Isuzu Cars and Trucks 1981-1991

5-Speed Overhaul Late Model Trooper, Amigo and Rodeo

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BEFORE DISASSEMBLY

Cleanliness is an important factor in the overhaul of the manual transmission. Before opening up this unit, the entire outside of the transmission assembly should be cleaned, preferably with a high pressure washer such as a car wash spray unit. Dirt entering the transmission internal parts will negate all the time and effort spent on the overhaul. During inspection and reassembly all parts should be thoroughly cleaned with solvent then dried with compressed air. Wiping cloths and rags should not be used to dry parts.

Wheel bearing grease, used to hold thrust washers and lube parts, should not be used. Lube seals with clean SAE 30 weight engine oil and use ordinary unmedicated petroleum jelly to hold the thrust washers, needle bearings and to ease the assembly of seals, since it will not leave a harmful residue as grease often will.

Before installing bolts into aluminum parts, always dip the threads into clean transmission fluid. Anti-seize compound can also be used to prevent bolts from galling the aluminum and seizing. Always use a torque wrench to keep from stripping the threads. Take care when installing new O-rings, especially the smaller O-rings. The internal snaprings should be expanded and the external rings should be compressed, if they are to be reused. This will help insure proper seating when installed.

TRANSMISSION DISASSEMBLY
  1. Position the transmission is a suitable holding fixture.
  2.  
  3. Drain the lubricant, as required.
  4.  
  5. Remove the speedometer driven gear and transfer flange using a flange remover J37221 or equivalent.
  6.  
  7. Remove the front cover with oil seal, countershaft snapring and top gear shaft snapring.
  8.  
  9. Remove the transmission-to-transfer case bolts and separate the assemblies.
  10.  



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Fig. Major components disassembly late P'up, Trooper, Amigo and Rodeo



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Fig. Transmission disassembly late P'up, Trooper, Amigo and Rodeo

UNIT DISASSEMBLY AND ASSEMBLY
Intermediate Plate and Shift Arms
DISASSEMBLY
  1. Remove the detent spring plate, springs and balls using a pencil magnet.
  2.  
  3. Remove the spring, 5th/rev shift rod, 5th/rev shift arm and inhibitor by driving out the spring pin.
  4.  
  5. Remove the 1st/2nd shift rod, 3rd/4th shift rod, 3rd/4th shift arm and 1st/2nd shift arm.
  6.  


NOTE
Place a round bar under the shift rods before removing spring pins.

  1. Remove the interlock pins from the 3rd/4th shift rod.
  2.  



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Fig. Intermediate plate and shift arm assemblies late P'up, Trooper, Amigo and Rodeo

ASSEMBLY
  1. Onto the intermediate plate and gear assemblies, install the 1st/2nd shift arm, 3rd/4th shift arm, 3rd/4th shift rod, interlock pins and 1st/2nd shift rod. Drive in the spring pins to hold in place.
  2.  
  3. Install the 5th/rev shift arm and inhibitor, 5th/rev shift rod and spring.
  4.  
  5. Install the detent balls, springs and plate. Torque the plate bolts to 11 ft. lbs. (15 Nm).
  6.  

Reverse and 5th Gear
DISASSEMBLY
  1. Remove the oil seal collar and pull the bearing off with retainer remover tool J37222 or equivalent and a puller.
  2.  
  3. Remove the thrust plate, thrust washer and lock ball.
  4.  
  5. Remove the idler gear snapring, 5th counter gear snapring and pull off the 5th counter gear and bearing using a puller.
  6.  
  7. Remove the reverse idler shaft, reverse idler gear, thrust washer and idle shaft pin.
  8.  
  9. Remove the reverse counter gear, 5th blocker ring and needle bearings.
  10.  
  11. Engage the 3rd/4th synchronizer with the 3rd gear, engage the 1st/2nd synchronizer with the 1st gear and remove the clutch hub nut using a hub wrench J37219.
  12.  
  13. Remove the 5th/rev synchronizer assembly by prying upwards with a pair of prybars.
  14.  
  15. Remove the reverse ring, reverse gear and needle bearing.
  16.  
  17. Using a Torxand#x00AE; bit wrench J37225, remove the bearing plate screws and plate.
  18.  
  19. Remove the bearing snapring and intermediate plate.
  20.  



