GM Full Size Vans 1987-1997 Repair Guide

Driveshaft and U-Joints

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REMOVAL & INSTALLATION



See Figures 1 through 4



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Fig. Fig. 1: Unfasten the driveshaft retaining bolts



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Fig. Fig. 2: Remove the driveshaft retaining straps

  1. Raise the vehicle and support it on jackstands. There is less chance of lubricant leakage from the rear of the transmission if the rear is raised.
  2.  
  3. Matchmark the driveshaft and rear pinion flange and if equipped both halves of the 2-piece driveshaft.
  4.  
  5. Remove the U-bolts or straps at the rear axle. Tape the bearing cups to the trunnions.
  6.  
  7. On models with a 2-piece driveshaft, remove the bolts attaching the bearing support to the frame crossmember.
  8.  
  9. Slide the driveshaft forward and lower it. Slide the driveshaft toward the rear of the vehicle and disengage the splined sleeve from the output shaft of the transmission.
  10.  
  11. Remove the driveshaft from under the van.
  12.  



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Fig. Fig. 3: Tape the bearings into place to avoid losing them



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Fig. Fig. 4: Lower the rear end of the shaft, then pull it back out of the transmission:

To install:
  1. Installation is the reverse of removal. Use the matchmarks made previously to help facilitate alignment. For models with 2-piece driveshaft, install the front half into the transmission and install the support to the crossmember. Rotate the shaft so that the front U-joint trunnions so that all are vertical. Rotate the rear shaft 4 splines to the left of the vehicle and connect the front and rear shaft. Some 2-piece driveshafts can only be assembled one way, in which case these instructions can be ignored. Attach the rear U-joint to the axle. On automatic transmission models, lubricate the internal yoke splines at the transmission end of the shaft with lithium base grease. The grease should seep out through the vent hole.
  2.  

A thump in the rear driveshaft sometimes occurs when releasing the brakes after braking to a stop, especially on a downgrade. This is most common with automatic transmission. It is often caused by the driveshaft splines binding and can be cured by removing the driveshaft, inspecting the splines for rough spots or sharp edges, and carefully lubricating.

OVERHAUL



There are two types of U-joints used in these vans. The first is held together by wire snaprings in the yokes. The second type is held together with injection molded plastic retainer rings. This type cannot be reassembled with the same parts, once disassembled. However, repair kits are available.

Snapring Type

See Figures 5, 6, 7, 8 and 9



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Fig. Fig. 5: An external snapring type U-joint is easily identified by the visible snapring in the yoke bore

  1. Remove the driveshaft from the van.
  2.  
  3. Remove the lockrings from the yoke and remove the lubrication fitting.
  4.  
  5. Support the yoke in a bench vise. Never clamp the driveshaft tube.
  6.  
  7. Use a soft drift pin and hammer to drive against one trunnion bearing to drive the opposite bearing from the yoke.
  8.  

The bearing cap cannot be driven completely out.

  1. Grasp the cap and work it out.
  2.  
  3. Support the other side of the yoke and drive the other bearing cap from the yoke and remove as in Steps 4 and 5.
  4.  
  5. Remove the trunnion from the driveshaft yoke.
  6.  
  7. If equipped with a sliding sleeve, remove the trunnions bearings from the sleeve yoke in the same manner as above. Remove the seal retainer from the end of the sleeve and pull the seal and washer from the retainer.
  8.  

To remove the bearing support:
  1. Remove the dust shield, or, if equipped with a flange, remove the cotter pin and nut and pull the flange and deflector assembly from the shaft.
  2.  
  3. Remove the support bracket from the rubber cushion and pull the cushion away from the bearing.
  4.  
  5. Pull the bearing assembly from the shaft. If equipped, remove the grease retainers and slingers from the bearing.
  6.  

Assemble the bearing support as follows:
  1. Install the inner deflector on the driveshaft and punch the deflector on 2 opposite sides to be sure that it is tight.
  2.  
  3. Pack the retainers with special high melting grease. Insert a slinger (if used) inside one retainer and press this retainer over the bearing outer race.
  4.  
  5. Start the bearing and slinger on the shaft journal. Support the driveshaft and press the bearing and inner slinger against the shoulder of the shaft with a suitable pipe.
  6.  
  7. Install the second slinger on the shaft and press the second retainer on the shaft.
  8.  
  9. Install the dust shield over the shaft (small diameter first) and depress it into position against the outer slinger or, if equipped with a flange, install the flange and deflector. Align the centerline of the flange yoke with the centerline of the driveshaft yoke and start the flange straight on the splines of the shaft with the end of the flange against the slinger.
  10.  
  11. Force the rubber cushion onto the bearing and coat the outside diameter of the cushion with clean brake fluid.
  12.  
  13. Force the bracket onto the cushion.
  14.  

