gear choice

[herm0016]

finally getting the 72 Wagoneer done, its been sitting for a few years.

we have difs out of a 76 bronco and are going to build a 2 link system like the bronco for the front suspension. high pinion 44 for the front and a 9in for the rear. they currently have 3.23 LSD gears.

engine is be a 5.3L/6l80/mp whatever transfer case that bolts up. I currently have 33 in tires on it, but plan to go larger in the future.

with the spread in the 6 speed the 3.23 gears are not too bad.
will it work to start out? i figure ill go ahead and put lockers in it eventually.

low is 2.71 on the tcase.

grimmjeeper.com is a good calculator.

looks like with 33's i would be turning about 1500 rpm in 6th at 70 mph.

in low range in first at idle its about 2 mph and at 3000 its about 8 mph.

 

[Bartman39]

herm0016... 1500 rpm at 70 mph will be a bit of a strain on the 5.3 dont ya think...? No torque in that range for sure but the fuel mileage should be pretty good (possibly or not)...?

If it were mine I would lower the ratio's to about a 3.70 or even a tad lower like in the 3.90 area...? This would give you a 2000-2100 rpm band to work with which should keep the torque up on the engine and allow it to get better fuel mileage possibly...?

If you go with larger tires later the it wont hurt it much but with that current setup you would almost be at an idle at 70 mph...

 

[skyking]

1500 would be pushing a straight 6 diesel hard, Bartman is right. your 5.3 would be hurting.

 

[herm0016]

yea... sigh... better to do it right. looks like ill be shelling out for new carriers/gears/etc. full rebuilds of the difs. looks like 4.88s would be the best at about 2k rpm 70 mph in 6th with 40 in tires. 4.10 would put me at 1600 with 40's.

the 9in has a 4.86 gear not a 4.88. 4.11 instead of a 4.10 less than 2% is the rule right?