lanesteven4570.

As anybody run the 3.55 gears in a f150 4x4. I'm thinking about doing that in few weeks. Wanted yalls opinion would be going 3.08 to 3.55. My truck has the 4.9 straight 6 it has 31 inch tires on it now, in few months will be puting 4 inch lift kit on 33's truck had the e4od trans, I will be doing 90% of my driving on interstates after May.

Brandon587

Specify you have a 4.9 and 30 inch tires as well as soon to be used mostly on highway😆. Oh and e4od trans.

lanesteven4570.

Ok tks

Chris_1

iTrader: (1)

Most of the 4x4's came stock with 3;55 gears. You should be fine with 33's.
If you were going to 35's you'd want to be looking at 4;10 gears for sure.

lanesteven4570.

Do you have 3.55 in your truck ?

Chris_1

iTrader: (1)

No, 3;08. I have a 3;55 Diff ready to install but haven't bothered yet. 3:08 works ok for me w/ 31-10.50's and a 302 auto.
Thing is it's a bit of common sense thing for your situation.
The ratio is how many times your driveshaft goes around in order to make your rear wheels go all the way around once.
If the motor can go around more times in order to move the truck ahead a certain distance then it won't have to work as hard to pull away from a stop or climb a hill. So a little easier on gas in those situations.
But on the highway the motor will have to spin like crazy to keep you up to speed. So not so good on gas.
By putting on 33" tires you make the motor work harder - putting in 3:55 gears you balance that back out some. 4:10 will make it even easier on the motor but it'll use more gas on the highway.
Generally you're going to get optimum mileage around town OR on the highway, one or the other - not both.

lanesteven4570.

I can't thank you enough for all this info your giving me. I have been told by a friend of mine that has a f350 single tire with 460 big block my year model truck he thinks I should put in 4:10 or 4:56 what is so great about those gear ranges?

Chris_1

iTrader: (1)

Great for 1/4 mile racing or spinning the tires from a stoplight. Not so great for fuel economy on the highway. Unless you have great big monster tires, then you would need lower (higher number) gears.

lanesteven4570.

Biggest I'm going is 33's on tires

Chris_1

iTrader: (1)

3:55 is the most you probably want to go with all that highway driving on the horizon. 3:73 maybe but that's going to cost you in fuel. 4:10 would be like driving with the overdrive off.