ISUZU Amigo/Pick-ups/Rodeo/Trooper 1981-1996

Front Driveshaft and U-Joints

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GENERAL DESCRIPTION



Torque is transmitted from the transmission to the rear axle through the driveshaft and Universal joint (U-joint) assemblies.

All driveshafts are the balanced tubular type. A splined slip-joint is provided in some drivelines.

The driveshaft is designed and built with the yoke lugs (ears) in line with each other. This design produces the smoothest running shaft possible, called phasing.

Vibration can be caused by an out-of-phase driveshaft. The propeller shaft will absorb vibrations from speeding up and slowing down each time the U-joint revolves. This vibration would be the same as a person snapping a rope and watching the wave'' reaction flow to the end of the rope. A driveshaft working in phase would be similar to 2 people snapping the same rope at the same time, and watching the waves'' meet and cancel each other out. In comparison, this would be the same as the U-joints on the driveshaft. A total cancellation of vibration produces a smooth flow of power in the driveline. It is very important to apply a reference mark (matchmark) to the driveshaft before removal, to assure installation alignment.

A Universal joint (U-joint) consists of 2 Y-shaped yokes connected by a crossmember called a spider. The spider is shaped like a cross.

Universal joints are designed to handle the effects of various loads and front or rear axle wind-up during acceleration. Within the designed angle variations, the U-joint will operate efficiently and safely. When the design angle is changed or exceeded the operational life of the joint may decrease. The bearings used in U-joints are of the needle roller type. The needle rollers are held in place on the trunnions by round bearing cups. The bearing cups are held in the yokes by snaprings.

REMOVAL & INSTALLATION



See Figures 1 and 2



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Fig. Fig. 1: Cut-away views of 3 common front driveshafts found on Isuzu trucks and Sport Utility vehicles



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Fig. Fig. 2: Exploded view of a common front driveshaft and mounting fasteners

Except 1995-96 Trooper and Rodeo
  1. Apply the parking brake and block the rear wheels.
  2.  
  3. Raise and safely support the front of the vehicle on jackstands.
  4.  
  5. Matchmark the driveshaft flange-to-transfer case flange and the driveshaft-to-differential pinion flange for reassembly.
  6.  
  7. Matchmark the front and rear parts of the driveshaft so they can be reassembled in the same position.
  8.  
  9. Remove the front driveshaft's splined yoke flange-to-transfer case bolts and separate the front driveshaft from the transfer case. Do not allow the splined flange to fall away from the transfer case; lower the driveshaft carefully.
  10.  
  11. Remove the driveshaft flange-to-differential pinion flange bolts and separate the driveshaft from the front differential.
  12.  

To install:
  1. Align the matchmarks and install the driveshaft to the differential unit and the transfer case.
  2.  
  3. Install the driveshaft flange-to-differential pinion flange bolts. Tighten the bolts to 46 ft. lbs. (63 Nm).
  4.  
  5. Connect the driveshaft flange to the transfer case yoke and install the front driveshaft's splined yoke flange-to-transfer case bolts. Tighten the bolts to 46 ft. lbs. (63 Nm).
  6.  
  7. Lower the vehicle and remove the rear wheel blocks.
  8.  

1995-96 Trooper and Rodeo
  1. Shift the transmission into N , and the transfer case into 2H . Make sure the front axle and hubs are disengaged.
  2.  
  3. Apply the parking brake and block the rear wheels.
  4.  
  5. Raise and safely support the front of the vehicle on jackstands.
  6.  
  7. Remove the transmission and transfer case skid plates.
  8.  
  9. Matchmark the driveshaft flanges to the transfer case flange and differential pinion flange.
  10.  
  11. Matchmark the front and rear parts of the driveshaft so they can be reassembled in the same position, if the sliding yoke is going to be separated from the rear part of the driveshaft.
  12.  
  13. Remove the bolts attaching the front driveshaft flange to the transfer case flange and separate the front driveshaft from the transfer case.
  14.  
  15. Remove the bolts attaching the driveshaft flange to the differential pinion flange and separate the driveshaft from the front differential.
  16.  
  17. Remove the driveshaft from the vehicle.
  18.  
  19. Clean the flange mounting surfaces to remove any rust or dirt.
  20.  

