Overhaul - New Process 208 GMC Pickup R1500

DESCRIPTION

The Model 208 is a part-time 4WD unit having an integral 4WD-Low range. This model is a 4-position unit, providing 2 gear ratios in 4WD (High and Low), a 2WD-High and Neutral.

A chain drive is used with front and rear output shafts mounted in ball and roller bearings. Two drive sprockets and a planetary gear assembly, consisting of a 4-pinion carrier and annulus gear, are housed in a 2-piece aluminum case. All models have manual locking hubs as standard equipment and 4WD indicator lights. These lights inform the driver of the operating mode of the vehicle.

SERVICE INTERVALS

Check fluid level. Case should be filled to edge of fill plug opening. Add fluid as necessary every 4 months or 6000 miles. Drain and refill transfer case every 36,000 miles.

All Models

Use Dexron II ATF.

Chrysler Motors

Capacity is 6 pts. (2.8L).

Ford Motor Co.

Capacity is 9 pts. (4.3L).

General Motors

Capacity is 10 pts. (4.7L).

ADJUSTMENTS

Adjust shift linkage so that all positions may be selected without interference or binding. Inspect all swivels, rods and mountings for wear or damage. Replace as necessary.

WILL NOT SHIFT OR DIFFICULT TO SHIFT INTO GEAR

Vehicle speed to high. Slow vehicle to 2-3 MPH to shift. Vehicle operated too long on dry paved surface. Stop vehicle and place in Reverse or Neutral to relieve driveline torque. Ensure transfer case external linkage is not binding. Ensure correct fluid is used. Worn or damage internal parts.

NOISY IN ALL GEARS

Check fluid level. Ensure correct fluid is used. If fluid is okay, locate noise.

JUMPS OUT OF GEAR OR NOISY IN 4WD

Transfer case not completely in gear. Check shift linkage. Range fork damaged. Inserts are worn. Shift fork binding on shift rail. Low range gear worn or damaged.

FLUID LEAKING FROM VENT OR SEALS

Transfer case overfilled. Vent plugged. Output shaft seals are damaged or not installed properly.

ABNORMAL TIRE WEAR

Vehicle operated on dry pavement in 4WD for extended periods.

Removal & Installation

1. Raise vehicle and support. Drain transfer case. Mark propeller shaft positions for installation purposes. Disconnect propeller shafts. Disconnect speedometer cable and all electrical wires.
2. Disconnect shift linkage. Remove heat shield and skid plate (if equipped). Support transfer case with a jack. Remove transfer case from vehicle. To install, reverse removal procedure.

Scheme 7

Scheme 8

1. Remove fill and drain plugs. Remove front and rear yokes. Discard yoke seal washers and nuts. Place transfer case on end and position front case on wood blocks. It may be necessary to cut "V" notches in wooden blocks to clear mounting studs in front case.
2. Remove lock mode indicator switch and washer. Remove detent bolt, spring and ball. Mark rear retainer and case for assembly alignment reference. Remove rear bearing retainer and pump housing as an assembly. Use mallet to remove retainer from case. DO NOT pry on retainer. (Scheme 7)
3. Remove pump housing from retainer and pump seal from housing. Discard pump seal. Remove speedometer drive gear from mainshaft. Remove oil pump from mainshaft. Mark position of pump for reassembly. Side of oil pump facing case interior is recessed. Remove bolts attaching rear case to front case. Remove rear case. NOTE: To remove rear case, insert screwdrivers into slots in case ends and gently pry upward. DO NOT pry case halves apart at any point on mating surface.
4. Remove front output shaft rear thrust bearing assembly. Mark position of bearing and races for reassembly. Remove driven sprocket retaining snap ring, drive sprocket retaining snap ring, and thrust washers.
5. Remove sprockets, mainshaft, mode fork and drive chain as an assembly. Lift evenly on both sprockets to remove. Remove front output shaft front thrust bearing assembly. Remove synchronizer assembly and snap ring. (Scheme 10)and (Scheme 11).
6. Remove drive sprocket and thrust washer as an assembly. DO NOT lose needle bearings (120 each) from within drive sprocket. On Ford models, remove sprocket carrier snap ring and clutch spring. (Scheme 11)and (Scheme 12).
7. Disassemble synchronizer assembly. Record part locations for reassembly purposes. Remove annulus gear retaining ring and thrust washer. Remove annulus gear and range fork as an assembly. Turn fork clockwise to disengage fork lug from range sector, and lift assembly out of case. Remove planetary thrust washer and planetary assembly.
8. Remove mainshaft thrust bearing from input gear. Remove input gear by lifting straight up and out of case. Remove input gear thrust bearing and race. Note position of bearing and race for reassembly. Remove range sector operating lever nut and washer.
9. Remove lever, sector shaft seal and seal retainer. Remove range sector. Inspect lock plate. If lock plate is loose, worn or cracked, remove lock plate. See «LOCK PLATE»(/gmc/pickup-r1500/1987-1987/remont/transfer-case/#overhaul-new-process-208) in this article. Remove output shaft seals from front and rear case seal bores.

