Outer Limits 4x4 Board

Looking at reducing the gearing of my sierra, and the bible doesn't really answer what i'm talking about

just wondering the advantages/disadvantages of the different methods of doing it, Changing gears in the gearbox, transfer case, or diffs.

The car is running 31" tyres and rockcrawling is nearly impossible. Gear 5 also sits at 3000rpm at 100kph, and my old grand vitara with a G16B sat at around 3200, So the 5th gear probably sits a bit out of the efficiency band.

Primary consideration goes to 1st gear Low Range though.

Thanks for your help

Because you want the gearing to mostly benefit the lowrange gearing, Diff gears (vit CW&P 5.12:1) will not give you low enough final drive. (gwagensteve has figures somewhere)

Gearbox changes are not an option, to expensive and will ruin your highrange.

Lowrange reduction gears can be purchased from www.lowrangeoffroad.com
4.16, 4.9 or 6.5:1 ratios can be purchased.

i had 4.9's and 31s and it was good.
i now have 6.5's and 33 and its just as good.

they are around 800 or so delivered.

im running calmini 5.14 tcase gears in mine... 1600 EFI engine and 31" simex ETs... 100km/hr is about 3200rpm, 80km/hr is 2500rpm (5th).

Low range is brilliant - 5th gear near redline in low maxes about 45km/hr (tested onroad with front hubs unlocked).

i reckon 5.14 is about spot on for fixing 31s. a lot of guys go 6.5s though.