Ok, mine is not a disco.
Now I just have to save up some money to get it regeared and locked! I'm thinking a eaton electric locker and I'm torn between 4.56 & 4.88 gears. running 33's now plan on 35 - 36's in the future.
yes i am thinking alot about what gears i just ordered 35's aka the street tires and am looking for a set of 38" bias stickies i really want the maxxis cc's or the pit bull rockers and i am going to drag the 38's around on a trailer till i go to wheel or light wheeling run the 35's but since this is still my planned dd i am leaning toward 4.88 but i want 5.13 for off road but then i have to look at what i will be doing with the jeep
so my thoughts are if i run 5.13 my highway rpms on 35's will be about 2500 rpm @ 65 with the ax15 (i looked at a chart that was for 1 to 1 and multiplied by .79 the ax15 od gear ratio) which is not bad but my jeep will suck more fuel and my crawl ratio is going to be 51 to 1 at an off idle speed (1000 rpm)in 4low of 2.2 mph and my normal wheeling speed(aka motor red line) of 5.37 mph in first gear on 38" tires
with 4.88's highway rpm on 35's is 2400 crawl ratio 48.97 to 1 off idle speed 2.31 mph on 38's
so the differences are 100 rpm @ 65 and every thing else is about the same the only thing that i am considering is how much fuel i will waste with the difference in gears if i new the standard air to fuel ratio i can calculate out fuel consumption per hour per rotation and make a rough guess looks like more research
the more research is in
OK edit i found that air to fuel ratio's are about 12.5 to 1 up to 13.3 to 1 for the most power for engines powered by octane pump gas is 87% octane so close enough for me
a 4.0 moves 4 liters of air per 1 rotation of the crank an d a liter of air weighs 1.2 g/L so afr= mass(air)/mass(fuel) then with a AFR of 12.5 i get about 2 grams of fuel used per one rotation of the motor
so at highway speeds between the 2 gear ratios i have a difference of a 100 rpm or 200 grams of fuel per minute or about .3 lbs/hr or .043 gallons per hour difference
from what i calculate it really is not much difference between the 2 a little more fuel will be consumed and i get a little better off road performance with 5.13 over the 4.88 i need a butt dyno on both sets of gears to see if it worth it will i really notice the difference between 4.88 and 5.13 on the trail with 38's i know i will see a difference in fuel consumption, acceleration, speed, and noise level so what do i do i guess i could take the money i don't waste on gas using the 4.88 and put it toward the lo-max 4 to 1 low for the d300