Jeep Cherokee (XJ): Description and operation. Diagnosis and testing. Removal and installation

Jeep Cherokee (XJ) 1984 - 2001 Service Manual > Transmission and transfer case > NV231 transfer case > Description and operation. Diagnosis and testing. Removal and installation

Description and operation

NV231 transfer case

DESCRIPTION

The NV231 is a part-time transfer case with a low range reduction gear system. The NV231 has three operating ranges plus a Neutral position. A low range system provides a reduction ratio for increased low speed torque capability.

The geartrain is mounted in two aluminum case halves attached with bolts. The mainshaft front and rear bearings are mounted in aluminum retainer housings bolted to the case halves.

OPERATING RANGES

Transfer case operating ranges are:

  •  2WD (2-wheel drive)
  •  4x4 (4-wheel drive)
  •  4 Lo (4-wheel drive low range

The 2WD range is for use on any road surface at any time.

The 4x4 and 4 Lo ranges are for off road use only.

They are not for use on hard surface roads. The only exception being when the road surface is wet or slippery or covered by ice and snow.

The low range reduction gear system is operative in 4 Lo range only. This range is for extra pulling power in off road situations. Low range reduction ratio is 2.72:1.

SHIFT MECHANISM

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. Range positions are marked on the shifter bezel cover plate.

IDENTIFICATION

A circular ID tag is attached to the rear case of each transfer case (Fig. 1). The ID tag provides the transfer case model number, assembly number, serial number, and low range ratio.

The transfer case serial number also represents the date of build.

Fig. 1 Fill/Drain Plug And I. D. Tag Locations
Fig. 1 Fill/Drain Plug And I. D. Tag Locations

1 - I. D. TAG
2 - FILL PLUG
3 - DRAIN PLUG

OPERATION

The input gear is splined to the transmission output shaft. The input gear drives the mainshaft through the planetary assembly and range hub. The front output shaft is operated by a drive chain that connects the shaft to a drive sprocket on the mainshaft.

The drive sprocket is engaged/disengaged by the mode fork, which operates the mode sleeve and hub. The sleeve and hub are not equipped with a synchronizer mechanism for shifting.

Lubricant and fill level

DESCRIPTION

Recommended lubricant for the NV231 transfer case is Mopart Dexron II, or ATF Plus 3, type 7176.

Approximate lubricant fill capacity is 1.2 liters (2.5 pints).

The fill and drain plugs are both in the rear case (Fig. 2). Correct fill level is to the bottom edge of the fill plug hole. Be sure the vehicle is level to ensure an accurate fluid level check.

Fig. 2 Fill/Drain Plug Locations
Fig. 2 Fill/Drain Plug Locations

1 - I. D. TAG
2 - FILL PLUG
3 - DRAIN PLUG

Diagnosis and testing

NV231 DIAGNOSIS

DIAGNOSIS CHART

Condition

Possible Cause

Correction
Transfer case difficult to shift or will not shift into desired range.
  1. Vehicle speed to great to permit shifting.
  2.  If vehicle was operated for an extended period in 4H mode on dry surface, driveline torque load may cause difficulty.
  3.  Transfer case shift linkage binding.
  4.  Insufficient or incorrect lubricant.
  5.  Internal transfer case components binding, worn, or damaged.
  1.  Slow vehicle and shift into desired range.
  2.  Stop vehicle and shift transfer case to Neutral position. Transfer case can then be shifted to the desired mode.
  3.  Repair or replace linkage as necessary.
  4. Drain and refill transfer case with the correct type and quantity of lubricant.
  5.  Repair or replace components as necessary.
Transfer case noisy in all drive modes.
  1. Insufficient or incorrect lubricant.
  1.  Drain and refill transfer case with the correct type and quantity of lubricant.
Transfer case noisy while in, or jumps out of, 4L mode.
  1. Transfer case not completely engaged in 4L position.
  2.  Transfer case shift linkage out of adjustment.
  3.  Transfer case shift linkage loose or binding.
  4.  Range fork damaged, inserts worn, or fork is binding on the shift rail.
  5.  Low range gear worn or damaged.
  1.  Slow vehicle, shift transfer case to the Neutral position, and then shift into the 4L mode.
  2.  Adjust linkage as necessary.
  3.  Repair, replace, or tighten linkage components as necessary.
  4.  Repair or replace components as necessary.
  5.  Repair or replace components as necessary.
Lubricant leaking from transfer case seals or vent.
  1. Transfer case overfilled.
  2.  Transfer case vent closed or restricted.
  3.  Transfer case seals damaged or installed incorrectly.
  1.  Drain lubricant to the correct level.
  2.  Clean or replace vent as necessary.
  3.  Replace suspect seal.
Abnormal tire wear.
  1. Extended operation in 4H mode on dry surfaces,
  1. Operate vehicle in 2H mode on dry surfaces.

