nicksfoursix

I'm planning a gear set change down the road on my 2005 GT Auto. I plan to keep the vehicle relatively close to stock and my modifications at this time could include a CAI w/tune, mufflers and possibly some appearance mods. I do not foresee a supercharger in the future.
The devil in me tells me to pull the trigger on the 4.10s, but many people who have the 4.10s have manual transmissions and some complain that 1st gear and some of 2nd gear are useless on hard accels from stops as well as high engine RPM operation at higher expressway speeds. I am apprehensive with these types of comments and on top of this, the fact that my vehicle is not a manual, but an automatic transmission equipped vehicle.
The angel on my other shoulder says the 3.73s may be the wiser choice, but I don't want to pull the trigger on this mod (ratio) if the difference is not that noticeable.
I'd like to hear comments and opinions from owners of automatic GTs who have done both the 3.73 and/or the 4.10 gear change(s) and what you like most or more importantly what you may NOT like about your gear change.

avengence

I have always heard the rule of thumb is 3.73s in autos and 4.10 in manuals max for daily driving.

I have 4.10s in my manual and I love it, its just right. Good thing about higher RPMs on the freeway is it keeps me from speeding. First gear on mine is fairly short around town but oh man it is such a big diff going from 3.55s to 4.10s. I guess me going from 3.55s to 4.10s is like you going from 3.31s to 3.73s.

Synyster06Gates

Other way around. For DD'ers most people like 4.10's in their auto and 3.73's in their standards.

stealth_GT

If you want no BS ferocious acceleration in the auto, get the 4.10s ( getting mine on Monday!) From everyone I have talked to, they all love the gears and should have came as an option on the car. I'd just be very leary of stomping on the gas in close traffic or low speed lane changes, from what I have seen.. the 4.10 autos are beasts!

jahudso2

He was correct saying 4.10s for manual and 3.73s for autos due to the fifth gear ratio being taller in the manual. I went from 3.31s to 3.73s in my manual gt and i did feel a difference. Sometimes I do wish I went with 4.10s, but then I get on the highway and I am glad I only went with 3.73s and not 3.90s or 4.10s. If you drive highway speeds (70+mph) for longer than an hour, I would get 3.73s. If you only drive around town, and always take another car on long trips, I would get 4.10s, but that is just my opinion.

blk281gt

I prefer the 3.73's . Your rpm @ 80 mph will be about 2750 with the stock tire and wheel combo. Leave it in 3rd and bring the car to that rpm to get an idea of the sound. If you plan on doing any major power adding, you will be out of first gear instantly with the
410's. My car went 11.89 @ 114 mph on the spray with 3.73's in it.

Mustangs4U

I too am considering doing a gear change as well. I got a quote from the local mustang shop here and they said about 650 and they guarantee no wine or they will fix it. I still can't make up my mine whether to go 3.73s or 4.10s. I do a little highway to work but mainly around town.

Derf00

Keep in mind the 5 spd AUTO tranny in the S197 stangs has a shorter gear than the 5 spd MANUAL tranny in the S197 stangs. Ford did this to keep the 0-60 mph times and quarter mile times as similar as possible and to make up for the added drive train loss.

I think 4.10 may be a bit too much for DD in this case.

5-Speed Manual Transmission
3.750:1 first gear ratio
2.190:1 second gear ratio
1.410:1 third gear ratio
1.000:1 fourth gear ratio
0.720:1 fifth gear ratio
3.150:1 reverse gear ratio

5-Speed Automatic Transmission
3.250:1 first gear ratio
2.440:1 second gear ratio
1.550:1 third gear ratio
1.000:1 fourth gear ratio
0.750:1 fifth gear ratio
3.070:1 reverse gear ratio
5R55S

Orion_240

just be sure to get Motive gears and the lowest priced deal on the install! I'm sure they'll do a great job and you'll have no noise issues, like so many others have!

drbobvs

3.73 for the auto is the perfect street gear IMO. If you're really a 1/4 mile guy then go for the 4.10's but they's get pretty annoying on the hwy. I personally know of 2 people who switched to 3.73 from 4.10 in their '05+ auto's for this reason.