# 6M Shifting



## Mattman (Nov 2, 2019)

Hi, I posed this in my into but I wanted to make sure I posted in the proper section as well. Just a recap, I recently bought a 2016 LT 6M. Its a nice car but I find the shifting on it to be lacking... a lot! I've owned other manuals, so I know how to shift. I never had a problem before but this car is very different. I don't know if its normal for this transmission or if I have something wrong with my car. Almost all info I find is about the Gen1, not Gen2.
Anyways, here's whats going on... as best as I can describe it.

N -> 1 can be rough.
1 -> 2 is very rough and clunky and if I don't get the right speed and/or RPM exactly, its a bad shift.
2 -> 3 is a bit hard. It's like its not the gears are synced up. I find 3rd pulls itself into gear as opposed to a smooth glide into the gear.
3rd is unstable, I mean the shifter moves quite a bit when cruising or pushing in the clutch.
3 -> 4 is iffy, sometimes rough, sometimes smooth. 4th also pulls itself into gear.
4 can sometimes unstable too but not as bad as 3rd
4 -> 5 -> 6 all shift super smooth and solid.

Downshift is pretty much the same.

My hope is to:
1. Change/flush the transmission fluid. I've read about a specific product, Amsoil Synchromesh or GL4. I'm lost as to which one I need OR if I even need it OR just let the shop pick whatever they decide?

2. I'm thinking about getting the M32 Short Shifter Q2-Shift

3. Removing the CDV (if possible).

I live in an apartment, in Kitchener (southern Ontario) and its November - so I'll be letting a shop do the work lol

Anyways, any help anyone can give would be appreciated. I don't want to wait too long, just in case there is something wrong with my car. If what I need/want to do is right, I can just print off this thread and show the mechanic.

Thanks


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## 17Hatch6MT (Dec 28, 2015)

I have a 2017 with a 6MT. It's certainly a bit notchy when cold. I especially notice this in 2nd and 3rd. A lot better when warm. Yes, try the Amsoil fluid, the multi-grade one that's good in the cold. This fluid worked wonders on my 2001 Nissan's shifting. I intend to go to that, soon. My car only has 16,000 miles so it's not necessary at this time.

As far as the shifter moving when you're on & off the throttle... No, I haven't seen that. This is a cable linkage, right? I'd look for adjusting the linkage, making sure the cables are attached to the car where they should be, checking the engine and front suspension mounts.

I've had an odd assortment of new cars over the years, all manual transmission. My 1986 Renault Alliance 4 speed, I damaged the 2nd gear synchronizer by forcing it during break-in. After that one episode, engaging 2nd gear was loose when the car was warm, and could be a bit grindy if cold or an aggressive downshift. My '89 Honda, 2nd gear had similar damage probably caused by a test-driver before me. My '01 Sentra 2nd gear was similarly damaged, probably after my mom took it for an unaccompanied spin (I'd borrowed her van to move some stuff) & forced 2nd gear. I drove the Honda and Nissan to very high mileages without trouble (no popping out of gear), and sold them on to people I knew who continued to drive them much farther also without trouble, so I'd not worry about an easy engagement (is this your 2nd and 3rd gear trouble?), except to take care with oil changes and driving habits not to stress it further.


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## Mattman (Nov 2, 2019)

I'll be doing the transmission fluid regardless. I bought this car used and I have no idea how the person(s) before me drove it. It definitely feels like theres a lack of syncing with the gears. Getting the fluid changed will at least show what condition the transmission is in ie: colour, smell, metal debris etc.. 

I did a search on the Amsoil webpage and they have no recommendations for the manual Cruze, only the auto. I guess I'll just have to get the shop to use whatever they use.I'll get them to take a look at the linkages too.

Thanks


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## Spoolin6Spd (Jun 19, 2017)

Send XtremeRevolution a pm I got my amsoil trans fluid through him and it was super easy. Also if you’re at all handy, it’s not hard to change yourself. I’d recommend a cdv delete and amsoil fluid. I have a 1st gen and I’m not sure if they make the part for 2nd gen, but Badnewsracing sells a clutch accumulator bypass valve mod that really helped the shifting in my car. 


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## Mattman (Nov 2, 2019)

Hey thanks for the info. I really appreciate it... once I figure out how to PM someone, I might give it a shot. 

You said you have a gen1 but mines a gen2. As far as I know, its the same M32 transmission but I'm sure there are subtle differences. This is kind of what I was referring to, a lot of responses and help on this forum mostly reference the gen1. Like the CDV valve, as far as I understand is much harder to get at in a gen2 then in a gen1. I read somewhere its in the slave. 

I'm handy enough but as I stated in my (two) posts.. its November in southern Ontario aka getting cold and snowy + I live in an apartment so I don't have a private driveway or garage to do the work. If I could, I would. It would save me tons of $$$ lol

What I need to know is specific to the Gen2.... 
Exactly what Amsoil fluid do I need? 
Is the ACDelco just as good? (as per the owners manual)
Is the Q2-Short shift worth it?
Can the CDV be removed easily enough to avoid paying exorbitant shop labour fees?
Is there anything else I can do to make it shift better? I read somewhere (on here) about adjusting the linkage (sonic tsb has the diagram).