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Fig. 5th counter gear removal late P'up, Trooper, Amigo and Rodeo



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Fig. Reverse and 5th gear assembly late P'up, Trooper, Amigo and Rodeo

ASSEMBLY
  1. Mesh the counter gear with the mainshaft, install the holding fixture J37224 or equivalent to the assembly and install the intermediate plate.
  2.  
  3. Apply thread locking compound to the bearing plate screws and torque to 11 ft. lbs. (15 Nm).
  4.  
  5. Install the 5th/rev synchronizer assembly, clutch hub nut, torque to 94 ft. lbs. (128 Nm) and stake the nut with a punch.
  6.  
  7. Install the needle bearings, 5th blocker ring and 5th gear.
  8.  
  9. Install the reverse counter gear with the projection facing the intermediate plate. Install the idler shaft pin, thrust washer, reverse idler gear, 5th counter gear and idler shaft, using a plastic hammer to drive in place.
  10.  
  11. Install the idler shaft bearing and selective snapring that meets the clearance of 00.0059 in. (00.15mm).
  12.  
  13. Install the reverse gear snapring.
  14.  
  15. Install the thrust washer and lock ball, thrust plate, retainer, bearing and oil seal collar.
  16.  



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Fig. Rev/5th synchronizer assembly 1. clutch hub, 2. small groove, 3. inserts, 4. springs, 5. clutch hub, 6. sleeve



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Fig. Clutch hub and reverse counter gear installation late P'up, Trooper, Amigo and Rodeo

Mainshaft, Counter and Top Gear Shafts
DISASSEMBLY
  1. Remove the top shaft snapring, top gear shaft, needle bearings and press off the bearing.
  2.  
  3. Remove the top blocker ring, mainshaft snapring and 3rd/4th synchronizer assembly.
  4.  
  5. Remove the 3rd blocker ring, 3rd gear, needle bearings and press off the needle bearing collar.
  6.  
  7. Press off the mainshaft bearing, the thrust bearing and 1st gear.
  8.  
  9. Remove the 1st blocker ring, needle bearings and clutch hub snapring.
  10.  
  11. Remove the 1st/2nd synchronizer assembly, 2nd blocker ring, 2nd gear and needle bearings. A press may be needed.
  12.  
  13. From the counter gear, remove the bearing snapring and both bearings with a press.
  14.  



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Fig. Mainshaft, counter gear and top gear late P'up, Trooper, Amigo and Rodeo

ASSEMBLY
  1. Onto the mainshaft, install the needle bearings and 2nd gear so the dog teeth are facing rearward.
  2.  
  3. Install the 2nd blocker ring and 1st/2nd synchronizer assembly. Turn the shallow clutch hub face toward the side of the sleeve with the small groove on the outer circumference. Check to see if the sleeve slides smoothly.
  4.  
  5. Install the clutch hub selective snapring, needle bearings, 1st blocker ring, 1st gear and 1st gear thrust bearing. Thrust bearing face must face forward.
  6.  
  7. Press on the mainshaft bearing and bearing collar.
  8.  
  9. Install the 3rd gear needle bearings, 3rd gear, 3rd blocker ring and 3rd/4th synchronizer assembly. The 3rd gear dog teeth must face forward. Turn the synchronizer clutch hub face with the heavy boss toward the side of the sleeve with the small groove on the outer circumference. Make sure the sleeve slides smoothly.
  10.  
  11. Install the mainshaft selective snapring, needle bearings, top blocker ring, and top gear shaft.
  12.  
  13. Press on top shaft bearing and install snapring.
  14.  
  15. Onto the counter gear, press on the front and rear bearings and install the snapring.
  16.  



