Sumo Transfer Case Gears

[JOSHD]

Talk to me about transfer case gears. I currently have already done lockers and 4.88 gears. I plan to get the 3.3:1 low range set but do I want the 10% underdrive or overdrive Hi range gears? This is not my daily driver but does see highways to get to the the trails around Colorado. Lots of mountain passes where it is still sluggish even after the 4.88s. I run a 35-ish tire. Thanks for your input.

 

[VPP]

Talk to me about transfer case gears. I currently have already done lockers and 4.88 gears. I plan to get the 3.3:1 low range set but do I want the 10% underdrive or overdrive Hi range gears? This is not my daily driver but does see highways to get to the the trails around Colorado. Lots of mountain passes where it is still sluggish even after the 4.88s. I run a 35-ish tire. Thanks for your input.

Altitude robs power, plan and simple. Even with the 10% underdrive you'll mostly still be shifting down to lower gears at times. Underdrive would result in slower speed when needing to shift down where the overdrive may give you the gearing you're looking for. They are gearing web sites you might want to do some calculating to determine which way to go. Free MPG Calculator with Gear Ratio Correction - https://www.gearheadprovingground.com/mpg.html

 

[x8o8drifter]

4.88s + 35s is almost exactly equal to the stock setup. (assuming you had the 4.3s stock)
99.5% of the stock ratio. So that "sluggishness" you feel is entirely from the weight you probably added and altitude.
A underdrive according to the cruiserteq page says its like going from a 4.3 to a 4.7 FD on the stock size tires.

If I did the math right. 2000rpm in top gear with the 4.88s and 35s and the stock Hi transfer gets you to 65.5mph?
With the underdrive it drops it to 59mph?
The overdrive ups it to 76mph?

 

[OEMGUY0720]

Did a 2000 LC with the 4-speed transmission just the high range Sumo gears, it has 33s tires front and rear steel bumper, rock sliders, long range tank, roof top tent (obviously heaver than stock) - had 12mpg on an average Las Vegas to Southern California and back; now averaging 14.5mpg with lesser gear-hunting.
For low range, this video is the best way to demonstrate it.

 

[frawstme]

if you do a 10% underdrive with 4.88 gearing, its effectively 5.28 gearing. I was originally looking to do the same thing.

10% overdrive would make your gearing ~4.36 which is basically stock. I feel like you are going to be very dissatisfied if you do that since its effectively returning your lc to stock gearing.

at the same time 10% underdrive on 35" would have you around 2650 rpm at 70mph. I think thats tolerable but only if you aren't daily driving it on the highway for long periods of time. 50mph and less would feel significantly less sluggish.

im still on 33" tires so ive only done the 10% underdrive but still looking to do 4.88 gears once these tires are cooked. I don't think its a bad idea since I rarely go on the highway but it is driver dependant