XLT4x4/3kgt

i know the bigger the tires you get that you want to re-gear. If i get 35's should i re-gear? I know plenty of people that have put 35's on and they never re-geared anything. i didn't know if they didn't re-gear because it doesn't make much of a difference, or if because it cost to much money. Does anyone have an answer or an opinion?

NICKHEAD

My .02 cents would say.. GEAR IT.. unless its the grocery getter.. mine has 35's on it and I first geared to 4.11 then to 4.56 for fun just to see.. and the 4.56 is better when i have the need for bottom end power, towing and yanking chevy's.. yes you will lose some top end, but when do you need to do in excess of 95mph??.. I went with an Auburn 4.56 posi..

XLT4x4/3kgt

how much of a gas mileage decrease did you notice after re-gearing?

also on a 00' 150 with a 9 1/4 rear end does anyone know what gears are in them? are they 4.10's or 3.77's?

wde3477

Suggest for the difference in tire sizes, you will want to re-gear. Keep in mind with 4WD, will need to do both axles - not cheap.

There should be a tag on your axle, or in the driver-side door jamb that has the ratio information. If there's only a 2-digit code listed, there are numerous resources on the Web to decode it.

Once you know your current axle ratio, multiply that by the ratio of the new tire diameter divided by the old tire diameter. This will give you a ballpark number to strive for, with the likelihood of needing to round up or down to get to an available ratio offering. Suggest that most members will advocate rounding up to the next higher ratio.

wxmcpo

I went with Yukon 4.56's when I re-geared. Regained all the lost power and no more gear searching when I'm climbing those hills.

rndgen

I went with the 4.10 gears to match my 35" tires. I calculated that this tire diameter and gear combination resulted in a 6% underdrive compared to the factory tires and gears. The result is a little extra low end without sacrificing gas mileage.

I towed my friends boat this summer and was able to pull the it up the hills without dropping speed, although it did kick down a gear on some of the steeper inclines.

I'm happy with my selection. If your looking for crazy low end grunt then go with the taller 4.56 gears, but you'll trade off gas mileage and top cruising speed.

MHC-F150

Here are the most common gear setups for the 97+ F150s.

19 — 3.55 non-limited slip
17 — 3.31 non-limited slip
H9 — 3.55 limited slip
B6 — 3.73 limited slip

http://www.ford-trucks.com/article/i...de_Chart_.html

Here are some good resources to find the best gears to choose for your setup.

http://www.novak-adapt.com/knowledge/gearing.htm

http://www.4lo.com/calc/geartable.htm


EDIT: Forgot to add my suggestion, which would be for the 4.56 gears and yes do it. As you'll notice in the 4lo link provided, with the 35"s & 3.73s you'd be very low on power.

ctfox

put a mark on your driveshaft and put a mark on the closest none moving part... jack up the back end, spin the tires (together) one rotation and count how many times the mark on your driveshaft went completely around....example mine is a 3:73 and it went around 3 3/4 times.....its not perfect but gives u a pretty good idea.

buzzin 1/2 dozen

OP,
I thought all 3.5 Ecoboost trucks have the 9.75" rear axle. I see they quoted you for an 8.8. Is that correct?

M0RRIS