The “Grind” of the Doubler: NP205 Rebuild Part 1

It’s finally happening! We’ve officially started the 203/205 Doubler build, and man, there is something so satisfying about cracking open a heavy-duty gear box. This project is all about the “Victory” of having an unstoppable crawl ratio, but right now, we’re knee-deep in the “Pain”—specifically, the greasy, needle-bearing-filled kind of pain.

The mission for this phase was simple: tear down the NP205 transfer case to swap out the small input shaft for a much beefier version. To make that happen, we had to bore out the bearing hole in the case to accept the larger bearing. It’s a bit of a commitment once you start cutting metal, but that extra girth on the input shaft is going to be well worth the effort when we’re out on the trail.

Tech Specs & Shop Notes:

• The “Girthy” Input: Swapped the old, small input for the upgraded heavy-duty version. This required machining the case for the larger bearing diameter [08:24].
• Shift Rail Upgrade: We went with JB Custom Fab stainless shift rails. These are ground specifically to allow for “front-wheel-drive only” or “rear-only” options (Twin Stick setup), which gives us way more flexibility on technical climbs [20:32].
• The Vaseline Trick: If you’ve ever messed with an NP205, you know the needle bearings (all 45 of them in the rear output!) are a nightmare. I used petroleum jelly to stick them in place during assembly. It holds them just long enough to slide the shaft in and then dissolves into the gear oil once things get moving [09:48].
• Seal it Up: Pro-tip—most of the bolt holes on these cases actually go all the way through. Even if you use fresh gaskets, I highly recommend a dab of RTV on the bolt threads to prevent those annoying “mystery leaks” later on [35:36].

I’ll be honest, this was my first time fully gutting a 205, and it was definitely more of a puzzle than I expected. Between the snap rings, the detent balls, and making sure the shift forks were oriented correctly (long side to the front!), it kept me on my toes. But that’s the beauty of the grind. Now that the 205 is sealed up and ready, we move on to the 203 range box.

We’re one step closer to that epic crawl ratio. If you’ve been sitting on a project because it looks too complicated, just remember: it’s just gears and grease. You’ll figure it out!

Wheel it, Wreck it, Wrench it, Repeat!