Viscous Coupler & Reseal Kit Combo Pack NP249J
with Full-Time 4WD Transfer Case
Please see the detailed description below for your specific model:
Jeep Grand Cherokee:
6 CYL 4.0L 1993 – 1994 NP249 (aluminum cases, chain driven, 24-mm wide input bearing (BD50-8)
6 CYL 4.0L 1993-2004 NP249 (aluminum cases, chain driven, 16-mm wide input bearing)
8 CYL 5.2L 1993 – 1994 NP249 (aluminum cases, chain driven, 24-mm wide input bearing (BD50-8)
8 CYL 5.2L 1995-1998 NP249 (aluminum cases, chain driven, 16-mm wide input bearing)
8 CYL 5.2L 1998 NP249 (aluminum cases, chain driven)
Jeep Grand Wagoneer:
8 CYL 5.2L 1993 NP249 (aluminum cases, chain driven, 24-mm wide input bearing (6010-N))
Viscous Couplings are located in the Model 247 and Model 249 Transfer Case Assemblies.
They are filled with a special fluid, along with sets of internal plates. The plates are connected to either the front or rear output shafts.
They are used to transfer torque from the rear wheel to the front, or visa versa, in the event that either set of wheels begin to slip.
When one set of wheels spins freely, the viscous fluid between the plates drags the slower set of plates along. This transfers torque to the wheels where it is needed!
The advantages of these units are not felt until wheels actually lose traction.
Because these units are filled with a viscous fluid, the viscosity of this fluid will break down over time. This occurs especially in hot climates, or severe use. When this happens, the effectiveness of 4WD is severely impaired.
Heat buildup inside the VC is both what can destroy it and what operates it.
Whenever the speed of the front and rear drive shafts does not match perfectly, the plates inside the VC are slipping in the internal fluids, creating heat. Minimizing that heat is the key to long life.
As always if you are unsure of specific fitment please send us a message and we would be happy to help!