Scheme 9

Legend For (Scheme 9)

1. Input Gear Thrust Washer
2. Input Gear Thrust Bearing
3. Input Gear
4. Mainshaft Pilot Bearing
5. Planetary Assembly
6. Planetary Thrust Washer
7. Annulus Gear
8. Annulus Gear Thrust Washer
9. Needle Bearing Spacers
10. Mainshaft Needle Bearings (120)
11. Needle Bearing Spacer
12. Spacer Washer
13. Oil Pump Gear
14. Speedometer Gear
15. Drive Sprocket Snap Ring
16. Drive Sprocket
17. Blocker Ring
18. Synchronizer Sleeve
19. Synchronizer Spring
20. Synchronizer Key
21. Synchronizer Hub
22. Synchronizer Hub Snap Ring
23. Mainshaft
24. Mainshaft Thrust Bearing
25. Internal Gear Snap Ring
26. Mode Fork
27. Spring
28. Spring Retainer
29. Range Fork Pads
30. Range Fork
31. Range Sector
32. Mode Fork Bracket
33. Rear Case
34. Seal
35. Pump Housing
36. Rear Retainer
37. Bearing Snap Ring
38. Rear Output Bearing
39. Vent Tube
40. Rear Seal
41. Drain & Fill Plugs
42. Front Output Shaft Rear Bearing
43. Front Output Shaft Rear Thrust Bearing Race (Thick)
44. Case Magnet
45. Front Output Shaft Rear Thrust Bearing Race (Thin)
46. Driven Sprocket Retaining Ring
47. Drive Chain
48. Driven Sprocket
49. Front Output Shaft
50. Front Output Shaft Front Thrust Bearing Race (Thin)
51. Front Output Shaft Front Thrust Bearing Race (Thick)
52. Front Output Shaft Front Bearing
53. Front Output Shaft Front Thrust Bearing
54. Operating Lever
55. Washer & Locknut
56. Range Sector Shaft Seal Retainer
57. Range Sector Shaft Seal
58. Detent Ball, Spring & Retainer Bolt
59. Front Seal
60. Front Yoke
61. Yoke Seal Washer
62. Yoke Nut
63. Input Gear Oil Seal
64. Input Gear Front Bearing
65. Front Case
66. Lock Mode Indicator Switch & Washer
67. Input Gear Rear Bearing
68. Lockplate
69. Shifter Fork Shaft
70. Lockplate Bolts
71. Case Alignment Dowels

Scheme 10

Legend For (Scheme 10)

1. Mainshaft
2. Speedometer Drive Gear
3. Rear Housing
4. Bolt
5. Oil Pump Seal
6. Oil Pump Housing
7. Oil Pump Gear
8. Mainshaft Rear Bearing
9. Mainshaft Extension
10. Vent Pipe
11. Mainshaft Extension Bushing
12. Mainshaft Extension Seal
13. Wire Clip
14. Bolt
15. Oil Fill Plug
16. Dowel
17. Washer
18. Bolt
19. Low Range Lock Plate
20. Planetary Gear Carrier
21. Planetary Gear Thrust Washer
22. Annulus Gear
23. Annulus Gear Thrust Washer
24. Range Fork Center Pad
25. Annulus Gear Retainer Ring
26. Synchronizer Retainer Ring
27. Synchronizer
28. Synchronizer Strut Spring
29. Synchronizer Shift Strut
30. Synchronizer Stop Ring
31. Sprocket Roller Spacer
32. Sprocket Roller
33. Sprocket
34. Drive Sprocket Thrust Washer
35. Drive Sprocket Retainer Ring
36. Range Fork
37. Range Fork Shift Pin
38. Mode Fork & Spring Retainer
39. Mode Fork Shifter Spring
40. Mode Fork Spring Cup
41. Shifter Fork Shaft
42. Fork End Play
43. Mode Fork Center Pad
44. Mode Fork
45. Mode Fork Shifter Pin
46. Input Drive Gear Thrust Bearing
47. Input Drive Gear Pilot Bearing
48. Input Drive Gear Plug
49. Input Drive Gear
50. Input Drive Gear Thrust Bearing
51. Input Drive Gear Thrust Washer
52. Range Sector & Shaft
53. Indicator Light Switch
54. Front Housing
55. Bolt
56. Input Drive Gear Seal
57. Input Drive Gear Bushing
58. Range Sector Plunger
59. Poppet Screw Spring
60. Poppet Screw
61. Front Output Yoke Nut
62. Front Output Yoke Seal Washer
63. Front Output Yoke
64. Front Output Yoke Deflector
65. Front Output Shaft Seal
66. Front Output Shaft Bearing
67. Range Sector Shaft Oil Seal
68. Sector & Shaft Retainer
69. Thrust Washer
70. Thrust Bearing
71. Thrust Washer
72. Front Output Shaft
73. Sprocket
74. Driven Sprocket Retaining Ring
75. Drive Chain
76. Front Output Shaft Pilot Bearing
77. Annulus Gear Hub Bushing
78. Dowel Pin
79. Lever
80. Washer
81. Nut

