05screaminyellow

right now my car has 3.31 gears with a 5 speed on stock 235/55R17 tires

I am wondering if any of you guys have upgraded to 3.73 with the 5 speed stick and 4.0L what rpm are you running at 65/70 mph?

and was it a noticable difference in get up and go?

drfister

Here you go; this thread should help:

https://mustangforums.com/forum/4-6l...-and-mphs.html

I had 3.73s installed with an aluminum driveshaft a few years ago, and they've been some of my favourite mods. I dont really do enough highway driving at consistant speeds to be able to tell you off hand what the rpm's are, but they dont increase by much. I've never experienced 4.10 gears, but those that have them love em too. I know with the 3.73s it just seems like she wants to keep going and going. Definatly a worthwhile mod.
Ideally, get a takeoff 8.8 rear end with the gears of your choice, otherwise stick to frpp brand gears. Im going to go out on a limb and say if you do tear apart the 7.5 rear to change the gears, it would be stupid to not change to some sort of locking differential at the same time.

crazyassracer

hmmm noticeable difference? Yeah I guess, maybe not as much as I was expecting. I agree with drfister, switch to a LSD when you change the gears. The T-lok made a big improvement in launches. The down side was having to upgrade my lower control arms to combat wheel hop; not a big deal though.
In my case changing the gears, differential and LCAs added a little more noise to the drive, but also added some fast.
I run about 2800 RPM at 80mph.

157dB

A swap up to 3.73s will allow you to run a taller tire and still
get 3.55 like performance.
Kinda fill up those wheel wells a little.
The 235s wil not like the 3.73s without a T-Loc installed.
And then there is the nightmare of whine you might have.
Many a story around here of motive gears and improper installs
that result in gear while that cant be gotten rid of and loss of
use of the stang from being in the shop having the gears looked
at.
Others buy good quality gears and take them to a qualified rear
end specialist (not talkin about a left hander with a lift and
a wrench) and never have a problem with noise.

Some FRPPs are Motives in FRPP packaging and sport the
flying "M" stamped into the ring gear. No good.