2012 6spd manual sound like a rally car transmission or something at highway speeds

[Durdenss]

Not sure if this is normal, doesnt seem like it. It shifts completely fine except it can be a little hard to shift when extremely cold. Doubt the tranny fluid has ever been changed and it has 78k miles.

 

[Papasonic]

There should be very little noise from the manual transmission. Some owners have had some internal transmission bearing failures, resulting in the trans being replaced. Some believe that the quantity of lubricant was insufficient to lubricate a specific shaft and bearing in the trans case. There are a few threads about this on this Forum, and on the Cruze Forum too.
The hard shifting when cold is also an issue, and is often related to the type/viscosity of lubricant in the transmission; again, there are a few related threads on this issue also.

 

[TheGreenDragon]

I think it was an issue with the M32 starving the 5th/6th gear bearing of lubricant due to an internal design flaw. I believe I read somewhere that they updated the transmission on newer models to fix this fault.

 

[Papasonic]

I think it was an issue with the M32 starving the 5th/6th gear bearing of lubricant due to an internal design flaw. I believe I read somewhere that they updated the transmission on newer models to fix this fault.

And the consensus is; to prevent this failure, is to overfill the transmission with lubricant. The threads that discuss this issue also recommend the quantity of lube, and the type/brand.

 

[cuartz7o]

And the consensus is; to prevent this failure, is to overfill the transmission with lubricant. The threads that discuss this issue also recommend the quantity of lube, and the type/brand.

Didn't have this problem but switched 3 weeks ago to amsoil Synchromesh and filled up to 2.5qt. Takes 20 min and all you need is a long funnel, 8mm hex socket (fill plug) and a 10mm hex socket (drain plug).

Sent from my SM-G925T using Tapatalk

 

[Natesriv]

Mine sounds like a very fast running sewing machine at highway speeds and cold weather. Drives fine though...

Are we sure it's an 8mm HEX head and not a T-50 torx? Anyone have an unmolested pic of one not done yet?

 

[Tormach]

It is a 8mm hex, plan on doing this in the new few weeks when weather is alittle warmer.

Reference from the cruze forum and also a diagram i found online (cant find the link).

How-To: Change the Manual Transmission Fluid

 

[Natesriv]

top nut is a PITA to get off, I had to remove the car's PC right there by the battery. 3 big plugs... then it's a bit of a arm twist to break it free. Once it breaks, it's an easy spin off...

 

[Durdenss]

nvm.

 

[humphrey111]

Mine has the whine that is wheel speed dependent. It used to start around 30mph and get higher pitched as speed increased. It was worse when it was cold.

I changed fluid per some thread around here and it didn't really help. Assuming the damage was done.

Now it's getting worse and I am looking for a salvage to swap in

Read on some European sites about the M32 and it appears the speed dependent whine is from a pitted pinion gear. Probably due to Chevy using lighter weight fluid and less than the recommend qty of fluid.

I have 112k miles on my '12 sonic by the way. I figure the clutch could probably be replaced anyway so there's that...