| The Select Trac option on the Jeep Cherokee | | | | mode at any speed simply by moving the lever. |
| gets you the New Process NP 242 transfer case. | | | | The switch to low range must be made at very |
| This transfer case gives the following operating | | | | low speed - the Jeep manual says 3 mph.One |
| modes: 2wd, 4wd with the center differential | | | | common operating problem with the 242 transfer |
| open, 4wd with the center differential locked, | | | | case is that it will stick in 4wd even if the lever is |
| neutral, and 4wd low range (center differential | | | | moved to 2wd. Internally, moving the lever loads |
| locked)The addition of a center differential is the | | | | a spring which then applies force to move the |
| main difference between the NP 242 and the NP | | | | selector fork. If the gears are loaded with torque, |
| 231 or Command Trac transfer case. Without a | | | | the spring will not have enough energy to move |
| differential, the 231 transfer case offers only part | | | | the sleeve off the gears. Once torque is removed |
| time four wheel drive mode.The NP 242 transfer | | | | from the gears, the spring will then move the |
| case Full time mode opens the center differential | | | | fork and slide the sleeve of the gears.Momentarily |
| allowing the front and rear axles to rotate at | | | | lifting your foot off the gas will often unload the |
| different speeds while still being linked by the | | | | gears enough to allow the spring pressure to |
| transfer case. The end with the least traction will | | | | move the fork. On some high mileage units, a |
| get the most torque. While this mode may have | | | | wear groove will form on the sleeve or gear |
| some disadvantages off road where a wheel may | | | | causing it to stick longer and may require a couple |
| loose contact with the ground, it has the | | | | of changes from loaded to unloaded to get the |
| advantage of being usable on all paved surfaces. | | | | sleeve to release form the gear.The Jeep NP 242 |
| Part Time mode - with the center differential | | | | is lubricated with Automatic Transmission fluid. |
| locks can only be used on loose or slick surfaces | | | | The level is checked by removing the upper of |
| with out possible damage to the transfer case.I | | | | the two large plugs on the back of the case. The |
| use full time mode on wet streets, hard packed | | | | fluid should be level with the upper plug.The NP |
| gravel or dirt, some snow and ice situations and | | | | 242 has a slip yoke on the tail shaft. If the drive |
| on dry pavement when full acceleration without | | | | shaft is damaged or removed, fluid will be lost out |
| wheel spin is desirable. I use part time mode on | | | | the tail shaft. Also this seal is important to |
| loose gravel, dirt, grass and any off road situation. | | | | maintain in good condition to prevent fluid loss.The |
| I use Part time mode when RallyCross racing as | | | | NP 242 is a very versatile transfer case and is |
| well.I use low range for more control in off road | | | | my choice for three of my five Jeeps. The full |
| situations or on rough gravel roads when traveling | | | | time selection gets frequent use in all of |
| downhill to avoid excessive use of the brakes. I | | | | them.Mike Strawbridge is the owner of Straw |
| also often use low range when positioning my | | | | Solutions Performance Consulting where he |
| trailer or other towed equipment when precision | | | | teaches others how to get the most |
| placement is needed.The NP 242 transfer case | | | | performance out of their business process. |
| can be switched between 2wd and either 4wd | | | | |