The Jeep Technical Transfer Case pages cover stock transfer cases used
in Jeeps from 1941 until the present and they cover transfer case
upgrades. Low gear swaps in transfer cases and transfer case swaps
are covered in great detail.
Transfer Case Upgrades
Project Comanche - Fixed Yoke Kit
The Comanche driveline gets an update with the addition of an SYE kit. Installing a suspension lift
and big tires has an effect on every related component and will often find your vehicle's weakest
link and exploit it. If this happens out in the wilderness, it can make for a long day. I'll take
the convenience of floorjacks and air tools instead of blocking the middle of the trail.
NP231 Transfer Case Upgrade to NP231HD w/JB SYE
My new NP231HD/DHD is a zero-mile unit manufactured for Dodge trucks. It came from New Venture Gear
through JB Conversions who added their short shaft kit (SYE) and converted the shift sector from
Dodge to Jeep. The Heavy Duty designation is because of the large syncro hub and wider chain. In
addition, JB Conversions replaced the stock 3-gear input pinion to the stronger 6-gear pinion. This
new NP231 transfer case is the strongest it will ever be, and makes an easy upgrade for many Jeeps.
JB Conversions Heavy Duty NP231
The JB Conversions NP231HD unit is an excellent upgrade for anyone that owns
a Wrangler or Cherokee with a transfer case problem. The JB Conversions
zero-mile NP231HD unit comes complete with a larger bearing, wider chain, and
a slip-yoke eliminator kit already installed.
Project SkyMiles "Phase II"
Project SkyMiles "Phase II" is a combination of upgrades designed to strengthen the Cherokee XJ,
make it more versatile, and position the Jeep for future upgrades. The main pillars of Phase II
are the addition of a Klune-V 4:1 planetary underdrive and the switch to a Dana 44 rear axle.
The upgrade was far from a simple two-step upgrade, however.
Installing a
TeraLow 4:1 kit in a NP231 Transfer case Installing lower gears will help your crawl
ratio, but often times sacrificing highway performance. Installing a 4:1 kit
will give your rig a much lower crawl ratio while retaining some of its on-road
performance.
Tera Low Gears for Dana 20 and 18
Tera Mfg makes a kit to give your Dana 20 a 3.15:1 low range. This translates to roughly 50% slower crawling for Jeep Dana 20s, without hurting street driveability. The install is suprisingly easy and the results are fantastic.
Reindexing a Transfer Case
Jim O'Brien reindexes his Dana 300 transfer case and ends up with a completely
flat skid plate. Reclocking a transfer case is not as hard as you would
think.
Teraflex 2Low231 Kit
This kit will free up the front axle for better steering while keeping your low range. Now
you can choose between either 4 Low or 2 Low. The
2Low231 kit provides a mechanical disconnect for the front and rear output shafts while in
the neutral shift position, thus allowing for a "true neutral".
Transfer Case Swaps
Pieces & Parts Transfer Case
Project Pieces & Parts gets a Scout 80 Dana 18 transfer case. The Scout 80
Dana 18 is a small hole Dana 18 with the big intermediate shaft.
Other Gearing Options
Pieces & Parts Overdrive
A Warn Overdrive from a Scout 80 for Project Pieces & Parts. The Warn
Overdrive does not shorten the rear driveshaft and it provides a 0.75:1
gear reduction in all forward and reverse gears.
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