I see that the final drive ratio for the auto is 3.29 while the 5 speed is 4.17. Why is the 5 speed ratio so high. The transmission ratios for each in high gear are about the same. I guess this is geared for the drag racer and limited fuel economy/engine life. Sorry to see.

 

I'm no car genius but doesn't the final drive ratio need to be shorter in the automatic since it has 1 less gear?

 

Actually no (especially since the high gear ratios are basically the same), and the automatic ratio is taller not shorter.

 

Where are you getting your info?

Type: F23 5-speed manual Hydra-Matic 4T45-E 4-speed automatic
Gear ratios: (:1):
First: 3.58 2.95
Second: 2.02 1.62
Third: 1.35 1.00
Fourth: 0.98 0.68
Fifth: 0.69 –
Reverse: 3.31 2.14
Final drive ratio: 4.17:1 3.91:1

 

I think you got your highs and low backwards most small 4 banggers have lower gear ratios to make the car perform better.As far as the 5sp geared for drag racing and less mpg you got that backwards as well.I run my 5 sp at less rmp at low speeds than anyone can with an auto you have no control over the rpm of an auto.Truth is the 5 sp is faster and is better on fuel and has no impact on engine life.

 

The 4.17 is a lower ratio.. (you can call it high, it depends on what you mean). The lower the ratio (numerically higher) the better acceleration the car is supposed to have compared to the same car with a higher ratio.

 

2008 HHR SS Frequently Asked Questions :

https://www.chevyhhr.net/forums/hhr-ss-45/2008-hhr-ss-frequently-asked-questions-9989/

Transmissions
GM Powertrain Sweden F35 5-speed manual / Hydra-Matic 4T45 4-speed automatic
Gear ratios: (:1):
First: 3.58 / 2.95
Second: 2.02 / 1.62
Third: 1.35 / 1.00
Fourth: 0.98 / 0.68
Fifth: 0.69 / –
Reverse: 3.31 / 2.14
Final drive ratio: 4.17:1 / 3.29:1

and


GM Technical Data on HHR SS

https://www.chevyhhr.net/forums/hhr-ss-45/gm-technical-data-hhr-ss-12374/

http://media.gm.com/us/powertrain/en...08/08truck.htm


2008 Hydra-Matic 4T45 Transaxle( MN5 )
Final Drive Ratio: 3.05, 3.29

2008 GME Sweden F35 ( MU3 )
Final Drive Ratio: HHR SS - 4.05





If these numbers are right, the engine with a 5sp will turn about 1/3 higher revs at the same speed in high gear. That's bound, after 100,000 miles, to have an effect.

 

Didn't notice you were talking about the SS, my bad. Probably cause the auto is too wimpy for the motor. As you could see from my post, the ratio's for the standard are the same, including all gears. They had to detune the motor for the auto, looks like they put in a set of highway gears to boot. This will not hurt the manual or the motor. Looks like the auto will run a slightly less RPM.

Higher gears and a lower top speed, go auto owners.

 

Anyone know the ring and pinion gear ratios in the differential? Looking at the final drive ratios the differential gears are different between the manual and auto.

 

It's my understanding the final drive ratio for a rwd is the same as the ring an pinion ratio for a rwd.

Just no ring and pinion for a fwd.