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Fig. 2nd gear positioning



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Fig. Low/2nd synchronizer assembly



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Fig. Mainshaft, cluster gear and top gear assembly



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Fig. Synchronizer assembly 1. key, 2. spring, 3. clutch



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Fig. Top/3rd synchronizer assembly



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Fig. Low/rev trust washer oil groove position

Inspection
  1. Using a micrometer, check the shift arm thickness where it rides on the synchronizer. 1st/2nd = 0.354 and 190.388 in. (9.0 and 199.8mm), 3rd/4th = 0.354 and 190.386 in. (9.0 and 199.9mm), transfer = 0.354 and 190.388 in. (9.0 and 199.8mm) and 5th/reverse = 0.354 and 190.386 in. (9.0 and 199.9mm).
  2.  
  3. Using a inside slide ruler, check the free length of the detent springs. All springs (except transfer) 1.03 and 191.06 in. (26.2 and 1926.8mm) and transfer interlock = 0.603 and 190.626 in. (1.53 and 191.59).
  4.  
  5. Using a spring tension tester, check the detent spring tension. 1st/2nd, 3rd/4th and 5th/rev = 20.0 and 1922.0 lbs. (8.9 and 199.9 kg), transfer = 15.0 and 1917.0 lbs. (6.6 and 197.6 kg) and transfer interlock = 2.2 lbs. (1.0 kg).
  6.  
  7. Using a feeler gauge, check the clearance between the blocker ring and dog teeth. Standard clearance 0.032 and 190.059 in. (0.8 and 191.5mm).
  8.  
  9. Using a feeler gauge, check the clearance between the blocker rings and inserts. Standard clearance for 3rd/4th = 0.138 and 190.158 in. (3.51 and 194.00mm), 1st/2nd andamp; transfer = 0.171 and 190.193 in. (4.34 and 195.00mm) and 5th = 0.141 and 190.161 in. (3.59 and 194.10mm).
  10.  
  11. Using a feeler gauge, check the clearance between the clutch hub and inserts. Standard clearance 0.0004 and 190.012 in. (0.01 and 190.3mm).
  12.  
  13. Using a dial indicator and holding fixture, check the mainshaft run-out. Limit 0.0019 in. (0.05mm).
  14.  
  15. Using an inside T-gauge, check the gear inside diameter. 1st-3rd = 1.773 and 191.777 in. (45.0 and 1945.1mm), 2nd gear = 2.047 and 192.051 in. (52.0 and 1952.1mm), transfer/rev = 1.893 and 191.900 in. (48.0 and 1948.1mm) and 5th = 1.246 and 191.260 in. (32.0 and 1932.1mm).
  16.  
  17. Using a micrometer, check the clearance between the bushing and idler gear shaft. Standard clearance 0.0016 and 190.0059 in. (0.041 and 190.150mm).
  18.  
  19. Using a dial indicator, check the spline play. Clutch hub 0.0 and 190.0079 in. (0.0 and 190.20mm) and reverse gear 0.0 and 190.0120 in. (0.0 and 190.3mm).
  20.  
  21. Using a dial indicator, check the play in the ball bearings. Limit 0.068 in. (0.2mm).
  22.  
  23. Replace components that do not meet specifications.
  24.  



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Fig. Shift arm thickness check



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Fig. Detent spring check



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Fig. Blocker ring to gear clearance check

ASSEMBLY
  1. Apply liquid sealer to the transfer rear case fitting surfaces.
  2.  
  3. Shift the high/low synchronizer to the 4H side. Turn the select rod counterclockwise so that the select block projection may enter into the 4x2/4x4 shift block.
  4.  
  5. Install the gear shafts and intermediate plate into the main and transfer housing. The cut away portion the select rod head should align with the rear case hole stopper in the transfer housing.
  6.  
  7. Install the transfer case-to-transmission bolts and torque to 28 ft. lbs. (37 Nm).
  8.  
  9. Install the front countershaft and top shaft bearing snaprings.
  10.  
  11. Apply liquid gasket to the front cover and install a new seal with a seal installer tool J26540. Install the cover and torque the bolts to 14 ft. lbs. (19 Nm).
  12.  
  13. Using a flange holder J27221, install the transfer flange to the rear transfer case and speedometer driven gear.
  14.  

 
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