3.31 Gears to 3.73?

Thats the mod I did a few months back. Plus swapping the drive shaft for an aluminum one. As far as top end goes, the theoretical reduction is in 4th gear there there is about a 17.5 MPH reduction at 6250 RPM. From 153 to 135 MPH. If you could get to 153 with 3.31s. There is way more going on than just RPM vs speed. Air drag for example. If you include 5th gear, then its a moot point because you don't have enough horsepower to top out overdrive.

My highway MPH went down 8 to 10% with the 3.73s. City driving gets about the same and maybe a tad better depending on how you drive it. You can run the RPMs a bit lower with the 3.73s is why. On level streets, you can roll 4th down to 25 MPH and 5th down to 35.

I am shifting sooner and more often in town trying to keep the revs low if I want to save gas.

Starting from a stop is much easier on the engine and clutch. Driving slow in parking lots (including the traffic jam kind) is using less clutch.

The car feels like its rolling a lot easier. Its a better gear than the 3.31s were over all.

Jumping on the freeway the car feels much different than stock. It accelerates harder. Where as the 3.31 would last to over 70, the 3.73s need to be out of second at 65 and into 3rd. Which is fine. 3rd is an amazing passing gear now. 5th can pull grades at lower speeds now where before I needed to down shift.

Its a great mod. Use Ford gears for best results if you can get them. I had to wait a couple months to get my set. Seems as though Ford is using them all for something and is hanging on to them.

My car has 3.55s...and I was wondering it I should go 3.73, or up to 4.10?

I don't go to the strip at all, but like to jump on the gas around town from time to time. Would 4.10s be to extreme?

Definatey get a shop to do it - it's not for the novice! Use FRPP gears as people on here have had gear whine with the Motive brand. 3.55 > 3.73 would be a waste imo.........the spread between the 2 ratios just isn't far enuf to really make a huge difference. Generally speaking the 3.31 ratio usually goes to the 3.73 - 4.10s ansd the 3.55s go2 the 4.10. The 1st gear in a stick car would be very low, but the acceleration would be amazing. It also depends how you drive (hwy or in town driving or a 50-50 mix etc). Most likey sum1 else will chime in that has more experiences with their own gear swaps. Me personally, I have the 3.55s and will go2 the 4.10 ratio. As I've said before............. don't fear the gear!!!

Sparty92 said:

My car has 3.55s...and I was wondering it I should go 3.73, or up to 4.10?

I don't go to the strip at all, but like to jump on the gas around town from time to time. Would 4.10s be to extreme?

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3.73 / 3.55 = 1.05

Its only a 5% change. If my car had some with 3.55s I would not have put in the 3.73s. But since I was sporting for the gear change, I went for the 12.6% jump instead of the 7%.

I went from 3.31 to 4.10 and love it!! I have an auto trans though. Its awesome. Car is in the power band now. Defiantly get a good shop to do the install. Nothing worse than a crap gear install......whining an groaning... dont go there. Like the others said, ford racing gears only!!

patrick

IMO I would go with either 3.93's or 4.10's. 3.93's arent as steep if thats what your worried about but they will improve acceleration and power through each gear. Personally for this year model I would go with 4.10's and I actually just ordered them. I do know people with 3.93s and they do like them and you can tell a difference performance wise.

Also I agree definately have a shop install it. Too many errors can occur, such as if it is off 1/1000 of an inch which is less than a sheet of paper it can mess up. Also if not done correctly will run right for a while but will eventually start knocking. If your car has over 50,000 miles or if you want eaxtra sexuroty go ahead and get the bearing kit. Just better for the car.

think about everything you want done to the rear end or/and needs to be done and get it all done at the same time. Even if it means saving up for a few months. Saves money and time.

1KillerGT2010 said:

Hey i'm just curious has anyone with 3.31 gears changed their rear end to 3.73? I want to get more acceleration and i figure thats my best option, just wondering if it is difficult to replace by myself or should i get a shop to do it for me? If anyone has replaced their gears to 3.73 what is your top end at now? Thanks hope to hear some feedback!!!

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Yes the car will accelerate much better. No it's not a mod i recommend doing your self.

Sparty92 said:

My car has 3.55s...and I was wondering it I should go 3.73, or up to 4.10?

I don't go to the strip at all, but like to jump on the gas around town from time to time. Would 4.10s be to extreme?

Click to expand...

If you don't go to the track then I wouldn't advise changing the gears at all unless you like to street race (which you shouldn't do), then 4.10 and a sticky tire will be your best bet.

Many of us who've done gear swaps on 2005+ GT's went with 4.10's with no regrets. My '07 GT Automatic has 4.10's and it's a daily driver. I almost went with 4.30's (which I had in my '03 Mach 1), but the math didn't pencil out for my needs at the dragstrip and highway, so 4.10's it is. Best bang-for-the-buck after a supercharger, IMO.