DIY: Rebuild the New Process 242 Transfer Case

    Good As New 242

    Jay KopycinskiPhotographer, Writer

    The NP242 transfer case was introduced in 1987 and provides the option of both full- and part-time function with four operating modes. The medium-duty transfer case is built using a cast-aluminum housing. It is quite similar in design to many other New Process chain-drive cases, however, an added differential assembly on the mainshaft allows for high-range 4WD use under any conditions. And, like all the other transfer cases, it has traditional, locked mode for typical part-time high-range and low-range 4WD operation.

    Weight of the NP242 is about 85 pounds, and the Jeep unit has a driver-side front output. High-range gearing is 1:1; low-range is 2.72:1.

    These transfer cases are quite durable when used under reasonable conditions. Long-term, severe use can cause the drive chain to stretch and the synthetic pads on the shift forks to wear. One of the common causes of failure is excessive wear due to lack of lubrication. The NP242 uses an internal oil pump to move lubrication where needed. When fluid levels inside drop due to a seal leakage or other reasons, the case can run hot and start to wear parts prematurely. Once the transfer case is opened up for repair, a magnet in a pocket at the bottom of the housing can be examined for signs of metal wear and debris.

    We completed our rebuild using mostly common mechanic tools on a home workbench, and did use a press on a couple of bearings. To do the job yourself, you will want a good set of flat-bill retaining ring pliers, a large socket for the front yoke, and likely an internal-type bearing puller. The Yukon kit from Randy's Worldwide provides replacements for the common wear items. While inside, you'll also want to inspect for chain damage or excessive wear, pump condition, and the condition of all internal gear components including the annulus gear inside the front case.