FAQ: 2nd Gear Grind & Possible Solutions

Updated: 10/01/15

The m32 transmission in the 1.4 sonic and cruze has a notorious grind between 1st and 2nd gear @ higher rpms. It doesn't seem to be any different between the variations we have here in the USA. MZ4 (sonic & cruze), MR5(rs sonic), MZO(eco cruze). (1.8 5 speed models are not affected in this as its a different transmission)

There seems to be a whirlwind of information as to what is actually happening inside the gearbox to cause this, anywhere from a low factory fill of 1.5qtz, to plastic fork ends, to narrow left gate or the excited shifter.

In this article I'm going to attempt to explain each of these theories, and attempt to explain some solutions that have worked for me any many others in the community. Please keep in mind these solutions will cost you money, but I feel like if you catch them early enough your preventing a total transmission failure and if your out of warranty could save your from having to fork out for a new trans.

A lot of this info will be compiled from the Sonic Owners Forum and this link http://www.sonicownersforum.com/forum/transmission-discussion/2626-second-gear-grinding-remedy.html I want to give special credit to Vincent Faltis for all his info and specifically the Cable Adjustment info in this link that I will also post here.

While other info is just stuff I read or heard on the Facebook pages. I do not intend for any of this information to be my own, so if something I post was something you said feel free to email me and I will give you credit here. This is basically an attempt at putting the info in a easy to find place that will go further into explaining the solutions.

Also please ignore any grammatical errors and lack of punctuation its not my strong point, and I am well aware of that.

Possible Reasons the grind happens:

Low factory fill:

The manual states the fill is 1.5 qt. while the UK versions of the manual specify 2.37 liters which is 2.5 qt. I don't know if this was done to cut cost or because this car is technically an economy model and they didn't figure people would be redlining the car.

Solution:
Drain and Fill 2.5qt GL-4+ 75w90 Gear oil. Redline, Royal Purple, or Amsoil equivalent. The important part is GL-4+.

Plastic fork End:
So the ends between the gears on the forks are plastic.

Solutions:
While there isn't much we can do to change the fork ends, we have a few ways you can avoid it.

1. Cable Adjustment:
The cable alignment is off from the manufacture. To do the cable adjustment follow the below Service Bulletin. This was something I did after we changed my shift knob which knocked my cable adjustment out to the point I couldn't put the car in reverse. I don't know if this actually helped, but it seemed to make a difference, and a lot of people have said the same thing.

2. Shifter Bushings:
Sold buy a variety of vendors including BNR, DDM, ZZP. At the time of writing this article, I am currently using the BNR shifter bushings, but had the DDM before hard, I personally feel like the BNR shifter bushing lead to a slightly stiffer feel. This made a noticeable difference in the 2nd gear grind but I still could seem to find it every once in awhile.

3. Short Shifter:
There are currently two short shifters available. mTech, and DDM while the mTech is technically the only one available for 13+ sonics. ddm does have optional weights for the 12 model, 13+ model is currently in development but has been for over a year. I am currently running the mTech short throw 13+ model and I absolutely love it. With this and Bushings the chances of the second gear grind greatly diminished, but wasn't completely resolved.

4. Cable Clamp(s):
There are several companies that offer a cable clamp, BNR and ZZP, both are similar in style but I have only ever used the BNR cable clamp. This makes a dramatic difference in the entire feel of the shifter, more so than just about anything else listed so far. The problem with this solution is you cannot currently run both the short shifter and a cable clamp. The cable clamp feel is so great, I have contemplated switching to it instead of the short shifter, but Allen Payne is working on a solution to which I will keep you updated. Allen has successfully modified the BNR cable clamp to work with the Mtech short shifter! Together, I have not gotten the second gear grind at all! So Far So Good. We have also added an additional clamp to the top cable, and you can still feel a noticeable difference with it. The car feels completely different in the shifter anyways. Solid positive clicks into each gear minimal play.

Having 3 of the four items done I can say that I still once in a blue moon manage to grind 1st to 2nd, but I can't sum it up to the trans being at fault or my clumsy feet to hand coordination. With the success everyone else has I'd say it probably me at that point. Pretty sure its now not a issue since I now have everything you can do to the shifter. I will update if I can manage to get it to do it anymore.

Narrow Left Gate (excited Shifter)
One thing I did notice when I first had the 2nd gear grind was how I was shifting... Often times I was in the heat of the moment "banging gears" if you will and BOOM it happened. What I noticed while trying to recreate the issue to also resolve it was that, when I was excited I would pull towards myself and back. In other words i was hugging the left gate.

Solutions:
I have retrained myself to pull straight back. Being that I have never had this issue with any other car, I can only assume that it must be more narrow between the left gate and the fork ends for it to be an issue on this car. I'd be interested to know if the RHD Barina / Aveo Owners have this problem considering they wouldn't be hitting the left gate at all being on the opposite side of the car pulling more towards 4th.

Update:
Zachary Kell, brought it to my attention that seating position could have something to do with it, he said he wasn't sure if it was allowing him to fully engage the clutch or maybe it allowed him to better align his arm for a straight back pull..

Joshua Osiris said. In my cruze I noticed a grind at about 10 to 12 mph in the middle of 2nd gear took in to dealer to check transmission and they didn't find a problem.. Did a bit of research and I guess the abs can cause that to happen upon driving the car when it's cold. But only when you first start, obv if the grind persists everytime you go into 2nd it's unrelated.

Anyways feel free to comment or email me with other comments or solutions, I'd be happy to add them or change information that may not be exactly correct.