Wonder if anyone could tell me what the rpms of the 3.82 are at say 70? I have a 2009 cobalt ss and I'm pretty sure I have 4.05 gears in mine.

https://www.cobaltss.net/forums/driv...o-poll-135389/

According to this thread (post #4) my rpms at all speeds match to those of the 4.05 transmission. Just wanted a comparison to be sure.

 

2580 at 70

 

So the rpm difference between both gears is only 20rpm?

 

Here's the real answer.

 

That's 3.82 gears?

 

4.05

Just look at the tag on top of your trans. It says the ratio on it.

 

not if someone switched out the diff

 

Richmond gear has a really cool calculator on their web sight that works really well. If you know things like tire diameter and your gear ratio, you can plug in different gear ratios and select a desired mph to find out what rpms it will be giving you. I have played with it for my 4.45 gears, and how high I will be revving in 4th at the top end of the strip. Try it.

 

Right, and none of the information I gave applies unless the user is running the factory tire size.

It also wouldn't apply if someone messed with the pulses per mile in the PCM.

I use the following as a base. Yes I know it's for "Honda" transaxles but you can put in any ratios for the gears / fd and it does the calculations all the same.

Honda Transmission Calculator by ZealAutowerks

The screenshot I posed is an 09 SS + HHR LSD 4.05 FD + stock tire size at 70mph.

The difference from 3.82 to 4.05 is minuscule. We're talking < 200 rpm's @ 70 mph.

 

yea its not much at all. when you jump up to the 4.45 it puts me at 3000rpms doing 71mph lol. that short gear life......whew!

 

Yeah but you get there faster...
Gonna run 4.45 trans next year, should pull pretty hard. If I need to do interstate I will just drive my Dakota.

 

I still drive it all over lol. idc. I just cruise in the middle lane. people get pissed they can go around. my TBSS doesn't get good enough gas to drive like that lol.