1973-1991 K20 4x4 Radius Arm Conversion Installation Instructions 1- Radius arm Hangers 2- Bracket, Driver Lower 3- Bracket, Passenger Upper 4- Radius Arm
5- Bracket, Driver Upper 6- Bracket, Passenger Lower 7- Clamp, Passenger Lower bag mount 8- Pitman Drag Link Bar 9- Tierod Bar 10- Front Trac Bar Congratulations! You have just purchased the best engineered, highest quality front air suspension kit available on the market for your 73-91 K20 4x4 pickup. When installed, this kit will allow complete control and adjustability over your truck s suspension. Be sure to fully read and
understand the instructions before starting your installation. As in any suspension installation, it is the installer s responsibility to assure a correct installation. The installer is also responsible for providing adequate clearances between vehicle components such as axles, shocks, exhaust and mechanical linkages to ensure a safe and reliable installation. WARNING DO NOT EXCEED THE MANUFACTURER S RECOMMENDED GROSS VEHICLE WEIGHT RATING (GVWR). 1. Raise the vehicle until wheels are off the ground and support with jack stands under the frame. 2. Support the front axle with jack stands and remove the wheels. Extreme caution should be used in the next few steps to prevent personal injury and/or property damage. Make sure springs are unloaded before attempting to remove them. Failure to do so can cause the spring to eject. Use a floor jack to find the neutral position of the springs before removal. 3. Remove the leaf springs and the shackle assembly 4. Remove the factory panhard bar 5. Remove the original upper shock towers 6. Remove the rivets that attach the factory leaf spring hanger to the frame 7. Install the new radius arm mounts on the frame under the cab. They mount behind the front cab mounts.2 holes on the side of the mount line up with existing holes in the frame from the leaf spring hanger. Drill the 3 remaining holes through the frame and tighten the bolts securing the bracket. NOTE: Depending on your engine and transmission combination, the transmission cross member may need to be removed to drill and install the radius arm brackets. The cross member can then be reinstalled without modification over the new mounts. The picture below is actually a Chevrolet C1500, but your procedure is the same.
8. Install the upper and lower halves of the axle radius arm mounts on the driver s side ale tube. The lower half will fit snugly against the axle and the upper half will locate in the centering pin of the leaf spring pad. Install 9/16-11 x 7 bolts finger tight for now. 9. The passenger side axle radius arm mounts are slightly different than the driver s side. The upper mount still has a centering pin to mount in the leaf spring pad, but it also has a track bar mount and and will clamp to the axle housing. Line up the lower mount with the factory leaf spring pad and finger tighten the bolts for now, using 4 9/16 x 3 and short U-Bolt 10. Track Bar mounts on the axle bracket. There is a slight bend in the frame underneath the steering box that the bracket will fit snugly against. The bracket will also contact the engine cross member. Clamp the track bar bracket in place and drill the 3 mounting holes and install and tighten the mounting bolts. Picture below is C1500
11. Install the track bar with the bushing end mounted to the frame side bracket and the heim joint on the axle end. (It may be necessary to break the passenger side tie rod loose from the knuckle to get the heim joint s mounting bolt installed) 12. Install the radius arm in the axle mounts with the shock mount facing the top of the truck.. 13. After the radius arms are installed in the axle brackets the mounting bolts that were left finger tight in steps 8 and 9 can now be tightened 14. Mount the upper bag mount/shock mount to the frame with the shock mount facing the rear of the truck. Some of the mounting holes may line up with existing holes on the frame, the others will need to be drilled 15. Use the supplied 3/8 bolts on the 3 holes on the bottom of the frame. It is important that they mount flush with the bag mount so as not to interfere with the bag when it is mounted. Some factory holes may be used, you will have to drill the rest. 16. Install the air bag and the factory shocks in their new mounts. Be sure to install the bottom airbag mounts prior to fitting in place. 17. Be sure to tighten all hardware after installation for the hangers, radius arms, axle mounts, bag and shock brackets, track bar, and track bar bracket Check again after 50 miles of driving 18. Add and remove air to bags and articulate suspension. 19. Use the heim joint on the radius arms to adjust the axle front to back so it is centered in the wheel wells and use the heim joint on the track bar to adjust the axle side to side.