ok guys heres my situation...

1999 4x4 f150 and 3.55 gears
the mods:
edge programer
cat back exhaust
cut factory cats out and replaced with 2 high flows

now i have just installed 285/70/17 bf all terrains... the truck came stock with 245/75/16

i tow an approx 2000 lb boat quite often in the summer time... the truck is my daily driver to and from work etc... its what you would call a city 4x4 i don't ever take it muddin and never plan on it...

so after all that information my question is would it be worth my time and money to install 4.10 gears in the truck ??? what would be the biggest gain i would see??? any change in fuel milelage??

your thoughts and advice is greatly appreciated

thanks

Jeff

 

definately go with 410's if you are going to do a swap.. Dont even consider 373's. Your tranny will thank you. I went to 410's on my 05 , with 4.6, scab, it needs all the help it can get. with 275/70/70 rubber i'm turning a little over 2k at 65. I have seen NO measurable effect on fuel mileage. Keep in mind that this will ease the load of the engine while pulling the boat. But if you do a lot of highway driving, you might see a lil change. But the taller tires will most likely offset the gearing....so your not really gaining a whole lot. rossford 05 scab, 411 yukons, 4.6 w/edge, 9.75. got to love it.

 

I have the stock 3.55 gears as well with similiar mods, I also run a 35" Tire year round. I tow quite often usually 4000 lbs or so. Its a bit slugish on the long up hills but all in all I have no complaints with the ratio. It would be nice to have the lower gears but can't justify the cost. 2000 lbs isn't a lot to tow in my opinion.

 

this is a great thread i am also considering a 4.10 or 4.11 gear change on my 04 4.6L.
i have the same situation i drive this 4x4 daily and tow a trailer some times 3 days a week.
i have been watching the rpm's lately as i drive and my cruise rpm in overdrive is right around 1700 give or take.
i figure changing from stock to 4.10 will add just under 400 rpm to that and anything under 2200 rpm for a cruise speed should not effect mileage much if any.

according to the info i found a cruise rpm of 2000 to 2300 is optimum for fuel economy

2300 to 2600 is an acceptable rpm for a little more performance and slight loss of fuel economy

for the ultimate power hungry driver gear to achieve 2700 to 3000 rpm at cruise if mileage is of little concern but passing power is on the plate.

 

i too have a few questions:

i am about to put 35" tires on my 06screw 4x4 5.4 with stock 3.73s

from what i have read during thread searching is that my truck will most likely be a dog with those big tires, and that i may have to re-gear with 4.56s.

1. stupid question - on a 4x4 do i have to upgrade both diffs or just the rearend?

2. how do i find gears for the front diff, is it the same as the 9.75" gears in the back?

3. im guessing that this proposed gear change will not only give my truck its "pep" back but will also help restore some of the lost fuel economy since the engine wont be working so hard? not all of course, but some?

thanks!

 

1. Both, or you can't use 4wd.

2. 8.8" reverse cut for the front.

3. Yes, but you should also get a programmer and tunes.

 

how can you identify what front end you have on your rig ?.
i would like to regear my 04 4.6L 4x4

 

http://www.diffwizard.com/

 

All recent 4wd F-150's take 8.8 reverse cut in the front.

 

OK so the rear is a 8.8" LS 31 spline and the front is a reverse cut 8.8" 28 spline.

does that sound about right ?
04 XL 4x4 4.6L

 

next question is with 32" tires should i just step up to the 4.10 gear ratio or go all out for the 4.30 ratio.
my thought were the 4.10 should wake it up just enough !

 

oh ! lots of questions here, i never did a gear change in a rear yet but i did take some apart and did install lockers.
anywho do i want to buy the basic ring and pinion install kits
or the complete ring and pinion install kits for 2x the price ?
or motive gear even offers a super ring and pinion installation kit.
then you have the state of the art smart sleeve ring and pinion installation kit.

this is complicated, just to many freakin choices.

and i do have a dial indicator and magnetic base already.

 

You can't get 4.30's for the front.