RPM question

[MadTripper]

This might help when searching for options.


http://www.grimmjeeper.com/gears.html

[Steven]

That's the calculator I've been playing with. I'm going to be running 38 tsls and with 5.13 gears it will be about 2700 rpm at 60mph. I probably won't see 60 very often, mainly just when I drive 10 miles to the trail.

[MadTripper]

I knew I had this buried somewhere but couldn't find it immediately. A friend from another site created it and I hope he is fine with me sharing it. Might help some people out down the line. See attachment.

Thanks Randy!

[limited slip]

my daily has her original 4.1 diff's but has a 5 speed from an mq/mk wagon- the box would have originally had a p40 in front of it, but its 4th gear is the same as the 3 speed's 3rd which is 1:1. at 100kmph/60mph this ute is doing 2300rpm- that's with 285x75r16 tires.

red six, the farm hack, had some 32x11.5r15 on her when i got her, the speedo was spot on +/- 3kmph with them according to the gps, she has a tacho on her the previous owner installed, and is doing 2200 rpm at 80kmph in 3rd. she would likely be pushing 2600 rpm at 100kmph.

if your keeping the stock g/box but running bigger tires and still wanting some drivability on the tarmac then i would suggest the following:
tires of an actual diameter of 33 inches, 4.3 ratio will maintain the same gearing as the original drive line had, 4.6 will give you a touch better low range crawl, but will increase your rpm by around 200rpm.

tires of an actual dia of 35inches, 4.6 will maintain the stock gearing, 4.8 will give you the slightly better crawl- again will increase rpm by around 200 @ 60mph

tires of an actual dia of 37-38 inches would have stock gearing with the 4.8 ratio's, but anything of 5.0-5.25 or so would be much better for drive ability, and give a bit better bottom end torque, really though from my experiences with my g60swb on 35's i would say that 80-90kmph would be the most comfortable cruising speed, and pushing big wandery rubber at 100kmph with the stock steering set up is more than a little hair raising.......

if your planning 38's, go the 5. whatever gearing, that should provide the best all round gear ratio's.....

cheers
kev

[Steven]

I've decided on 5.13 gears, they will give better torque. Most likely will be cruising around 50-55 at most, will never see an interstate. The steering will be a hi steer dana 44 set up.