GM Astro/Safari 1985-1996 Repair Guide

Driveshaft and U-Joints

Print


WARNING
If the vehicle is to be undercoated, the driveshaft and U-joints must be removed or completely covered to protect them from the undercoating. Failure to do this will most likely result in a loss of balance to the driveshaft leading to vibration and possible early U-joint failure.

REMOVAL & INSTALLATION



Also on the previous section

The driveshaft and its companion flanges are balanced at the factory. They must maintain this original alignment in order to maintain proper balance. Before removing any driveshaft ALWAYS matchmark the shaft to the flanges.

Front
  1. Disconnect the negative battery cable for safety.
  2.  
  3. Raise and support the front of the vehicle safely using jackstands.
  4.  
  5. Matchmark the positions of the driveshaft components relative to the driveshaft and flanges. The components must be reassembled in the same position to maintain proper balance.
  6.  
  7. Remove the transfer case flange and front axle flange-to-driveshaft bolts.
  8.  
  9. Pull the driveshaft forward and down to remove.
  10.  

To install:
  1. Inspect the plastic shrouds (CV-joints) for cracking or deterioration, replace if necessary.
  2.  
  3. Install the shaft, while aligning the reference marks made during removal. The importance of this step cannot be over-emphasized.
  4.  
  5. Install the flange-to-driveshaft bolts at both ends of the shaft.
  6.  
  7. Tighten the transfer case flange bolts to 92 ft. lbs. (125 Nm) for 1990-95 vehicles or to 55 ft. lbs. (75 Nm) for 1996 vehicles.
  8.  
  9. Tighten the front axle flange bolts to 53 ft. lbs. (72 Nm) for 1990-95 vehicles or to 55 ft. lbs. (75 Nm) for 1996 vehicles.
  10.  
  11. Remove the jackstands and carefully lower the vehicle.
  12.  
  13. Connect the negative battery cable and check for proper operation.
  14.  

Rear

See Figures 1, 2, 3 and 4



Click image to see an enlarged view

Fig. Fig. 1: ALWAYS matchmark the driveshaft yoke to the companion flange to assure proper installation



Click image to see an enlarged view

Fig. Fig. 2: Remove the U-joint-to-companion flange retainers, then ...



Click image to see an enlarged view

Fig. Fig. 3: ... push the driveshaft forward slightly and lower the rear from the flange



Click image to see an enlarged view

Fig. Fig. 4: Be sure to tape the U-joint caps to prevent bearing loss or damage should they come loose

  1. Disconnect the negative battery cable for safety.
  2.  
  3. Raise and support the rear of the vehicle safely using jackstands.
  4.  
  5. Using paint, matchmark the relationship of the driveshaft-to-pinion flange. The components must be reassembled in the same position to maintain proper balance.
  6.  
  7. Remove the universal joint-to-rear axle retainers.
  8.  

If the bearing cups are loose, tape them together to prevent dropping or loosing the roller bearings.

  1. Remove the driveshaft by sliding it forward, to disengage it from the axle flange, and then rearward, passing it under the axle housing.
  2.  


WARNING
When removing the driveshaft, DO NOT drop it or allow the universal joints to bend at extreme angles, for this may fracture the plastic injected joints.

  1. Inspect the driveshaft splines and surfaces for burrs, damage or wear.
  2.  

To install:
  1. Position the driveshaft into the transmission, then raise the rear and align it with the matchmarks on the axle flange. The importance of properly aligning the matchmarks made earlier cannot be over-emphasized.
  2.  
  3. Install the universal joint-to-pinion flange bolts and tighten to 27 ft. lbs. (37 Nm).
  4.  
  5. Remove the jackstands and carefully lower the vehicle.
  6.  
  7. Connect the negative battery cable and check for proper operation.
  8.  

U-JOINT OVERHAUL



See Figure 5



Click image to see an enlarged view

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

Two types of universal joints are used: The front of the rear driveshaft uses an internal snapring (production is plastic injected), while the rear driveshaft's rear joint and the double cardan joint used on the rear of the 1995-96 front driveshafts use an external snapring.

KEEP IN MIND that if the U-joints have been replaced, it is possible that one type was substituted for another, since they are often available in the same sizes. To be sure with which type your driveshaft is equipped, visually inspect the trunion bore on the outside of the flange. A snapring should be readily visible if you are using the external snapring type joint. If no snapring is visible, check for a retaining ring at the inner ear of the yoke to make sure there is no internal snapring.

The following procedure requires the use of an Arbor Press, the GM Cross Press tool No. J-9522-3 or equivalent, the GM Spacer tool No. J-9522-5 or equivalent, and a 11/8in. socket.

Internal Snapring (Nylon Injected) Type

See Figures 6, 7, 8, 9, 10 and 11



Click image to see an enlarged view

Fig. Fig. 6: Exploded view of an internal snapring U-joint assembly



Click image to see an enlarged view

Fig. Fig. 7: To remove the U-joint use a cross press and a 11/8 in. (30mm) socket



Click image to see an enlarged view

Fig. Fig. 8: If necessary, the use of a spacer will allow the bearing cup to be pushed further from the yoke



Click image to see an enlarged view

Fig. Fig. 9: A hammer may be used to relieve preload from a snapring (during removal) or to help seat the snapring (during installation)



Click image to see an enlarged view

Fig. Fig. 10: Installing the U-joint bearing cross (spider) to the yoke



Click image to see an enlarged view

Fig. Fig. 11: Installing an internal snapring on a replacement U-joint

  1. While supporting the driveshaft, in the horizontal position, place it so that the lower ear of the front universal joint's shaft yoke is supported on a 1 1 / 8 in. (30mm) socket.
  2.  