Note. All bearings used in transfer case must be correctly positioned to avoid covering bearing oil feed holes. After replacing any bearing, check bearing position to ensure oil feed is not blocked by bearing.

Scheme 11

Cleaning & Inspection

1. Wash all parts in cleaning solvent. Be sure to remove all traces of gasket from surfaces where used. Apply compressed air to each oil feed port and channel in each case half to wash all parts in cleaning solvent. Be sure to remove all traces of gasket from surfaces where used. Apply compressed air to each oil feed port and channel in each case half to remove any obstruction or residue.
2. Check all gear teeth and splines for burrs, nicks, excessive wear or damage. Inspect all snap rings and thrust washers for excessive wear, distortion or damage.
3. Inspect both case halves for cracks, porosity, damaged mating surfaces, stripped bolt threads or distortion. Check lock plate teeth and hub for cracks, chips or excessive wear.
4. Inspect condition of all bearings in both case halves and input gear. Check condition of bearing bores in both case halves, input gear, rear output shaft, side gear and rear retainer. Replace bearings as required.

Note. During assembly, lubricate all components with Dexron II type oil or petroleum jelly where indicated only. DO NOT use any other type of lubricants.

Reassembly (Ford Motor Co.)

1. Install thrust washer against rear output shaft gear. Install 3 spacer rings inside sprocket carrier gear. Coat inside of sprocket carrier gear and spacer rings with petroleum jelly.
2. Install 2 rows of needle bearings (120 total) inside sprocket carrier. Ensure middle spacer ring is separating rows. Carefully slide sprocket carrier gear over output shaft. Ensure needle bearings do not dislodge. Install spring and sliding clutch on sprocket carrier gear. Install snap ring.
3. Install rear output shaft drive gear on sprocket carrier gear. Install thrust washer, retaining pin and snap ring on rear output shaft. Install sector plate and shift lever. Ensure shift lever is facing 4WD indicator switch and away from case. Apply RTV sealant around locking plate bolt holes.
4. Install locking plate. Install thrust bearing and washer over input shaft side of input gear. Install input shaft through front case. Insert thrust bearing. Install planetary gear assembly so gears and locking plate engage with input gear.
5. Install annulus gear assembly and clutch assembly, with shift fork engaged, over planetary gear assembly hub. Ensure shift fork pin engages shift selector plate slot. Install thrust washer and snap ring. Install shift rail. Ensure large chamfered end is facing rear case.
6. Lightly tap shift rail to seat it. Install oil deflector. Install mode fork, bracket and spring on shift rail. Install rear output shaft assembly in case. Place thin thrust washer, thrust bearing and thick thrust washer on output side of front output shaft.
7. Partially install front output shaft in case. Position drive chain on output shaft driven gear. Place drive chain on rear output shaft drive gear. Slightly raise rear output shaft to install drive chain. Lower assembly ensuring shift fork is engaged with sliding clutch. Install driven gear snap ring.
8. Install thin thrust washer, thrust bearing and thick washer on rear side of front output shaft. Install magnetic (if removed). Apply RTV sealant to rear case mating surface. Install front and rear case together. Install oil pump drive gear on output shaft. Ensure gear notches are facing rear bearing retainer.
9. Install speedometer drive gear. Ensure gear notches are facing rear bearing retainer. Apply petroleum jelly to nylon oil pump housing. Place oil pump housing in rear bearing retainer. Apply RTV sealant to rear bearing retainer mating surface.
10. Install rear bearing retainer so vent fitting is vertical when transfer case is installed. Install oil slinger, yoke, washer and nut on front output shaft. Install rear output yoke. Install detent plunger, spring and plug. Install 4WD indicator switch. Install drain plug. Fill transfer case.

