Gears - Ford Forums

jasonw1983 · 10-03-2008, 18:45

I have a 2001 F250 V10 with a 6" lift and 37's and want to put gears in it, but not sure of whats going to be the best. I dont really tow a lot... a 24' boat once in a while but not very far. Thanks

847alexc · 10-05-2008, 09:48

Wow!

I think some of the super duty dulies came stock with like 5.38(?) gears. You probably want something like that for tires that size. Though with the torque comming out of that v-10, that might be excessive. Are you looking for more torque?

**360ci** · 10-06-2008, 17:14

The 4.88 and 5.38 gear sets only came in the F450 and F550 series trucks which have higher GVWR and need the lower gears to move the greater mass. F250 came with 3.73 axle ratio. To check your axle ratio look in the glovebox for a sticker - the ratio should be listed on there. Check out Yukon Gear & Axle and you'll be able to find axle ratios. Best thing is to contact them, or another local place that installs gears to know what you'll be able to put in your axles. I'm guessing a 4.30 or 4.56 ratio may be the highest you can go in the F250. If you have 4.1's already you won't notice much gain with a 4.56 setup, but it'll still help.

jasonw1983 · 10-08-2008, 18:26

I'm looking for a little better gas mileage... But dont want to give up all my torque and power.

847alexc · 10-14-2008, 20:31

really!?

Then you want to go the other way with the ratios. All the advice we have been giving you is for what most other people want, especially when it comes to larger tires.

Simply by putting those larger tires on you have effectively lowered your final drive ratio. Meaning (lets say for argument sake that you started with 4.10 gears) that you have effectively brought your final drive to be more like a 3.54 or 3.73. This over simplifies of course.

If your gas mileage numbers aren't looking any better I would remind you that after such a dramatic tire size change (or gear ratio change) you need to recalibrate your vehicle speed sensors (the PCM actually). The factory ford shop can do this but you can also buy a programmer. With out this your speedo, electronic auto trans, and odometer will not be right. This could potentially damage your trans also! your mileage numbers will go up as the larger tires cover more road per rpm.

Start there if you haven't already. Seriously! after that, consider what your engine stock torque numbers are, then assess how low a ratio it can handle. you don't want to bog your motor down