after i installed i i heard 3" is a little harder on the ball joints, but thats a far cry from replacing them every few months. You know that for a fact? Or just had to get your opinion in?

 

The most beneficial part of regearing is it takes the stress off the tranny.......

 

I have the stock XLT gears (3.56?) and can't remember but they are smaller then FX4's. Tire's are 95lbs/ea Toyo 37x13.5-17 (I believe Toyo list the actual width closer to 14"). I avg 14.6 with 50/50 hwy/street. I can get 18mpg long hwy. You are getting worse mpg with bigger gears and smaller tires. Yes gears return low end power on the street (just as a electric fan mod does) but it increases your rpm's, so you trade hwy mpg for city.

Mods: Custom tuned edge, headers, CAI, forged aluminum rims, separate/dual exhaust header back and 7" lift.

 

in town my mileage ranges from 11-13MPG and on the highway with cruise set at 70mph i can get around 15-16 MPG. Mileage wasnt my main concern for regearing i was more concerned about transmission problems down the road. I also tow a fishing boat so the gears have helped considerably. One of the best mods i have done next to the programmer.

 

I am as guilty as everyone else when it comes to modifying my truck, but here's a little food for thought:

If you drive 20k miles a year, and get let's say 14 mpg. That's 1429 gallons of gas a year. The current national gas price average is $3.70 a gallon. $3.70 x 1429 gallons = $5287.30 a year in fuel costs.

So, same setup, but we add a tuner or gears or whatever, and now you're getting 15mpg. So, let's run the numbers, now you use 1333 gallons a year, that's $4932 a year in fuel costs.

That's $355 difference. You probably paid that much for the tuner, or if you do gears you're looking at over a grand usually.

The true difference with tuners and gears, etc, is going to be torque, acceleration, but not MPG. If there was a miracle cure for adding MPG's we'd all know what it was, they'd sell it at every auto parts store, and the vehicle would come with it as an option from the factory.

Just something to think about…

 

I would not go so low in gearing. Look at it this way. Your stock tires on your f150 were probably 275/65-18 or 275/55-20. The 18's being 32.1 inches, the 20's being 31.9 inches. Either way, you have a 32 inch tire stock. Increasing to a 35 inch tire, you are only increasing your tire size 9.375%. So to keep stock performance, go 9.375% deeper in gearing. that would be 3.88. Obviously they don't make 3.88, so you would go up to 4.11, which would put you about 6% deeper than what you have from the factory. I know this is a little simplified because I am not taking into account the increase in tire width, but it has worked great for me in the past, so I'm sticking with it.

 

Thats something good to think about!

 

The problem is your assumption is looking at tire diameter when what really matters is tire circumference and weight. Revolutions per mile drops significantly when going up in tire sizes, especially a 32 to a 35. A 4.56 ratio with 35s will turns you 6% quicker than factory setup. A 4.10 setup will put you right near factory specs, but the huge increase in tire weight and rolling mass make the 4.56 a good option if you ever drive hills.

 

I have a 4x4 screw with 5.4 on 35's and 3:55's and can squeeze 15mpgs on the highway and usually get around 13mpgs. That's with a 2.5" Level btw.

 

I have been looking into regearing for sometime now as I am running 37x13.50x20's on 3.55's. I did add a programmer wich only adjust up to 35" tires and a K&N airfilter. As of yesterday I am getting 14mpg 50% city/hwy. Granted my rpm on the hwy at 65 are turning 1500. I am please with the mileage, but when i hook up to the 24' boat it kills it. Also, not sure if anyone has hear this. I spoke with a local axle shop and was told that the most you can go with the 3.55 is 3.79. Anyone know if this is true or false?

 

If you have 37's, you need at least 4.56's if not 4.88's.

 

DONT GO TO THAT SHOP!!! they are ignorant! im running 4.88s and i had 3.55 gears. what gear ratio you had previously doesnt matter becuase its getting replaced. hell i think they make 5.13's for the 9.75 axle.