howarmat

This is the way i look at it

These are the internal gearing numbers for the trannys. Since the auto and manual transmission have different internal gearing, the rpms and such are different in different gears.

Automatic transmission gearing
1st: 3.22 .1
2nd: 2.29 .1
3rd: 1.55 .1
4th: 1.00 .1
5th: 0.71 .1
Rev: 3.07 .1

Manual Transmission gearing
1st: 3.38 :1
2nd: 2.00 :1
3rd: 1.32 :1
4th: 1.00 :1
5th: 0.675 :1
Rev: 3.38 :1

The final drive gear is calculated by using the tranny ratio times the rear end ratio

So in 5th gear you would have
M: 4.10*.675= 2.76
A: 4.10*.71=2.91
A: 3.73*.71=2.64

Ideally a 3.90 gear set in the auto would equal the 4.10s in a manual but they are NOT a FRPP gear so that is one reason most people do not use them.

Notice other gears besides the final gear too......some of those numbers are much different in the auto than the manual. Its really personal preference but usually you are stepping up from 3.31s in the auto and going up to the 3.73s will give you a nice kick in the pants and the RPMs on the highway are not terribly high this way.

Derf00

That gearing in the Auto is also why stock for stock the Auto is comparable to the manual tranny in terms of times (60mph and quarter). The inherent additional parasitic loss is somewhat compenstated by the shorter gearing in some of the gears on the auto.

Nighthawk2008

I have 4.10's in my auto and LOVE em. My car is a daily driver, 50/50 city/highway. I debated between 3.73 and 4.10 for awhile before I made the leap. Glad I made the right choice for me. They really woke the car up and it pulls like a beast now. No regrets here.

LL05GT

I personaly would recommend going with the 4:10 setup. I love the my setup and would do it again if i had to. I only have FRPP 4:10s, SCT tune and SLP's. Last week ran a 13.5, not to good but i credit the gears for what i got.

Norm Peterson

Those are pretty short tires for 4.10's, about like 4.4x with OE size tires and getting very close to the 4.56's people used to run "back in the day". What gear and rpm were you seeing as you went through the traps?


Norm

Mishri

thats one thing I was wondering.. 4th gear is the same in manuals and autos right? and if most people are finishing the quarter still in 4th gear with 4.10s wouldn't it make sense to stick with 4.10s for an auto too?

kolb02

Mishri, yes you finish in 4th gear at about 5500, Just get the 4:10's, For everyday driving and some track use they are perfect. If you can't make up your mind come over and I will let you drive mine on the interstate, and you will love them.

stealth_GT

I don't think it's 1st gear that's all that short but from what I have seen in vids,it's 2nd and 3rd that are super short and are accounted for the ferocious acceleration...could be wrong.

stealth_GT

ditto..it's like that up here too. It sometimes feels like there is no speed limit lol.
fools go 85-100 all the time.

)-:

makes me feel like a granng putting around in the GT...

Whiteflash454

4:10's FTMFW TRUST ME...its amazing!!!