NP242 Transfer Case Drive Chain HV-028 Jeep Grand Cherokee

This is the drive chain that transfers torque from the mainshaft sprocket to the front output shaft sprocket inside a New Process NP242 transfer case. It is OE number HV-028: 1.00 in wide, .500 in pitch, 36 links, round-pin construction. It also fits the NP244 case. The NP242 is the full-time/part-time selectable unit used behind the 4.0L and 5.2L in the Jeep Grand Cherokee ZJ and WJ, Cherokee XJ, Wagoneer, and in Dodge applications running the same case.

Chain stretch is the normal wear-out mode on these units. It shows up as driveline slop and a clunk on and off the throttle, a growl or whine that follows vehicle speed rather than engine speed, and glitter in the fluid when you pull the drain plug. On a badly stretched chain the slack lets it slap the inside of the aluminum housing, and once it cuts a groove in the case you are buying a case half instead of a $100 chain. A chain that has gone soft also lets the front output lag under load, which reads to the driver as 4WD slipping or not engaging cleanly.

Bench work: drain the case, unbolt and separate the halves, then lift the mainshaft, front output shaft and chain out together as an assembly. The chain will not come off either sprocket by itself. Inspect both sprockets while it is apart, since a stretched chain wears the sprocket teeth to a hooked profile and a new chain on hooked sprockets will not last. Replace the case-half gasket or RTV bead and the output shaft seals on reassembly, then refill with the fluid the case calls for. Check the new chain for free play against the old one before it goes in: if the used chain has noticeably more slack when you hang both from the same sprocket, the diagnosis was right.