Overhaul - New Process 205 GMC Cab & Chassis R3500

IDENTIFICATION

An identification tag is located on driver's side of transfer case, on power take-off cover. Information on tag consists of model number, low range reduction ratio and assembly number.

DESCRIPTION

The New Process Model 205 is a heavy duty, part-time unit with constant mesh, helical gears. Gears are mounted in a one-piece cast iron case.

SHIFT LINKAGE ADJUSTMENT

Shift transfer case to Neutral position. Remove shift boot screws. Raise shift boot for access to shift bracket bolts. Loosen shift bracket bolts, and move bracket forward as far as possible. Tighten bolts and check shift linkage operation. Install shift boot.

Removal

1. Raise vehicle, and drain transfer case fluid. Disconnect vehicle speed sensor wires. Remove skid plate, crossmember and strut rods as needed. Disconnect drive shafts and wire aside. DO NOT allow drive shafts to hang free, as damage to "U" joints may result.
2. Disconnect shift lever rod from range lever. Support transfer case. Remove nuts attaching transfer case to transmission adapter. Move transfer case to rear until input shaft clears adapter. Lower transfer case from vehicle.

Installation

1. Install NEW transfer case-to-transmission gasket. Apply sealer to both sides of gasket. Ensure transfer case input splines align with transmission output shaft. Align splines by rotating output yoke. NOTE: DO NOT install transfer case-to-transmission nuts until transfer case is completely seated.
2. To complete transfer case installation, reverse removal procedure. Ensure all attaching bolts are tightened to specification. See «TORQUE SPECIFICATIONS»(/gmc/cab-chassis-r3500/1987-1991/remont/transfer-case/#overhaul-new-process-205) . Fill transfer case with lubricant.

Note. For exploded view of transfer case assembly (Scheme 22)

Scheme 19

1. Loosen rear output shaft yoke nut. (Scheme 22) Remove rear output shaft housing and retainer from case. Remove yoke nut, washer, seal washer and rear yoke from shaft. Remove rear retainer, rear output shaft and gears as an assembly from housing. Remove rear seal retainer from bearing retainer. Remove and discard snap ring.
2. Remove rear bearing retainer. Remove rear output shaft bearing, speedometer gear, shaft support bearing, thrust washer pin and low gear from rear output shaft. Remove lock ring, thrust washer and pilot bearing rollers from rear output shaft. (Scheme 22)
3. Remove front yoke nut, washer and flange. Remove front seal retainer and gasket. Remove power take-off cover and gasket. Remove detent plug and 4WD indicator light switch from case. Remove shift rail detent springs and balls. Use pencil magnet to remove as necessary.
4. Remove bolts attaching front bearing retainer to case. Tap front output shaft with plastic mallet to loosen. Remove shaft, retainer and gears. (Scheme 19) Remove shaft snap ring. Remove thrust washer, gear, bearings and spacer.
5. Remove transfer case adapter and gasket. Remove idler shaft nut and washer. Remove idler shaft cover and gasket. Remove cup plugs at top of case for access to shift fork lock pins. Use small punch to remove plugs. Place shift rails in Neutral position.
6. Remove lock pins from shift forks with long handle easy out. Remove pins attaching shift rail link and remove link. Remove shift forks and sliding clutches. Remove snap ring, thrust washer and bearing from front output shaft. Remove front output shaft and high gear.
7. Remove input gear, bearings, seals and washer. Loosen and remove idler shaft with soft-faced mallet. Tilt case, roll idler gear toward front output shaft opening in case, and remove gear through opening. Remove and retain idler gear shims. Keep shims together.
8. Remove bearing races and bearings from idler gear. Remove interlock pins from inside case. Remove pins through power take-off cover opening. If front output shaft rear bearing must be replaced, replace bearing and retainer as an assembly.

