Best gear-tire combo for MPG (1 Viewer)

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Jun 30, 2005
Mayview, MO
I plan to drive the crap out of my 40 when I get her done. 99% street, 1% trail. I have overhauled the 2F and picked up a H55 and split case. Want to go with 33x10.5's on stockers with 4" lift. My question is - will my road worthyness improve with 3.70's instead of the 4.10's?? What is the best (most efficient) cruise RPM for a 2F? What do ya think?? Just want to get the best MPG that I can.
skinny and tall highway tires

nothing too much bigger than stock. adds too much weight

keeping as low to the ground within moderation is better also. keeps wind resistants down and from getting trapped under your vehicle and slowing it down..although its not like the fj40 is aerodinamic in the first place. haha

nice drivetrain combo. im running the same thing
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with 33's and 4.11's, it will give you an "overdrive" on the highway. I can't remember the exact #'s at the moment..... I'm sure someone will chime in with them.

Currently with 36's and 4.11's, my milage sucks......:eek:

i daily drive 82 fj40 with 33x10.5 and 3.70 gears. this combo is perfect on the road. i can run 75 all day long. with the 5 speed i would keep your 4.10's. as far as your milage it is not going to be great with any combo. good luck
Would the 3.70's with the 5 speed drop the revs too low for hwy driving and keep the motor below its powerband? I assumed that since these motors run like a tractor, I would be better off with the higher gears. ????????????????
What is the best (most efficient) cruise RPM for a 2F?
The BSFC curve bottoms out at 1800-2000RPM.

Just want to get the best MPG that I can.
Install a diesel. Drive a little car. drive a little diesel car....
Keep the 4.11's

You'd probly never use 5th. I went to 3.70's last year, and even with a 350, it dosen't seem as peppy as it used to be. 65-68 mph is around 2500 ( rough guesstimate ), anything higher is haulin ass in a 40. Gas milage MIGHT be a little better, but that big 'ol flat windshield is a mileage killer at higher speed. YMMV, Al
Hi All:

X2 what "Eddy" wrote! ;p

Seriously, the 40 Series is such an old design (1950s technology) that it is hard to get good fuel mileage with one. The BJ42 with H55F and stock-size tires probably nets the best mileage.



I think you're going to get 10mpg like everyone else. :crybaby:
33's and 4.10's will be great. Unless you just want to spend the money then I would stick with the stock gearing. Mileage will suck anyway you go. I ran 33x10.5's for a long time before I moved up to 35's and had plenty of power.

Really you can get 15-17 mpg, but don't expect any magic beyond that.

Running 33x1050's and stock 3.73 gears I regularly squeeze out 17 mpg on highway runs, usually at ~65mph. Typically it's 11-12 mpg for stop and go driving around town.
Thanks for all of the input. I think I'll stick with the 410's for now. The 370's are in a parts truck that I have, so I guess I could change then on down the road if I decide to. If I can get 15+mpg I would be super happy. I'll let you know what I get. Thanks all!!!!!!!!!!

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