Hi everyone, I don’t actually own a cobalt but after some research I plan to use the transmission from one on a project I’ve been designing. I hear the cobalt SS has a very strong manual transaxle. Any information on the dimensions, mounting surfaces, variations by model, and any issues it may have would be very useful.

 

Depends on your power levels, which final drive you use, and what kind of weight/load it'll be under.

Whoever told you this is likely talking about the LSJ (05-07 SS Supercharged) and the LNF (08-10 SS Turbocharged) transmissions. The LSJ's had a 4.05 final drive... the LNF's had a 3.85, I think... somewhere right around there. You can also get a 4.45 final drive, but that wasn't a stock option. Other than that, they're essentially identical transmissions. They're getting to be rather rare though, so the prices are jumping up. The gearing is pretty long, and the RPM drop from 1st to 2nd gear is pretty stupid. There's likely to be better options out there. Honestly, I'm betting you'd be better off using a VW GTI transmission. There's more of those cars out there, the transmissions are also pretty damn good (same essential design for the past 20-30 years), and the aftermarket availability is thicker.

But for the Cobalt transmissions, under 400WHP, they're pretty stout. Into the 400's, and some people have problems; more so if you have a lot of torque and the longer final drive.

 

the low end torque won’t be a problem and the car will be lightweight, but I won’t know the horsepower output as the engine configuration isn’t exactly “common” 😏, however it could very possibly exceed 400hp...

 

What is this going into?

 

The issue with higher power levels is that the bearing supports for the shafts leave 3rd gear a little vulnerable. So with elevated power levels and the longer final drive (putting more load on the transmission/engine), what happens is that the shafts start to deflect. So a long, powerful 3rd gear pull will cause the shafts to deflect a bit, and then either they deflect enough for the tips of the teeth to break off, or you release they power and they crash back together, breaking the tips of the teeth. Some people have run high power and not had issues... others have not been so fortunate. If you're in a much lighter vehicle (like an Atom type vehicle), then that may work to your advantage.

Like I said before... a lot of these things are getting hard to find though. ZZPerformance used to offer 4.45 swapped transmissions for sale, with tighter bearing clearances and a few other things... but they stopped selling them for one reason or another.

I know they're out of stock of the LSD transmissions, but the non-LSD is still available. https://zzperformance.com/collection...5-transmission

One of the options that some people swap to is either the F23 (common in older Cavaliers, iirc) or the F40 transmission (found in Saabs, G6's, and Buick Regals). The F40 is a 6 speed. https://zzperformance.com/collection...0-transmission

 

does the f40 have an open diff or an LSD?

 

Saab f40 comes with or without lsd but they are incredibly hard to find and will more than likely be used .

Regal f40 doesnt come with lsd (not sure if they offered it with lsd but one can be found and installed but they are pricey) non lsd can be found for about 500 plus shipping last time I saw

 

https://www.ebay.com/itm/Cobalt-SS-5...AAAOSwj39cye8E

 

My stock MU3 trans NON LSD worked great up until 150k miles. That's when she developed the 2nd gear grind. Bought the car new in 2005 and installed GM stage 2 kit when she had 500 miles, then the GM stage 3 kit at about 1,500 miles. Still running the stock axles from the factory almost 15 years later.