Cleaning & Inspection

1. Clean all parts with solvent, and blow parts dry with compressed air. DO NOT spin dry bearings. Remove all traces of gaskets from surfaces.
2. Inspect teeth of all gears for excessive wear or damage. Replace gear(s) if these conditions exist. Check for sliding clutch wear on engagement side. If wear exists, use opposite side of clutch in reassembly. Both sides of clutch are identical.
3. Carefully examine splines and shaft for scoring or evidence of wear. Sliding clutch gears must move freely on splines. Parts should be replaced if spline or shaft is scored or heavily worn.

Note. For exploded view of transfer case assembly (Scheme 22)

Scheme 20

1. Lubricate transfer case gears and shafts with gear oil during reassembly. Use petroleum jelly to lubricate and hold bearings in place during installation. Use NEW gaskets and seals. Replace snap rings if distorted or damaged. Use NEW yoke lock nuts to secure yoke and flange.
2. Using a press, install bearing races in idler gear. Assemble idler gear, gear bearings, bearing spacer and shims on dummy shaft with bore facing up. Check idler gear end play. (Scheme 20) End play should be 0-.002" (0-.005 mm).
3. Press shift rail oil seals into case. Seals should be installed with seal lip facing outward. Install idler gear assembly and dummy shaft into case. Insert assembly through front shaft bore, large end first. Tilt case at 45 degree angle to ease bearing installation.
4. Install idler shaft. Insert shaft from large bore side and tap shaft into gear and bearings with soft-faced hammer. Remove dummy shaft as idler shaft pushes shaft out of gear and case. Install idler shaft washer and NEW lock nut. Check for end play and free rotation. Tighten lock nut to specification. See «TORQUE SPECIFICATIONS»(/gmc/cab-chassis-r3500/1987-1991/remont/transfer-case/#overhaul-new-process-205).
5. Install front bearing and lock ring on input shaft. Assemble front output shaft. Install gear, sliding clutch, bearings, thrust washer pin, thrust washers, snap ring and retainer on front output shaft. (Scheme 22) Install interlock pins through large bore of power take-off opening. Install input gear into case.
6. Install sliding clutch on input gear and position shift fork in sliding clutch. Install rear wheel shift rail into case with slotted end first and detent notches facing up. Push rail through shift fork and into opposite end of case. Install front output shaft into case. Install front wheel shift fork in sliding clutch on front output shaft.
7. Install front wheel shift rail into case and through shift fork. Secure shift forks to shift rails with NEW lock pins. Install pins through small bores at top of case. Install front output shaft bearing retainers. (Scheme 22) Prior to tightening retainer bolts, ensure oil drain slot in bearing retainer is aligned with drain hole in case. Use NEW gaskets and apply sealant to retainer bolts threads. Tighten bolts to specification. See «TORQUE SPECIFICATIONS»(/gmc/cab-chassis-r3500/1987-1991/remont/transfer-case/#overhaul-new-process-205).
8. Install flange on front output shaft. Install seal washer on shaft and install flange lock nut finger tight. Install washer, seal, gasket and adapter on input shaft. Install shift link and link retaining pins and clips.
9. Assemble rear output shaft. Install gear, bearings and spacers. (Scheme 22) Install NEW snap ring. Tap snap ring to seat and check end play. End play should be.002-.027" (.51-.69 mm). Grease pilot bearing bore of rear output shaft. Install pilot bearing rollers (15) in rear output shaft. Use petroleum jelly to secure rollers.
10. Install pilot bearing thrust washer and NEW lock ring. Install retainer on rear output shaft. Install speedometer gear and spacer. (Scheme 21) Install rear output shaft support bearing. Install retainer and shaft assembly. Ensure oil drain slot in retainer is aligned with drain hole in case. Tighten retainer bolts to specification.
11. Install seals in front and rear retainers. Position gaskets on case and install retainers over shafts against case. Tighten retainer bolts to specification. Install yoke and flange. Install NEW lock nuts and tighten to specification.
12. Install detent balls, springs, plugs, cup plugs and 4WD indicator light switch. Install drain plug. Fill transfer case to bottom edge of fill plug hole with appropriate lubricant. Install fill plug.

Scheme 21

Scheme 22

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• TORQUE SPECIFICATIONS