300lbs will make a significant difference, and the different final gear ratio was done to compensate for that. yes, the 4.08 in an HHR will be better for accel than the 3.84, but that difference is overcome by the weight. but as others have stated, i believe each actual gear ratio, ie 1-5, are different between the HHR and Cobalt, where the Cobalt is marketed more for the performance aspect (ie 100% are manual) while the HHR was kind of intended as a gimmick to sell more HHRs (ie 30% manual, 70% automatic), so the Cobalt got more performance oriented gearing, while we were just decently thought out gears for a daily driver family hauler.

also, for the 121ci vs 122ci, someone just rounded their math differently, we have the EXACT same engine. there is only 1 LNF, 1 2.0L Turbo. i do believe the proper math turns a 2.0L into a 122ci.

fact of the matter is, at 300lbs lighter, better aerodynamics, and more performance tuned gear ratios, the Cobalt will always be faster mod for mod, unless the guy in the Cobalt can't drive lol.

 

rule of thumb I have always heard is .10 of a second for every 100lbs

so .3 of a second difference, not .6 imo. The Cobalt has the advantage of staying in 3rd across the line.

It's possible the transmission gearing is different, but until we find out otherwise, I doubt they are.

 

HHR SS Specs and Cobalt SS Specs.

Go about 2/3's of the way down and you will find them. Funny part is, when you determine the total ratio things get interesting. First gear is almost identical (.06 diff). Second gear the Cobalt has the advantage (.63) and third the HHR does (.21).

Advantage meaning the gear is higher numerically IE you will go through the gear faster if all other variables are the same. That .21 difference is probably why you see the Cobalt able to stay in 3rd and the HHR shifting to fourth just before the 1/4.

The .1 for 100 ratio IMHE is good for when you are around the 11 sec bracket. The weight becomes less of a factor as you have more power/go faster in the facet that it's harder to pick up .1 at 10 sec then it is at 15 sec.

HHR Cobalt
Gear Overall Gear Overall
First 3.38 13.69 3.58 13.75
Second 1.76 7.13 2.02 7.76
Third 1.00 4.05 1.00 3.84
Fourth 0.89 3.6 0.98 3.76
Fifth 0.70 2.84 0.69 2.65

Rob

 

Ah good point...

sorry, I'm usually in the 10, 11 and 12 second forums on other sites. Kind of gets stuck in your head

 

totally lost now...Does anyone know what the differential ratio is for the HHR SS with AT vrs Manual? Not the colbalt just the HHR. Also, is there any difference between the 2008 and the 2009?

 

I think the weight distribution is a factor too. I think the weight difference is a little less than 300lbs, but it is mostly in the rear. Under hard acceleration this would take a lot of traction away from the front wheels, moreso than the cobalts.

 

I haven't looked from 2008 to 2009, but there was a difference in almost every trip package for the HHR.

Just go to Chevy.com and look at the full specs of the car. The base model had the highest gear ratio


Plus I have limited slip, it didn't mention if that changed the ratio either.

 

Bingo some one gets FWD and dragging them....its were the weight is....also I believe drag is a bit of a problem for us also put your hand out the window while driving and turn it see the difference.....seat time is also a big thing those of us going faster than most have been running for a while

 

Here's the drive ratio per gear--

1st = 3.38
2nd = 1.76
3rd = 1.18
4th = 0.89
5th = 0.07

Final = 4.05:1



1st = 2.96
2nd = 1.62
3rd = 1.00
4th = .68

Final 3.29:1

 

No problem!

A few people mentioned weight ratio's. I don't have the links, but Car&Driver had spec sheets from their tests you could see. From what I remember, the HHR was 58%/42% and the Cobalt was 60.5%/39.5%.

Most of my experience at a drag strip is with a Chevelle so I understand weight transfer on RWD. I unfortunately don't understand how to utilize the weight transfer on a FWD. If someone wants to school me, please PM me.

Rob