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|1994+ Ram Transfer Case Specs|
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231HD, 241D, & 241HD Transfer Cases
|NV Gear Transfer Case Specifications|
Ratios: L = 2.72, H = 1.00
Fill and drain plugs: 10mm Hex wrench
Mopar Dextron II, or ATF Plus type 7126 automatic transmission fluid.
NV241 vacuum switch part number: 53001101 at Dodge parts
The NV231 and 241 are part time transfer cases with a low-range gear system. They have three operating ranges plus a Neutral position. The low range (4L) position provides a gear reduction ratio of 2.72:1 for increased low speed torque capability. NV241 operating ranges are: 2-high, 4-high, and 4-low. Transfer case operating ranges are selected with a floor-mounted shift lever. The shift lever is connected to the transfer case range lever by an adjustable linkage rod. A straight line shift pattern is used.
On the NV transfer case, the gear cases, retainer, and extension are all of aluminum. Drive sprockets and an interconnecting chain are used to transmit engine torque to the front and rear propeller shafts. The mainshaft, input gear, and front output shaft are supported by ball and needle bearings.
A synchro mechanism consists of a brass stop ring, synchro hub with three struts and two retaining springs, and the sliding clutch. The synchro components allow the transfer case to be shifted between 2H and 4H ranges while the vehicle is in motion. However the vehicle must be stopped or moving very slowly to shift into 4L range. Four wheel high and low ranges are undifferentiated. The transfer case is not designed for continuous operation in 4WD range on hard or paved roads. 4WD ranges are recommended for off road operation, or on snow covered or similar low traction surfaces.
A front axle disconnect system is used to achieve 2WD mode. The axle disconnect vacuum motor is actuated by a vacuum switch on the transfer case. The switch is operated by the transfer case range rod.
Transfer case versions: NV231, NV231HD, NV241, NV241D, NV241HD
The NV231 transfer case is used behind many V6 and V8 engines in pickups and sport utility vehicles.
The NV231HD, used in the 1994+ Ram with V6 and V8 engines, features larger bearings and a wider chain than the NV231. All versions of the 231 cases use three gears in the planetary reduction set.
The NV241 is essentially a NV231HD with six gears in the planetary set.
The NV241D is a heavier duty Dodge version of the 241, with a larger input shaft and larger bearings to withstand the torque of the V10 and diesel engines.
The NV241HD, an option on Ram 2500's and standard on Ram 3500's built after 1998, has a stronger case and wider drive chain to better withstand the shock of snow plow service, a PTO cover and drive gear, and an extra bearing to support the thrust to the main shaft created by a PTO adapter.
Except for dimensional differences and the PTO port on the NV241HD, all of the cases are almost identical in appearance. An identification tag is attached to the rear case of every transfer case. The tag provides the transfer case model number, assembly number, serial number, and low range ratio. The transfer case serial number also provides the date of build. For example, a serial number of 9-10-93 would represent September 10, 1993.
There is a great Transfer Case Identification Guide (pdf) on the ATRA and GEARS magazine site =
Last Update November 13, 2002