Removal and installation

Transfer case

REMOVAL

(1) Shift transfer case into Neutral.

(2) Raise vehicle.

(3) Drain transfer case lubricant.

(4) Mark front and rear propeller shaft yokes for alignment reference.

(5) Support transmission with jack stand.

(6) Remove rear crossmember, or skid plate.

(7) Disconnect front/rear propeller shafts at transfer case.

(8) Disconnect vehicle speed sensor wires.

(9) Disconnect transfer case linkage rod from range lever.

(10) Disconnect transfer case vent hose (Fig. 3) and indicator switch harness, if necessary.

(11) Support transfer case with transmission jack.

(12) Secure transfer case to jack with chains.

(13) Remove nuts attaching transfer case to transmission.

(14) Pull transfer case and jack rearward to disengage transfer case.

(15) Remove transfer case from under vehicle.

INSTALLATION

(1) Mount transfer case on a transmission jack.

(2) Secure transfer case to jack with chains.

Fig. 3 Transfer Case Mounting
Fig. 3 Transfer Case Mounting

1 - VENT TUBE
2 - TRANSFER CASE
3 - TRANSMISSION

(3) Position transfer case under vehicle.

(4) Align transfer case and transmission shafts and install transfer case on transmission.

(5) Install and tighten transfer case attaching nuts to 35 N·m (26 ft. lbs.) torque (Fig. 3).

(6) Connect vehicle speed sensor wires, and vent hose.

(7) Connect indicator switch harness to transfer case switch, if necessary. Secure wire harness to clips on transfer case.

(8) Align and connect propeller shafts. Refer to Group 3, Differential and Driveline, for proper procedures and specifications.

(9) Fill transfer case with correct fluid. Check transmission fluid level. Correct as necessary.

(10) Install rear crossmember, or skid plate.

Tighten crossmember bolts to 41 N·m (30 ft. lbs.) torque.

(11) Remove transmission jack and support stand.

(12) Connect shift rod to transfer case range lever.

(13) Adjust transfer case shift linkage.

(14) Lower vehicle and verify transfer case shift operation.

Shift lever

REMOVAL

(1) Shift transfer case into 4L.

(2) Raise vehicle.

(3) Loosen adjusting trunnion locknut and slide shift rod out of trunnion (Fig. 4). If rod lacks enough travel to come out of trunnion, push trunnion out of torque shaft.

(4) Lower vehicle.

(5) Remove console. Refer to Group 23, Body, for proper procedures.

(6) Remove screws attaching lever assembly to floorpan and remove assembly and shift rod (if left attached).

INSTALLATION

(1) If shift rod was not removed from lever assembly, work rod down through floorpan opening. Then position lever assembly on floorpan and install assembly attaching screws.

(2) Install console. Refer to Group 23, Body, for proper procedures.

(3) Raise vehicle.

(4) Connect trunnion to torque shaft arm. Or, slide shift rod into trunnion on range lever. Be sure shift rod slides freely in trunnion.

(5) Verify that range lever is in 4L position. Then tighten trunnion lock bolt.