DO NOT clamp the driveshaft tube in a vise, for the tube may become damaged.

  1. Using the GM Cross Press tool No. J-9522-3 or equivalent, place it on the horizontal bearing cups and press the lower bearing cup out of the yoke ear; the pressing action will shear the plastic retaining ring from the lower bearing cup. If the bearing cup was not completely removed, insert the GM Spacer tool No. J-9522-5 or equivalent, onto the universal joint, then complete the pressing procedure to remove the joint.
  2.  
  3. Rotate the driveshaft and shear the plastic retainer from the opposite side of the yoke.
  4.  
  5. Disengage the slip yoke from the driveshaft.
  6.  
  7. To remove the universal joint from the slip yoke, perform the procedures used in Steps 1-4.
  8.  

When the front universal joint has been disassembled, it must usually be discarded and replaced with a service kit joint, as the production joint is not usually equipped with bearing retainer grooves on the bearing cups.

  1. Clean (remove any remaining plastic particles), then inspect the slip yoke and driveshaft for damage, wear or burrs.
  2.  

The universal joint service kit includes: A pregreased cross assembly, four bearing cups with seals, needle rollers, washers, four bearing retainers and grease. Make sure that the bearing cup seals are installed to hold the needle bearings in place for handling.

To install:
  1. Position one bearing cup assembly part way into the yoke ear (turn the ear to the bottom), insert the bearing cross (into the yoke) so that the trunnion seats freely into the bearing cup. Turn the yoke 180° and install the other bearing cup assembly.
  2.  

When installing the bearing cup assemblies, make sure the trunnions are started straight and true into the bearing cups.

  1. Using the arbor press, press the bearing cups onto the cross trunnion, until they seat.
  2.  

While installing the bearing cups, twist the cross trunnion to work it into the bearings. If there seems to be a hangup, stop the pressing and recheck the needle roller alignment.

  1. Once the bearing cup retainer grooves have cleared the inside of the yoke, stop the pressing and install the snaprings.
  2.  
  3. If the other bearing cup retainer groove has not cleared the inside of the yoke, use a hammer to aid in the seating procedure.
  4.  
  5. To install the yoke/universal assembly to the driveshaft, perform the Steps 7-10 of this procedure.
  6.  

External Snapring Type

See Figures 12 and 13



Click image to see an enlarged view

Fig. Fig. 12: Exploded view of an external U-joint assembly



Click image to see an enlarged view

Fig. Fig. 13: Exploded view of the double cardan U-joint-1995-96 front driveshaft (AWD vehicles)

  1. Remove the snaprings from inside the yoke ears. This is done by carefully pinching the ends together using a pair of pliers (snapring or needlenose pliers work best).
  2.  

If the ring does not readily snap from the yoke groove, tap the end of the bearing cup lightly to relieve the preload from the snapring.

  1. While supporting the driveshaft, in the horizontal position, position it so that the lower ear of the front universal joint's shaft yoke is supported on a 1 1 / 8 in. (30mm) socket.
  2.  

DO NOT clamp the driveshaft tube in a vise, for the tube may become damaged.

  1. Using the GM Cross Press tool No. J-9522-3 or equivalent, place it on the horizontal bearing cups and press the lower bearing cup out of the yoke ear. If the bearing cup was not completely removed, insert the GM Spacer tool No. J-9522-5 or equivalent, onto the universal joint, then complete the pressing procedure.
  2.  
  3. Rotate the driveshaft (or double cardan joint on late-model front shafts) and press the bearing cup from the opposite side of the yoke.
  4.  
  5. Disengage the slip yoke from the driveshaft (or the cardan joint from the front driveshaft, as applicable).
  6.  
  7. To remove the universal joint from the slip yoke (or to further disassemble the double cardan joint), perform Steps 1-4 which were used to remove the joint from the driveshaft.
  8.  
  9. Clean and inspect the yoke and the driveshaft for damage, wear or burrs.
  10.  

To install:
  1. Position one bearing cup assembly part way into the yoke ear (turn the ear to the bottom), insert the bearing cross (into the yoke) so that the trunnion seats freely into the bearing cup. Turn the yoke 180° and install the other bearing cup assembly.
  2.  

When installing the bearing cup assemblies, make sure the trunnions are started straight and true into the bearing cups.

  1. Using the arbor press, press the bearing cups onto the cross trunnion, until they seat.
  2.  

While installing the bearing cups, twist the cross trunnion to work it into the bearings. If there seems to be a hangup, stop the pressing and recheck the needle roller alignment.

  1. Once the bearing cup clears the retainer grooves (inside of the yoke ear), stop the pressing and install the snaprings.
  2.  
  3. If the other bearing cup has not cleared the retainer groove (inside the yoke ear), use a hammer and a brass drift punch to aid in the seating procedure.
  4.  
  5. To install the yoke (joint)/universal assembly to the driveshaft, perform the Steps 8-11 of this procedure.
  6.  

 
label.common.footer.alt.autozoneLogo