[Bitcoin Man]

ATC 300 Transfer Case Internal Parts and Operation.

The ATC 300 has a main shaft (there are oil passages within the shaft) from the input (transmission) to the output (rear drive shaft). The main shaft rotates on two ball-type bearings. Starting from the input side of the main shaft, we have needle roller bearings, then the sprocket assembly (sprocket and multi-plate clutch (mpc)), the clutch drum, and the oil suction pump.

The sprocket assembly is composed of a sprocket, needle bearings, 2 mpc actuator arms, the mpc pressure plate, mpc shims, mpc hub, 6 friction disks and 7 steel disks. The needle bearings allow the sprocket to rotate independently of the main shaft. The 2 clutch arms are separated by 5 steel balls. There are inclined grooves cut within the arms; when the arms are rotated apart (The 2 mpc arms rest on opposite sides of a cam. The rotation of the cam, causes the mpc arms to rotate apart. The set positioning motor has a small gear the rotates the gear on the cam, which, causes the mpc arms to rotate apart), the arms are pushed apart slightly; this separation of distance causes the upper clutch arm to push up against the mpc pressure plate, which clamps together the fiction and steel discs. The steel disks are splined to the clutch hub, which is part of the sprocket. The fiction disks are splined to the clutch drum; the drum is splined to the main shaft. Whenever the mpc is engaged, the torque is transmitted from the main shaft, to the mpc drum, to the mpc friction disks, to the mpc steel disks, to the mpc hub, and then to the sprocket – which causes the sprocket to rotate around the main shaft on the needle bearings. The mpc sprocket is connected to the intermediate sprocket, and then to the final output sprocket; which is connected to the front drive axle.

On top of the mpc drum, sits an oil suction pump, which has a suction tube to the lower transfer case house, where the oil sits. Rotation of the mpc drum, causes a disk to rotate within the oil pump, creating suction, which draws the oil to the oil pump and outwards to the mpc and other parts inside the transfer case. Sitting at the bottom of the transfer case is a magnet.

There are 3rd party suppliers that have all the parts needed to repair the ATC 300 transfer case. Parts that may fail or wear out include the 2 needle bearings that rest above and below the mpc arms and the friction disks. The main shaft ball bearings and output shaft (to front driveshaft) ball bearings may also wear out too. The input and two output oil seals may need replacing too, as well as the transmission engine mount. The transfer case can be sealed with Permatex Ultra Grey or compatible gasket maker.

There are 6 bolts that attach the transfer case to the automatic transmission. Two bolts on the driver’s, facing the front of the car. 2 bolts on top of the transfer case and 2 bolts on the passenger side, both facing the rear of the car. After the driveshaft has been removed from the transfer case, the transfer case can be lowered slightly to reach the top two bolts (actually, the front motors mounts are strong enough to support the engine, transmission and transfer case; however, it’s wisely to support the transmission with a jack. Once the bolts are removed, you can use a rubber hammer and pound on the transmission mount to help separate the transmission shaft from the transfer case (slightly lifting the transfer case without causing lift on the transmission with help in the removal too). The transfer case weights about 60-lbs. If you don’t have a transmission jack, I highly advise you to put a box with newspapers to cushion the an accidental fall of the transfer case. Also, I advise do not go cheap on the jack stands; I have 4 20-ton jack stands from harbor freights (Since these jack stands are high, the jacking procedure I use is jack up the front of the car on smaller jack stands, then jack up the rear of the car on the 20-ton jack stands, and then jack up the front of the car again, remove the smaller jack stands, and then replace with 20-ton stands).