2010 Transmissions

DanPerryy

Well-Known Member
My donor has an automatic transmission. In rethinking, (I drove both and AT and a MT and they are both equally quick) I think if I were to do it again I would go with the MT. The reasons:

Reason 1:
Being able to change the final drive ratio. In the AT the final drive ration is determined by a planetary reduction connected to (part of ) the the differential housing. I doubt that we will ever find alternate ratios available.

I driving both the AT and MT cars I felt they were both "tall geared".
From the service manual there are 2 different manual transmissions for 2010 Cobalts. They call them the M86 and the MU3. In both cases the final drive from the MT is transferred to the diff through a set of gears where there are at least 3 different gear ratios available. However I think all Saturn Vue and HHRs use the M86 transmission. The M86 transmission has no LSD factory option. I think these are all interchangeable but not interchangable with the MU3 transmission. Not positive, but I am continuing to look into it.

Personally, I have little or no desire to have a top speed of 130+ MPH in my Goblin, if I want to go fast with wind in my face I would get another Ducati, What I want is to get from 0-100+ in a hurry. this is so I can get milk at the grocery store and get back home. A larger final reduction ratio would make sure the milk does get overheated on the short time to get back home.

Reason 2:
Having a LSD. In going someplace quickly (getting milk) there are a lot of curves and I would like to slide around them. A limited slip differential would be a great help.

I know from the manual the MU3 transmission without a LSD can be changed to a LSD. The manual shows both on the same page stating that they replace the entire diff (case and spiders) as a non-serviceable assembly. The ring gear for the M86 from the manual "looks like" - correction 4/21 - I think they have different hole patterns - the ring gear for the MU3, same holes for mounting the diff cage. However the output shaft of the transmission for the M86 has the equivalent of the pinion attached to the shaft itself. While the MU3 has a separate pinion gear on the output shaft.
 

TomsGarage

Active Member
Hey Dan,

That was my thought process too, and I ended up going with turbo SS donor. One thing to note about the LSD, not all of the SS come with the LSD. It was an option, and you can see if it has it by looking at the build codes in the trunk. Another thing with the LSD is that apparently it can make driving at the limit more dangerous, at least according to Lotus.
 

DanPerryy

Well-Known Member
I knew the LSD was an option. I think there is an aftermarket LSD that works too. The LSD works only in the MU3 transaxle. The MU3 is an Saab units. The M86 - not sure if any SS's have this transmission - does not have an LSD option. The MU3 and the M86 have different bolt patterns on the ring gear.
 
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