STEP 1

After finding a model 300 transfer case that suits your application, the first thing to do is to drain all of the fluid, remove the shifter handle and inspection cover plate. Inspect the inside of the case. Look for any medal shavings, rust and anything else that might show damage to the internal gear assembly. Our kit does NOT require you to rebuild your transfer case, but if all shafts and gears do not spin freely or if they make a grinding noise, you might want to consider this before installation. Most of the transfer cases we see do not need rebuilding. Normally, a good cleaning, some fresh fluid and new seals (supplied) will be sufficient.

STEP 2

Using a ½” wrench, remove the 5/16” bolt holding the idler shaft retainer on the backside of the transfer case. Remove the bolt and retainer tab and save for later use. Using a punch and hammer, tap shaft through housing from front to back. Once the shaft comes out the other side, the idler gear and needle bearings will drop to the bottom of the case. These should be visible when looking through the inspection cover. There are 24 needle bearings on each side of idler gear bore, totaling 48 in all. There is a wide spacer in the middle, dividing the two sets of needle bearings and two thin spacers, one on each end of the idler gear bore. There are two thrust washers sandwiched between the idler gear and housing, one on each side as well. Upon removing the idler gear from the housing, make sure you have all of these pieces saved and cleaned for later use.

STEP 3

Using a 3/16” Alan wrench, look down into the case through the inspection plate and locate the two set screws holding the shift forks to the shift rails. Remove both set screws and save for later use.

STEP 6

Locate the two smooth bore holes on each side of the case where the shift rails went through the case. Using the ½” NPT drill bit, drill out all four holes to accept the ½” NPT tap. Using the ½” NPT tap, tap each hole all the way down until there are five threads left on the tap. This will insure proper sealing of the four supplied brass plugs. Install using the supplied Teflon tape.

STEP 7

Reinstall the front bearing retainer plate using a thin layer of RTV sealer (supplied) and three of the original retainer bolts. Using a little RVT, install the two-3/8” bolts (supplied) into each hole left vacant on each side of the two brass plugs. Use Loctite (supplied) on ALL fasteners in this transfer case.

STEP 8

After insuring the idler gear has been cleaned, reinstall the thick spacer in the center of the bore of the idler gear. Using Vaseline, coat the entire bore on each side of the thick spacer so that you can reinstall all 48 needle bearings. Install the needle bearings, one side at a time, using Vaseline to keep them in place. When both sides are complete, install the two thin spacers, one on each side, using more Vaseline to hold them in place. Using more Vaseline, install the two flat thrust washers inside the case. Make sure the thrust washer notches line up with the notch on each side of the case. Now slide the idler gear down into the housing, letting it sit on the bottom of the housing until a later step. Make sure that your needle bearings, two thin spacers and two flat washers stay in place.

STEP 9

Place the aluminum shifter plate on the inspection cover opening, insuring that the square corner of the plate is on the backside closest to the rear output shaft. At this time, use a bead of RTV sealer to seal the aluminum spacer to the housing. To temporarily hold the spacer in place, use two of the 5/16” x 2-1/4” bolts to keep the spacer from moving while the shift rails are being installed.

STEP 10

Take the new rear output shift rail and install it into the shifter plate in the sealed bore closest to the rear output shaft. Install shift rail, threads first, in from the rear of the case. As the shift rail is installed, install the new rear output shift fork, set collar facing the front of the case and slide the shift rail through the shift fork and line up set screw indention. Using one of your original set screws, install into rear output shift fork, making sure that set screw sits in the notch in the shift rail.

STEP 11

Before installing the other shift rail, pick up the idler gear from the bottom of the case and reinstall the idler gear shaft from the back of the housing. Be sure the thrust washers, two thin spacers and needle bearings have all stayed in place. Tap shaft all the way through, making sure that the notch on the shaft lines up the retainer bolt hole on the back of the case. Reinstall retainer and bolt at this time.

STEP 12

Remove the original shift pads on your original fork and replace with the two new ones supplied. Install front output shift rail, in the same manner as the rear, using your original shift fork. Be sure setscrew collar is facing the front of the case. Line up the center notch (neutral) with the poppet ball. Next line the shift fork up with center position in the case (neutral). Mark the shift rail and using a 3/8” drill bit make a notch in the rail for the set screw in the shift fork. Be sure it sits in the notch on the shifter shaft. Install the two ball bearings in the bores directly above the shift rails. Make sure each ball falls into one of the three notches on each shift rail. Next, install the four detent springs on the top of each ball bearing.

STEP 13

Now, using the original inspection cover, it is time to seal up the case. Make sure there’s no trash or medal shavings in the case. Remove the two bolts temporarily holding the shifter plate to the case. Apply a layer of RTV sealer to the top of the shifter plate. Make sure the detent springs stay in place. Reinstall the inspection cover plate using the 5/16” x 2-1/4” bolts and lock washers (supplied).