Fig. 4 Shift Linkage
Fig. 4 Shift Linkage

1 - RIVNUT (4)
2 - SHIFT LEVER ASSEMBLY
3 - FLOORPAN
4 - TRUNNION LOCK BOLT
5 - SELECTOR ROD AND TRUNNION
6 - SHIFT LEVER ROD
7 - TORQUE SHAFT FRAME BRACKET
8 - TORQUE SHAFT
9 - TRANSFER CASE SHIFT LEVER
10 - TORQUE SHAFT TRANSFER CASE BRACKET

(6) Lower vehicle and check transfer case shift operation.

Speedometer

REMOVAL

(1) Raise vehicle.

(2) Disconnect wires from vehicle speed sensor.

(3) Remove adapter clamp and screw (Fig. 5).

(4) Remove speed sensor and speedometer adapter as an assembly.

(5) Remove speed sensor retaining screw and remove sensor from adapter.

(6) Remove speedometer pinion from adapter.

Replace pinion if chipped, cracked, or worn.

(7) Inspect sensor and adapter O-rings (Fig. 5).

Remove and discard O-rings if worn or damaged.

(8) Inspect terminal pins in speed sensor. Clean pins with Mopart electrical spray cleaner if dirty or oxidized. Replace sensor if faulty, or if pins are loose, severely corroded, or damaged.

INSTALLATION AND INDEXING

(1) Thoroughly clean adapter flange and adapter mounting surface in housing. Surfaces must be clean for proper adapter alignment and speedometer operation.

(2) Install new O-rings on speed sensor and speedometer adapter (Fig. 5), if necessary.

(3) Lubricate sensor and adapter O-rings with transmission fluid.

(4) Install vehicle speed sensor in speedometer adapter. Tighten sensor attaching screw to 2-3 N·m (15-27 in. lbs.) torque.

(5) Install speedometer pinion in adapter.

(6) Count number of teeth on speedometer pinion.

Do this before installing assembly in housing. Then lubricate pinion teeth with transmission fluid.

(7) Note index numbers on adapter body (Fig. 6).

These numbers will correspond to number of teeth on pinion.

(8) Install speedometer assembly in housing.

(9) Rotate adapter until required range numbers are at 6 o-clock position. Be sure range index numbers correspond to number of teeth on pinion gear.

(10) Install speedometer adapter clamp and retaining screw. Tighten clamp screw to 10-12 N·m (90-110 in. lbs.) torque.

(11) Connect wires to vehicle speed sensor.

(12) Lower vehicle and top off transmission fluid level if necessary.

Front output shaft seal

REMOVAL

(1) Raise vehicle.

(2) Remove front propeller shaft. Refer to Group 3, Differential and Driveline, for proper procedure.

Fig. 5 Speedometer Components
Fig. 5 Speedometer Components

1 - SENSOR O-RING
2 - SPEEDOMETER ADAPTER
3 - ADAPTER O-RING
4 - SPEEDOMETER PINION
5 - ADAPTER CLAMP
6 - VEHICLE SPEED SENSOR

Fig. 6 Location Of Index Numbers On Speedometer Adapter
Fig. 6 Location Of Index Numbers On Speedometer Adapter

1 - SPEEDOMETER ADAPTER
2 - INDEX NUMBER LOCATION

(3) Remove front output shaft yoke.

(4) Remove seal from front case with pry tool (Fig.

7).

Fig. 7 Remove Front Output Shaft Seal
Fig. 7 Remove Front Output Shaft Seal

1 - OUTPUT SHAFT SEAL
2 - PRYBAR

INSTALLATION

(1) Install new front output seal in front case with Installer Tool 8143 as follows: (a) Place new seal on tool. Garter spring on seal goes toward interior of case.

(b) Start seal in bore with light taps from hammer (Fig. 8). Once seal is started, continue tapping seal into bore until installer tool seats against case.

Fig. 8 Front Output Seal Installation
Fig. 8 Front Output Seal Installation

1 - INSTALLER 8143
2 - TRANSFER CASE

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