If I was to order a set of 3.55 gears from Ford Racing would I be able to have a Ford dealership service dept. install the kit? Would the kit wreck the powertrain warranty? Cost of doing the work? Thanks.

 

It all depends on the dealership, though i doubt they would turn away the work.

As far as the warranty goes, that's definitely something i would discuss up front. Chances are they would warranty the work for 12mo/12k mi, but could possibly void the rest of the powertrain.
As stated many, many times on this and other forums, they would have to prove that the gears caused the warrantied part to fail, but you might have more of a leg to stand on if the dealership installed it and caused the issue.

Price wise, you're probably looking around $300-$400

 

Thanks, heck I might go to a dealership and let a service rep "talk me into it" like it was his idea and then get him to explain how they'd reflash the pcm to take into account shift points and ratios and stuff. Document all of that if it goes down like that. But this is just getting a feel for stuff I might do down the road since the options of adding power and performance for this car are many. I actually aint even complaining about the 3.15s installed yet. They seem to be dialed in pretty decently for the car. But I do wish Ford would have made 3.31 gearing ratio the standard for GT automatics. I saw a new V6 Mustang on the lot today with 3.31s installed as part of a performance pkg upgrade that I wasnt aware existed for 2013.

 

would you consider 3.73s or 4.10s? you wont see much difference from stock to 3.55s

 

Excellent point. My vote would be for 3.73's. With an automatic you have a 4.17 first gear ratio. 4th is 1.14 with 5th & 6th OD gears. These cars seem to be right at home with 3.73's IMHO. I disagree that you will not see that much of a change from 3.15 to 3.55, but that is just my opinion. That is a pretty big bump. Still I think you will be very suprised & impressed with 3.73's.

 

From what I hear about automatics you either want to stay with 3.15's or go to 4.10's, anything in the middle isn't worth it. That's just what I hear on the forums, I drive a straight shift with 3.73's so I haven't actually experienced the ride.

 

Thanks for all the info then. So the ford performance bump to 3.31s is probably totally worthless as an upgrade from stock in the auto cars I take it? Will consider 3.73s strongly if I do a gear swap. Thanks.

 

So going off your original post, wasn't much info on the basics of your car, so after provided info, i would def bump to 4.10's in an auto
Agreed that going from 3.15 to 3.55 you will only notice slight improvement and maybe a little more with the 3.73's

You've got an auto, only 2 pedals to worry about (stop and MASH), so those 4.10's will def be a "kick in the pants" upgrade.

 

How are 4.10s on the highway and do they hurt top speeds? If it's just for the neck jerk factor I already have three herniated discs in my neck from rough livin' so 4.10s are gonna have to cut it for all sport type driving conditions for me to consider them. I do like the 4.10s in my Ranger FX4 however!

 

I wouldn't go with 4.10's. It would make 1st gear totally useless. Also I'm not so sure a dealer can compensate the PCM for the gears since it wasn't an option in the autos in the first place. You might need a custom tune. Also 4.10's will have a negative impact on gas mileage if that's a concern.