To install:
  1. Align the matchmarks and install the driveshaft.
  2.  
  3. Install the bolts attaching the driveshaft flange to the differential pinion flange. Tighten the bolts to 46 ft. lbs. (63 Nm).
  4.  
  5. Connect the driveshaft flange to the transfer case flange and install the attaching bolts. Tighten the bolts to 46 ft. lbs. (63 Nm).
  6.  
  7. Repaint the exposed portions of the flanges so they do not rust.
  8.  
  9. Install the transfer case and transmission skid plates and tighten their bolts to 27 ft. lbs. (37 Nm).
  10.  
  11. Lower the vehicle and remove the rear wheel blocks.
  12.  

U-JOINT REPLACEMENT



See Figures 3, 4 and 5



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Fig. Fig. 3: Exploded view of the U-joint, which is the same for all models covered by this guide



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Fig. Fig. 4: Apply a molybdenum-disulfide grease or a multipurpose type grease NLG1 No. 2 to the bearing cap inner surface, then install the needle rollers



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Fig. Fig. 5: Install the oil seal so its outer lip is flush with the outer edge of the bearing cap

  1. Raise and support the vehicle safely. Remove the driveshaft.
  2.  
  3. If the front yoke is to be disassembled, matchmark the driveshaft and sliding splined yoke so driveline balance is preserved upon reassembly. Remove the snaprings that retain the bearing caps on the U-joint.
  4.  
  5. Select 2 press components, with one being small enough to pass through the yoke holes for the bearing caps and the other being large enough to receive the bearing cap.
  6.  
  7. Use a vise or a press and position the small and large press components on either side of the U-joint. Press in on the smaller press component so it presses the opposite bearing cap out of the yoke and into the larger press component. If the cap does not come all of the way out, grasp it with a pair of pliers and work it out.
  8.  
  9. Reverse the position of the press components so the smaller press component presses on the U-joint spider (cross-shaped center piece). Press the opposite bearing cap out of the yoke.
  10.  
  11. Repeat the procedure on the other bearings.
  12.  
  13. If equipped, remove the old seals from the bearing caps. Discard the old seals.
  14.  
  15. Remove the U-joint cross piece from the U-joint retaining bracket.
  16.  

To install:
  1. Grease the bearing caps and needles thoroughly with a molybdenum-disulfide grease or a multipurpose type grease NLG1 No. 2, if they are not pregreased. Install a new oil seal into each bearing cap so its outer surface is flush with the bearing cap surface.
  2.  
  3. Start a new bearing cap into a side of the yoke, then position the spider in the yoke.
  4.  

Some U-joints have a grease fitting that must be installed in the joint before assembly. When installing the fitting, make sure once the driveshaft is installed in the vehicle that the fitting is accessible to be greased at a later date.

  1. Select 2 press components small enough to pass through the yoke holes. Put the press components against the cross and the cap and press the bearing cap 1 / 4 in. (6mm) below the surface of the yoke. If there is a sudden increase in the force needed to press the cap into place, or if the cross starts to bind, the bearings are cocked. They must be removed and restarted in the yoke. Failure to do so will cause premature bearing failure.
  2.  
  3. Install a new snapring.
  4.  
  5. Start the new bearing into the opposite side. Place a press component on it and press in until the opposite bearing contacts the snapring.
  6.  
  7. Install a new snapring. It may be necessary to grind the facing surface of the snapring slightly to permit easier installation.
  8.  
  9. Install the other bearings in the same manner.
  10.  
  11. Check the joint for free movement. If binding exists, smack the yoke ears with a brass or plastic faced hammer to seat the bearing needles. If binding still exists, disassemble the joint and check to see if the needles are in place. Do not strike the bearings unless the shaft is supported firmly. Do not install the driveshaft until free movement exists at all joints.
  12.  
  13. Install the driveshafts into the vehicle.
  14.  
  15. Lower the vehicle.
  16.  
  17. Test drive the vehicle and check for driveline vibrations.
  18.  

 
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