I've got an '08 HHR SS 5-speed with LSD. Often while shifting, there's an audible "clunk" when going in to the next gear, and you can feel the clunk as well. It's easy to reproduce by sitting at idle and shifting between neutral and first gear. The LSD also whines audibly at lower speeds (just coasting in neutral with the clutch pushed in you can still hear it). There's also a grinding/scratching noise under engine braking at any speed. I've also found that it's nearly impossible to let off the gas while cruising without the car jerking a little bit, no matter how slowly I let off the gas. It feels like there's too much play in the drivetrain somewhere. The sounds remind me a lot of my old 1972 Datsun 240Z which had about 150000 miles on it.

None of the noises are really loud and shifting in general feels OK, but it makes me wonder if the car was abused a bit before it was broken in. I got it with about 150 miles on it, and there's no telling what those miles were like

 

My 08 ss makes all those same sounds too (clunk with new gear when clutch comes out and gear whine). I've read the gearbox in our car can be noisy but it's normal. As for the jerkyness I had a 02 WRX before this car and it was a drivetrain nightmare compared to this thing so to me it feels nice and tight. I bought my car with 34 miles and I've been abusing it ever since so we'll see if that's cause for you to worry down the road. So far 800 miles into mine it's handled my attempts to break it pretty good....hope this helps...

I found this on the colbalt ss site, same trans so I betting is normal on our cars.....

http://cobaltss.net/forums/showthread.php?t=118385

 

Same things happening with mine!
I just figured it was normal for this car.
Also when I start the car it makes a really funny grinding sound, any of you getting that?

SPPD

 

SPPD: When you first start the HHR SS and the engine is cold, it makes a pretty loud wooshing noise which I think is air intake under high vacuum, and could certainly sound like a grinding noise. It's very noticeable.

astropods: I too had a WRX, and the drivetrain was indeed pretty jerky, a bit worse than my HHR SS. But it didn't clunk or grind nearly as loud!

I don't mind these noises if they're just part of having a drivetrain that'll stand up to 260hp and 260lb/ft (and more with the GM stage upgrades), but these seem like metal-on-metal sounds which will eventually get worse and break something. I'm not too worried about them since the warranty should cover any problems, and the car is a blast to drive - I've put on 2000 miles in the first month, and I walk to work each day

 

My wife complains about the tranny in my SS as well. (She's never driven my Jeep!!!) While not as buttery smooth as her Civic, this thing is a dream compared to my Wrangler.
Yes, mine clunks as well and is noisy. I'll wait until she's broken in before I pass judgment. Car is Awesome to drive and I have to invent excuses to drive it (I ride my bicycle to work and have 2 other cars)

JIm

 

Noises like that should never be considered normal even if they are common for a certain vehicle/trans. Clunks mean excessive lash or backlash and the distance between gears needs tightening. It will not get better on its own.

 

I wonder if the ratio of the trans and/ or the diff/ final drive box has anything to do with the clunk that I also get from mine and she whines just like the others do to.......could be that the actual gears/cogs are slightly straighter cut and not heli/ arc cut

 

Nope. Clunking has nothing to do with ratios. Whine might be more prevalent with some gearing but my many years experience at an axle plant says clunking is a real problem due to distance and will probably deteriorate.

 

Oh...your'e talkin' 'bout back slash or whatever they call it?