Yep going from 4th to 2nd will really work the syncro's, but using that double clutching you mentioned, it virtually doesn't use the syncro's. Whenever I downshift, I always double clutch it. Old habits die hard, I guess.

 

I was just sort of "fishing" for ideas about the strange behavior of my HHR's transmission. I am 62 years old and I have had a driver's license for 45 years and I have owned a lot of standard transmission vehicles, so abuse and lack of experience are not factors in the occasional gear grinding.

I have been deliberately eliminating downshifting into 2nd gear unless I am moving at less than 20 mph. That seems to have eliminated the problem. If I am coasting at over 30 mph and have no reason to slow down or downshift, and I attempt to put the shift lever into 2nd gear, I will detect interference until I have slowed down considerably. There are absolutely no other problems with shifting or clutch slippage. It's just that occasional grinding when downshifting into 2nd, which I have hopefully eliminated by way of speed restriction.
Thanks for the input.

 

My 07 Started doing this same thing around 54k miles after letting an ex g/f of mine drive the car. After another 2-3k miles it got really bad and the 2nd gear synchro's had to be replaced.
The car was covered under the 100k power train warranty and didn't cost me anything.
The transmission tech actually seemed competent and told me that most of them do this in both the HHR's and the cobalts when people are driving them that should not be driving manual transmissions and he does alot of these repairs.
Ive put 17k miles on the car since the 2nd gear synchro replacement with no more issues at all,even under constant extreme abuse by me.
However my HHR has made it very clear it does not want anyone driving it but me.

 

Unfortunately, today, there are fewer and fewer drivers that can drive a manual transmission, or should. I had new tires put on my 2007 LS, and when the kid went out to the car to pull it in, he looked inside, closed the door and walked back inside, as he passed me, said 'I don't drive cars with a stick shift'. I was grateful he didn't even try, frankly. I have been driving stick shifts for over 50 years, so its second nature to me, I don't even think about it, but not to todays kids, apparently.