 

[RacerMike7]

Yeah, I'm not sure what the dealer would replace - whether it be the solenoid or the whole trans.

Putting it in manual mode makes the problem disappear entirely.

My 2014 CTD started the slamming into 1st gear just recently. 135,000 on vehicle. Its so bad I thought I was rear ended. Completely goes away when in manual shift gate. Fluid level is fine. Anyone figure out how to disable solenoid?