GM Full-Size Trucks 1988-1998 Repair Information

Coil Spring

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CAUTION
Coil springs are under considerable tension. Be very careful when removing and installing them; they can exert enough force to cause serious injury. Always use spring compressors or a safety chain when removing a coil spring or releasing spring tension!

REMOVAL & INSTALLATION



R-Series

See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: Removing the coil spring-R-Series

  1. Raise and support the truck under the frame rails. The control arms should hang freely.
  2.  
  3. Remove the wheel.
  4.  
  5. Disconnect the shock absorber at the lower end and move it aside.
  6.  
  7. Disconnect the stabilizer bar from the lower control arm.
  8.  
  9. Support the lower control arm with a jack and install a spring compressor on the spring, or chain the spring to the control arm as a safety precaution.
  10.  

On trucks with an air cylinder inside the spring, remove the valve core from the cylinder and expel the air by compressing the cylinder with a prybar. With the cylinder compressed, replace the valve core so that the cylinder will stay in the compressed position. Push the cylinder as far as possible towards the top of the spring.

  1. Raise the jack to remove the tension from the lower control arm cross-shaft and remove the two U-bolts securing the cross-shaft to the crossmember.
  2.  


CAUTION
The cross-shaft and lower control arm keeps the coil spring compressed. Use care when you lower the assembly.

  1. Slowly release the jack and lower the control arm until the spring can be removed. Be sure that all compression is relieved from the spring.
  2.  
  3. If the spring was chained, remove the chain and spring. If you used spring compressors, remove the spring and slowly release the compressors.
  4.  
  5. Remove the air cylinder, if so equipped.
  6.  

To install:

Installation is the reverse of removal but please note the following important steps.

  1. Install the air cylinder so that the protector plate is towards the upper control arm. The schrader valve should protrude through the hole in the lower control arm.
  2.  
  3. Tighten the two U-bolts securing the cross-shaft to the crossmember to 85 ft. lbs. (115 Nm).
  4.  
  5. Tighten the stabilizer bar-to-lower control arm nuts to 24 ft. lbs. (32 Nm).
  6.  
  7. Tighten the shock absorber bolt to 59 ft. lbs. (80 Nm).
  8.  
  9. If equipped with air cylinders, inflate the cylinder to 60 psi (413 kPa).
  10.  
  11. Lower the truck. Once the weight of the truck is on the wheels, reduce the air cylinder pressure to 50 psi (344 kPa). Have the alignment checked.
  12.  

C-Series

See Figures 2 and 3

  1. Raise and support the truck under the frame rails. The control arms should hang freely.
  2.  
  3. Remove the wheel.
  4.  
  5. Remove the shock absorber.
  6.  
  7. Disconnect the stabilizer bar from the lower control arm.
  8.  
  9. Support the lower control arm and install a spring compressor on the spring, or chain the spring to the control arm as a safety precaution.
  10.  



Click image to see an enlarged view

Fig. Fig. 2: Cradling the lower control arm-C-Series



Click image to see an enlarged view

Fig. Fig. 3: Coil spring positioning-C-Series

  1. Raise the jack to remove the tension from the lower control arm pivot bolts. Remove the rear, then the front pivot bolts.
  2.  


CAUTION
The lower control arm keeps the coil spring compressed. Use care when you lower the assembly.

  1. Slowly release the jack and lower the control arm until the spring can be removed. Be sure that all compression is relieved from the spring.
  2.  
  3. Place a piece of tape on one of the lower coil so you can tell the top from the bottom during installation. If the spring was chained, remove the chain and spring. If you used spring compressors, remove the spring and slowly release the compressors.
  4.  

To install:

Installation is the reverse of removal but please note the following important steps.

  1. Install the chain and spring. If you used spring compressors, install the spring and compressors.

    Make sure that the insulator is in place.
     
    Make sure that the tape is at the lower end. New springs will have an identifying tape.
     
    Make sure that the gripper notch on the top coil is in the frame bracket.
     
    Make sure that on drain hole in the lower arm is covered by the bottom coil and the other is open.
     

  2.  
  3. Install the pivot shaft bolts, front one first. The bolts must be installed with the heads towards the front of the truck! Remove the safety chain or spring compressors.
  4.  

Do not tighten the bolts while the vehicle is raised. The bolts must be torqued with the truck at its proper ride height.

  1. Lower the truck. Once the weight of the truck is on the wheels:
    1. Lift the front bumper about 38mm and let it drop.
    2.  
    3. Repeat this procedure 2 or 3 more times.
    4.  
    5. Draw a line on the side of the lower control arm from the centerline of the control arm pivot shaft, dead level to the outer end of the control arm.
    6.  
    7. Measure the distance between the lowest corner of the steering knuckle and the line on the control arm. Record the figure.
    8.  
    9. Push down about 38mm on the front bumper and let it return. Repeat the procedure 2 or 3 more times.
    10.  
    11. Re-measure the distance at the control arm.
    12.  
    13. Determine the average of the 2 measurements. The average distance should be 95.0mm plus or minus 6mm.
    14.  
    15. If the figure is correct, tighten the control arm pivot nuts to 96 ft. lbs. (130 Nm) on 1988-90 models; 121 ft. lbs. (165 Nm) on 1991-95 models and 101 ft. lbs. (137 Nm) on 1996-98 models.
    16.  
    17. If the figure is not correct, tighten the bolts to specification and have the front end alignment corrected.
    18.  

  2.  

 
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