NP228/NP229
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NP228/NP229
The NP228/229 transfer cases were Jeeps first transfer cases to receive the "Selec Trac" name, the later Selec Trac transfer case being the NP242. Both the NP228 and NP229 offer 2 wheel drive, Full Time 4 wheel drive in High range and Part Time 4 wheel drive in Low range. The NP228 uses an open differential for its front/rear power split in 4WD Fulltime High, the NP229 uses viscous coupling for its front/rear split in 4WD Fulltime High. Both lock the front/rear output shafts in 4 wheel drive in Low range. Both lack a 4 wheel drive Part Time High range mode.
The NP228 was offered in '85-'87 XJ Cherokees.
The NP228/229 use 2 controls for its various modes. A vacuum switch controls 2 wheel drive or 4 wheel drive. A shift lever controls High or Low range.
NP228/229 Selec Trac features:
- 2 wheel drive - for all road conditions.
- 4 wheel drive full time high - for all road conditions including dry pavement.
- Neutral - disengages front and rear driveshafts.
- 4 wheel drive part time low - for *off road* conditions with low traction conditions and extra pulling power is needed. NOT FOR USE ON DRY PAVEMENT as transfer case damage may result.
OPERATION
Because Selec-Trac control functions are interrelated, mode switch and range lever must be used in specific combinations to operate the transfer case.
With range lever in the HI range, select either 2-wheel drive (2WD) or full time 4-wheel drive (4WD) by moving the mode switch. Mode selection can be made *WHILE THE VEHICLE IS MOVING AT ANY LEGAL SPEED.*
NOTE: If mode switch is moved from one position to another
while the vehicle is not moving, it may be necessary to move
the vehicle forward or backwards slightly for the transfer case
to fully engage 4WD, expecially in cold weather.
If mode switch is in 4WD and the transfer case has completed the shift, Selec-Trac offers a choice of HI, N, or LO ranges by moving range lever. Range shifts must be made *ONLY AT LOW SPEED 2-3 MPH, 3-5 KM/H)*.
CAUTION: Never attempt to engage LO range when vehicle
is in 2WD or when vehicle is moving faster than 2-3 mph (3-5
kmh). Transfer case damage may result.
*WARNING: NEVER PARK YOUR VEHICLE WITH RANGE LEVER IN THE
N (NEUTRAL) POSITION. THE VEHICLE COULD ROLL UNEXPECTEDLY
EVEN IF AN AUTOMATIC TRANSMISSION IS PLACED IN PARK OR A
MANUAL TRANSMISSION IS IN GEAR.*
Mode Selection (2WD/4WD) - Mode switch allows you to select 2WD or 4WD whenever you wish, as long as range lever is in the HI range position.
NOTE: Complete transfer case engagement into HI must be
made before you can or should attempt to engage 2WD.
Range Shifts (HI-N-LO) - Range lever allows you to shift to HI, N, or LO range when the transfer case is fully engaged in 4WD, the vehicle is moving slowly (2-3 mph) and the *TRANSMISSION* is shifted to neutral.
CAUTION: Do not try to move range lever from HI to LO when
mode switch is in the 2WD position. The range lever shift linkage
could be damaged.
- HI position - 2WD or 4WD--In either position, the vehicle may be operated on all road surfaces. In 4WD, Select Trac offers better traction when roads are wet, snow covered or icy. Use Selec-Trac 4WD year-round (full time) if you wish.
- N Position (Neutral) - In this position the axles are disengaged from the powertrain. The vehicle may be towed without removing the propeller shafts. Place an automatic transmission in Park or a manual transmission in gear after the N position is engaged
- Lo Position - This position provides 4WD for occasional use when *OFF-ROAD* driving conditions require low speed pulling power.
WARNINGS / CAUTIONS
*WARNING: DO NOT DRIVE THE VEHICLE UNLESS THE TRANSFER CASE
IS FULLY ENGAGED. FAILURE TO COMPLETELY ENGAGE A POSITION
CAN CAUSE TRANSFER CASE DAMAGE OR LOSS OF POWER AND VEHICLE
CONTROL. BE SURE YOU KNOW THE SHIFT PATTERN OF YOUR VEHICLE.*
*WARNING*: DO NOT INSTALL SELECTIVE DRIVE HUBS ON SELEC-TRAC
VEHICLES. IF THESE HUBS ARE LEFT UNLOCKED WHEN THE VEHICLE
IS PARKED, THE VEHICLE COULD ROLL UNEXPECTEDLY--EVEN IF AN
AUTOMATIC TRANMSISSION IS IN PARK OR A MANUAL TRANSMISSION
IS IN GEAR.*
*WARNING: NEVER PARK YOUR VEHICLE WITH RANGE LEVER IN THE
N (NEUTRAL) POSITION. THE VEHICLE COULD ROLL UNEXPECTEDLY
EVEN IF AN AUTOMATIC TRANSMISSION IS PLACED IN PARK OR A
MANUAL TRANSMISSION IS IN GEAR.*
CAUTION: Do not try to move range lever from HI to LO when
mode switch is in the 2WD position. The range lever shift linkage
could be damaged.
CAUTION: Never attempt to engage LO range w when vehicle is moving
faster than 2-3 mph (3-5
kmh). Transfer case damage may result.
