Originally Posted By: exranger06
I love low gears. I checked the gear ratio on my Ranger before I bought it, and was pleased to see it had 4.10s. My Bronco currently has 3.55s (as almost all Broncos had 3.55s) and they are terrible. I don't know what Ford was thinking when they decided on this ratio. Bad for around town acceleration AND bad on the highway. Overdrive is almost useless except on the flattest highway. Go up the slightest incline and it downshifts to 3rd. I'm regearing it to 4.10s as soon as I get the time and money.
A lot of vehicles are geared much taller than necessary ONLY for the EPA test cycle.
It's an argument that always comes up on facebook groups for Jeeps, for one. The 4.0L high output engine makes it's peak torque, and hits its volemetric efficiency > 2000 RPM. Gear it on the highway so it's running at 2300 RPM and it's going to get better fuel economy than running along at 1000 RPM with factory 3.07 gears. The 4.0L that could pull those gears and still get good fuel economy was the Renix - "non high output" 4.0L. They also got better mileage in stock form.
A lot of people seem to think it's linear with fuel economy and that, in all situations, higher RPMs are bad. Ideally, with my current 32'' tires, I'd gear my Jeep at 4.56 gears and cruise at 65 at ~2700 RPM. It would have no problem doing that all day, every day and very likely get better fuel economy than stock.
My parents had 3 TJ Wranglers with the 4.0L engine and 5 speed manual. One with 3.07 gears , one with 3.73 gears and one with 4.10 gears. The one with 4.10 gears always had the best mileage. Except on the EPA test cycle.
A modern gas engine - and that includes ol' bubba's swapped in carbureted 350 (because he can't figure out that got-dang high technology fuel injection) , a ford 300I6 ... would have no problem running 2500, 3000 all day long on the highway.