Assemble the trunnion bearings:
  1. Repack the bearings with grease and replace the trunnion dust seals after any operation that requires disassembly of the U-joint. But be sure that the lubricant reservoir at the end of the trunnion is full of lubricant. Fill the reservoirs with lubricant from the bottom.
  2.  
  3. Install the trunnion into the driveshaft yoke and press the bearings into the yoke over the trunnion hubs as far as it will go.
  4.  
  5. Install the lockrings.
  6.  
  7. Hold the trunnion in one hand and tap the yoke slightly to seat the bearings against the lockrings.
  8.  
  9. On the rear driveshafts, install the sleeve yoke over the trunnion hubs and install the bearings in the same manner as above.
  10.  



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Fig. Fig. 6: Installing the retaining ring - snapring-type



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Fig. Fig. 7: Seating the U-joint snapring



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Fig. Fig. 8: Exploded view of the internal snapring U-joint



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Fig. Fig. 9: Exploded view of the external snapring U-joint

Molded Retainer Type

See Figures 10, 11, 12 and 13

  1. Remove the driveshaft.
  2.  
  3. Support the driveshaft in a horizontal position. Place the U-joint so that the lower ear of the shaft yoke is supported by a 1 1 / 8 in. socket. Press the lower bearing cup out of the yoke ear. This will shear the plastic retaining the lower bearing cup.
  4.  

Never clamp the driveshaft tubing in a vise.

  1. If the bearing cup is not completely removed, lift the cross, insert a spacer and press the cup completely out.
  2.  
  3. Rotate the driveshaft, shear the opposite plastic retainer, and press the other bearing cup out in the same manner.
  4.  
  5. Remove the cross from the yoke. Production U-joints cannot be reassembled. There are no bearing retainer grooves in the cups. Discard all parts that we removed and substitute those in the overhaul kit.
  6.  
  7. Remove the sheared plastic bearing retainer. Drive a small pin or punch through the injection holes to aid in removal.
  8.  
  9. If the front U-joint is serviced, remove the bearing cups from the slip yoke in the manner previously described.
  10.  
  11. Be sure that the seals are installed on the service bearing cups to hold the needle bearings in place for handling. Grease the bearings if they aren't pregreased.
  12.  
  13. Install one bearing cup partway into one side of the yoke and turn this ear to the bottom.
  14.  
  15. Insert the opposite bearing cup partway. Be sure that both trunnions are started straight into the bearing cups.
  16.  
  17. Press against opposite bearing cups, working the cross constantly to be sure that it is free in the cups. If binding occurs, check the needle rollers to be sure that one needle has not become lodged under an end of the trunnion.
  18.  
  19. As soon as one bearing retainer groove is exposed, stop pressing and install the bearing retainer snapring.
  20.  
  21. Continue to press until the opposite bearing retainer can be installed. If difficulty installing the snaprings is encountered, tap the yoke with a hammer to spring the yoke ears slightly.
  22.  
  23. Assemble the other half of the U-joint in the same manner.
  24.  



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Fig. Fig. 10: Pressing out the U-joint



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Fig. Fig. 11: Using the spacer - molded-type



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Fig. Fig. 12: Partially inserted bearing cup



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Fig. Fig. 13: Align the trunnion between the bearing cups

DRIVESHAFT BALANCING



  1. Raise the vehicle and support it with jackstands.
  2.  
  3. Remove the wheel, tire assemblies and brake drums or rotors.
  4.  
  5. Inspact the driveshaft for dirt, loose retainers, dame and defective U-joints.
  6.  
  7. Clean the driveshaft and U-joints and tighten any loose retainers.
  8.  
  9. Run the vehicle in gear at the same speed that the problem occurs.
  10.  
  11. If the problem does repeats, shut off the engine and remove the driveshaft as outlined in this section.
  12.  
  13. Rotate the driveshaft 180 degrees from its original position.
  14.  
  15. Install the driveshaft and repeat Step 5. If the problem occurs again repeat Step 6.
  16.  
  17. Keep performing Steps 5 and 6 until a position is reached that gives the best balance.
  18.  
  19. Install the rotors or drums and the wheel and tire assemblies.
  20.  
  21. Lower the vehicle and check for proper operation.
  22.  

 
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