S197 Gear question(s)

**SV1000s** · 04-02-2008, 10:16 PM

I am putting gears in my automatic 06 GT. I am torn between 3.90 and 4.10 gears. I don't want this to get into a discussion about what manufacturer makes better gears and all that. The car is a daily driver AUTO with the stock 3.31 gears. I do not "fear the gear" however since it's a daily driver I don't want the gas mileage to suffer "too" badly but I definitely want more performance and 3.73 gears won't cut it!

What would you rather have in your S197 auto daily driver.... 3.90 or 4.10's and why?????????

**White5.0** · 04-02-2008, 10:20 PM

its an auto....go 4.10's

**fastfox91** · 04-02-2008, 10:41 PM

hell theres really not that much difference there, i would go with the 4:10s

**Troll** · 04-02-2008, 11:12 PM

those gears don't seem too far apart, but when comparing to 3.31 there's about a 6% difference depending on how you want to calculate it. I would divide the difference in ratio back into the 3.31 because that's what you're starting with. So here goes, 3.90-3.31= .59 / 3.31 = 17.8% increase in ratio AND 4.10-3.31= .79 / 3.31 = 23.9%.

From my personal experience in two 5-speed 2V N/A cars (one with 3.73 and one with 4.10) stock gears similar at 3.27... your butt don't notice much difference with anything less than 25%. With the 3.27, the 3.73 calculates about 15% and the 4.10 about 25%. After I sold the 4.10 car, it was about 9 months before I drove any Mustangs. When I drove the 3.73 car, it felt stock to me. ???

As far as gas mileage goes, that really depends more on your foot than cruising at 2,300 or 2,500 on the highway. Don't those have 5-speed autos? what's the o/d ratio in that anyway?

I don't know what all you got done to that car, but if you do intake/tune/underdrive pulleys, you should be able to get back any mileage you would lose.

these are just my opinions, of course.

Just remember... no matter what you do, make 4 posts about it and then don't tell us what you did.

**92306gt** · 04-02-2008, 11:18 PM

4.10s FTW!!!

**Viper_ed** · 04-03-2008, 12:21 AM

I say just put another 250 RWHP in it and it will be a GREAT car. At least I know mine would be with that mod. Honestly, the 4:10's should be fine. You're really not going to see that big a difference in rpm's over the range of gears you're looking at. I know that if cam303 had a 5:xx gear laying around, they would be in his instead of the 4:56's.

**cam303** · 04-03-2008, 12:22 AM

I would do the 4.10's.....with 4.56's i am at about 2500 to 2600 rpm at 65mph with a 5 speed. I think i am going to go with 4.30's though because the ground down pin in the rear is making me nervous. the gears made a huge difference though.

**Viper_ed** · 04-03-2008, 12:23 AM

Hey Chris, I want a ride in it before you switch them out.

**cam303** · 04-03-2008, 12:30 AM

No problem but we better make it soon.

**SV1000s** · 04-03-2008, 08:14 AM

Troll - yeah the car is a 5spd auto. Thanks for the calculations as they were very helpful

The car has an axle back exhaust and intake only.....it's getting gears, tuner, & springs.

I'm leaning towards the 4.10's ....anyone have any 4.10's sitting around they would like to part with before I purchase a new set from our friends at Summit????

Thanks for the input everyone