STEP 14

Remove plug in the inspection plate cover. Install the new brass nipple in its place, this is your new vent hose connection.

STEP 15

Remove the old vent hose tube from the rear bearing retainer. Using the supplied 7/16 drill bit, drill out the vent tube hole and tap using the ¼” NPT tap drill set supplied. After tapping the hole, install your old inspection cover plug using Teflon tape.

STEP 16

Remove the input bearing retainer. The input shaft and bearing retainer will be removed from the housing together. Once removed from the case, remove the snap ring that holds the input gear to the input shaft (press may be required). Now, remove the outer snap ring from the housing. Separate the bearing from the housing by lightly taping on the input shaft with a rubber mallet or equivalent. Once the housing is removed, using a press, remove the input bearing from the shaft and reinstall the new sealed bearing in its place.

STEP 17

There are six ridges on the input bearing retainer. Using the base of these ridges as your guide, use a hacksaw or sawsall to remove this material from the bearing retainer. This will eliminate the need for a spacer between the transfer case and transmission. Use a file or grinder to clean the edges after the cut is made. Use a thin layer of RTV sealer to coat the inside of the housing where the bearing will sit. This will insure the sealing of the input shaft. Using a rubber mallet or equivalent, reinstall the input shaft and the sealed bearing in the bearing retainer. Reinstall the large snap ring in the housing. Then reinstall the input gear on the input shaft and replace the snap ring onto the shaft. Using a thin coat of RTV sealer, reinstall the input bearing retainer into the housing.

STEP 18

Install the new output shaft seals in the case (supplied).

STEP 19

Using two 5/16” x ¾” bolts, install the new shift rail cover to the back of the shifter plate. Be sure to use RTV sealer on the housing edge that contacts the shifter plate.

STEP 20

Your new drain plug is located on the backside of the housing beside the two brass plugs. This was the old fill plug.

STEP 21

At this time, remove your stock transfer case from your Wrangler. Remove your skid plate and support the transmission with a jack. Remove the shifter linkage and the shifter assembly from the vehicle. Next, disconnect all wires from the case and remove both drive shafts. Finally, unbolt the case from the transmission. Remove the speedo gear from the 300 transfer case and replace with the speedo sensor from you NP 231-transfer case. Be sure to clock the new speedo gear to insure that it contacts the worm gear on the output shaft of the 300 case.

STEP 22

Before installing your model 300 in your Jeep, it is necessary to remove your old transmission output seal. The matting of the transfer case will now seal the transmission.

STEP 23

Upon completion of the Flip Kit, test fit your transfer case to your transmission. If the transfer case does not slide up flush with the transmission housing, it may be necessary to trim approximately 3/8” from the transmission output shaft. DO NOT remove any more than necessary to achieve a flush mount, yet make sure it does NOT bottom out in the transfer case.

STEP 24

Using the transfer case gasket (supplied), line up the four bottom holes on the transmission. This should leave the top two holes slightly off. Using a 3/8” drill bit, mark and drill these top two holes to ensure use of all 6-bolt holes.

STEP 25

Now you can install your transfer case. Make sure both matting surfaces are clean and free of oil and dirt. Using a thin layer of RVT, coat the transmission output housing. Next, install the 6-hole transfer case gasket. Coat the gasket with a thin layer of RVT. Install the case, making sure all 6 holes are aligned. Install the 2 fine thread nuts (factory) on the 2 transfer case studs. Use the four (4) 3/8” bolts and loc-washers on the other 4 bolt holes. Be sure to use the Loctite supplied. Also,
Be sure to plug the factory hole in the transmission
adaptor housing. This is located at the rear of the
transmission, near the bottom of the mating surfaces.

STEP 26

Using the instruction sheet supplied with shifter, install shifter assembly.

STEP 27

Remove fill plug from shifter plate and fill transfer case with two (2) quarts 80w-90 gear oil. Yes, that’s right. No special oil to have to worry about!!

STEP 28

Install your new rear drive shaft and have your front shortened. The yoke’s on a model 300 use the same straps as a YJ/TJ. Also, the 300 can be upgraded to use u-bolt retainers instead of the weaker straps.

STEP 29

After final installation of your transfer case and shifters, be sure that the shifters do not contact the body in any shifter position. Also, test all the shift movements of the case while driving to be sure the torque of the motor does not force the shifters into the body. Change the fluid in the case after 500 miles.

STEP 30

Two high: right shifter in the rear position, front shifter in neutral.
Four high: both shifters in rear position.
Four low: both shifters in the front position.
Two low: right shifter in the front position, left shifter in neutral.
Two low front wheel drive: left shifter in the front position, right shifter in neutral
Neutral is both shifters in the center position