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## 17Hatch6MT (Dec 28, 2015)

Huh... No recommendations on the Amsoil website for this transmission. 

I think this needs a 'GL-4' and not a 'GL-5'. The GL-4 protects brass synchronizer rings, GL-5 can eat them. I thought this was the recommended product:
*Manual Transmission & Transaxle Gear Lube 75W-90*
... but I can't find any recommendation for any Cruze MT on the Amsoil site. I wonder if it's a case of having to pay GM for a license to recommend it? Hope someone smarter about this can answer.


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## Mattman (Nov 2, 2019)

That's the fluid I read about on this forum and the syncromesh. I checked out the site and that's what I found too - no info.

When I search my owners manual, I get GM part #19259105 which shows me ACDelco gl4 70W fluid online. 

Will the amsoil 75W-90 work since it's gl4 compliant? and will it be good for cold Canadian winters?


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## 17Hatch6MT (Dec 28, 2015)

The Amsoil product I named, says it performs well in cold temperatures. It did work well in my Sentra.


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## 17Hatch6MT (Dec 28, 2015)

From your original post... could the clutch not be disengaging completely? Some people have reported trouble with the slave cylinder.


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## Filadog (Feb 18, 2019)

I agree with 17Hatch6MT...judging by the symptoms you stated, the pressure plate is not fully disengaging.


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## Dealer1 (May 5, 2019)

It sounds like a clutch problem. My sons 2018 was in shop for 3 months for clutch master and slave cylinder


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## Mattman (Nov 2, 2019)

I'm going to make an appointment with the shop today and I'll either direct them to this thread/forum or I'll just print this off and show them when I go in.

I really appreciate all the help/responses. Hopefully it makes it easier to pinpoint any issues I might have. I'll let you all know what they say.


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## Mattman (Nov 2, 2019)

Oh, one thing I forgot to ask... is this normal for this car or should I add this to the list? lol

Sitting idle, transmission is in neutral (not in any gear, shifter is in the middle position). When I push the clutch pedal in, the engine RPM's jump up quite a bit before coming back down. 

I understand how MT work (clutch plate, flywheel etc...) but this seems really weird to me that pressing the pedal in would change the engine RPMS when its sitting in neutral. Maybe I really don't know manuals work after all these years but I've never had any of my other cars ever do this. 

I'll gladly give up some MPG for a solid transmission... I really miss my '93 Sunbird GT. That car was a beast lol
Once I get this all figured out, I'm sure this will be a fantastic (and hopefully fun) car to drive. *fingers crossed*


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## 17Hatch6MT (Dec 28, 2015)

Gosh... something is really messed up in there. Lots of drag when the clutch is engaged in neutral? Now sounds like a transmission problem? I'm just shaking my head. Hope you find an honest and competent shop.


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## Mattman (Nov 2, 2019)

Funny part is, there were a couple of other Cruze's on autotrader that I had my eye on. The dealerships weren't in the mood to negotiate prices. So I waited, found this car and it checked all the boxes so I went for it. Even test drove it, seemed fine but then... I was excited to get back into a manual and clearly didn't pay enough attention. 
The other cars are still on the lots and they lowered their prices... lol

The jokes on me I guess.


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## Taxman (Aug 10, 2017)

Lots of people on this forum have had their trans removed and the clutch hydraulic cylinders replaced under warranty. 

And I'm getting the idea that the chances of a diesel flywheel lasting 200k miles are pretty close to zero. 

Are the LE2 flywheels dual mass?
Are they holding up better than the diesel DMFs?

The DMF complaints remind me of the 928 horror stories of 40 years ago: 
"Buy the auto, if you get a stick you'll need a $1200 clutch job in 10k miles."
"$1200??? Why so much?"
"Because they replace the flywheel too"
Decades later, I learn that Porsche 928s weren't having low mile clutch failures, they were having low mile DMF failures.


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## jblackburn (Apr 14, 2012)

Mattman said:


> Oh, one thing I forgot to ask... is this normal for this car or should I add this to the list? lol
> 
> Sitting idle, transmission is in neutral (not in any gear, shifter is in the middle position). When I push the clutch pedal in, the engine RPM's jump up quite a bit before coming back down.
> 
> ...


This is normal, the ECM gives you a rev bump to make starting off with minimal throttle input easy. 

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## jblackburn (Apr 14, 2012)

Taxman said:


> Lots of people on this forum have had their trans removed and the clutch hydraulic cylinders replaced under warranty.
> 
> And I'm getting the idea that the chances of a diesel flywheel lasting 200k miles are pretty close to zero.
> 
> ...


Yes they're DMF and basically all DMFs are junk. They do make power transitions a heck of a lot smoother though. 

The DMFs had a high failure rate on the 1st gens and I've definitely read about a lot on the diesels, but fewer in the 1.4T Gen 2. 

DMFs do NOT like a lot of torque at low RPM it seems. Which defeats the whole purpose of having a diesel or torquey gas turbo motor. 

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