Note. During assembly, lubricate all components with Dexron II type oil or petroleum jelly where indicated only. DO NOT use any other type of lubricants.

Reassembly (All Other Models)

1. Install input gear race and thrust bearing in front case. Install input gear. Install mainshaft thrust bearing in input gear. Install range sector shaft seal and seal retainer. Install range sector.
2. Install operating lever on range sector shaft. Install and tighten shaft washer and lock nut. Install planetary assembly over input gear making sure planetary set is fully seated and meshed with gear. Install planetary thrust washer on planetary hub.
3. If removed, install inserts in range fork. Engage range fork in annulus gear. Install annulus gear over planetary assembly. Install annulus gear thrust washer and retaining snap ring. Align shift rail bores in case and range fork. Install shift rail. NOTE: Ensure shift rail bore is completely dry and contains no oil. Oil may prevent rail from seating completely and also prevent front case installation.
4. Place mainshaft in a soft-jawed vise, with small end down. Coat drive sprocket bore with petroleum jelly. Position bearing retainer at center of carrier bore.
5. Coat needle bearings with petroleum jelly and install 60 needle bearings in each end of drive sprocket bore; a total of 120 bearings are used. Install bearing retainer in each end of sprocket, and position thrust washer on bottom of drive sprocket.
6. Align assembled carrier and needle bearings with mainshaft and install on mainshaft. DO NOT displace needle bearings during installation. Ensure thrust washer is against snap ring. Assemble synchronizer. (Scheme 12)
7. Install synchronizer assembly on mainshaft. Install snap ring. Install front output shaft thrust bearing assembly in front case. Correct sequence is: thick race, thrust bearing, thin race. Install front output shaft.
8. Position sprockets in chain, align sprockets with shafts and install as an assembly. Make sure drive sprocket recessed side is facing into case. Install spacer and thrust washer on drive sprocket. Install snap ring. Install shift rail through mode fork, range fork and case. Install spring and retainer on shift rail.
9. Install driven sprocket retaining snap ring. Install front output shaft rear thrust bearing assembly on front output shaft. Correct sequence is: thin race, thrust bearing, thick race.
10. Install oil pump on mainshaft. Make sure recessed side of pump faces into case. Install speedometer drive gear. Install magnet in front case, if removed. Apply RTV silicone sealant to one side of case and mate rear case on front case.
11. Make sure front output shaft rear thrust bearing assembly is seated in rear case. Align bolt holes and dowels. Install flat washers on 2 bolts installed at opposite ends of case. Install all bolts and tighten.
12. Install rear output bearing in retainer. Install snap ring. Install seal in pump housing. Coat pump housing tabs with petroleum jelly and install housing in rear retainer. Apply sealer to mating surface of rear retainer, align with case index marks, install retainer and bolts.
13. Install oil seal in rear retainer bore. Coat seal lip with petroleum jelly before installation. Install indicator switch and washer. Apply small amount of Loctite 515 to detent retainer bolt and install detent ball, spring and bolt.
14. Install drain plug and gasket. Install oil seal in front case output shaft bore. Install front and rear yokes. Be sure yoke with collar is on front output shaft. Install yoke seal washers and nuts. Fill transfer case and install fill plug.

Scheme 12

COMPONENT DISASSEMBLY & REASSEMBLY

Note. The following is the overhaul of each component, after transfer case has been disassembled. See OVERHAUL section for transfer case disassembly.

Disassembly & Reassembly

Check annulus gear bushing. If replacement is necessary, replace annulus gear.

Remove and discard lock plate attaching bolts. Remove lock plate from case. Coat case and lock plate surfaces around bolt holes with RTV sealant. Position new lock plate in case and align bolt holes in lock plate with case. Coat new lock plate attaching bolts with Loctite. Install and tighten lock plate bolts.

Remove rear seal using screwdriver or brass drift. Remove bearing retaining snap ring. Remove bearing using brass drift. Install new bearing. Ensure that shielded side of bearing faces interior of case. Install bearing retaining snap ring. Install new rear seal.

Remove bearing. Install new front bearing and check bearing position to ensure that oil feed hole is not blocked.

Remove bearing. Install new front bearing and check bearing position to ensure that oil feed hole is not blocked. Ensure that bearing is flush with case.

Remove both bearings at the same time. Install new bearings one at a time. Install rear bearing first; then install front bearing. Remove installer and check bearing position to ensure that oil feed holes are not covered. Ensure that bearings are flush with case.

Remove pilot bearing and plug. Install new bearing and check bearing position to ensure that oil feed hole is not blocked. Ensure that bearing is flush with edge of bearing bore. Install bearing plug.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• LOCK PLATE