Classic Performance Products 175 East Freedom Avenue Anaheim, CA 92801

1955-'59 Chevy Pick Up Rear Leaf Spring Kit


'35-'48 leaf springs    


3/4" bump stops    

7/16" flat washers

leaf spring brackets

5-hole plates

3/8-24xl/4" bolts

1/2-20x4" bolts

shackle brackets

spring pads

3/8-24 nylox nuts

1/2-20 nylox nuts

'35-'48 shackles


3/8" flat washers

1/2" flat washers

shackle pins

shock brackets

7/16-20 nylox nuts

3/8-16 nylox nuts

shackle bushings

shock studs

7/16-20x4" bolts

Installation Notes:


While it may be possible to install this kit without removing the bed, it is recommended that you do so, as it is much easier. Support the front and rear of the chassis on jack stands. Be safe! Avoid pulling and pushing on the vehicle while it is off the ground.


Remove the rear axle, springs, and brackets. To remove the rivets holding the brackets, grind the rivet heads flush. Center punch the rivet and drill through using progressively larger drills up to a 5/16" drill. The rivet should be relatively easy to punch out. If it is not, then continue drilling with a 3/8" drill. Take care not to drill the original rivet holes larger or off center, as you will be locating your new parts with these holes.


Install the leaf spring brackets on the outside and underside of each rail. The brackets mount in the same manner as the originals by bolting on the outside and bottom of the rail. The brackets mount with the leaf spring hole in the rear. Fasten the brackets to the sides of the rails using the holes of the original brackets and 3/8-24xl-1/4" bolts, nylox nuts, and one washer under each nut. It may be necessary to align-drill a couple of these holes. Use the bracket as a template for drilling the remaining holes of the bracket and continue bolting together as you go. There should now be 7 bolts holding on each bracket.


Install the shackle brackets. The brackets are orientated on the rails much like the others with the shackle mount hole closest to the front of the vehicle. Bolt the brackets to the rails sides using the holes of the original shackle brackets. It may be necessary to align-drill a couple of these holes. Use 3/8-24xl-1/4" bolts, nylox nuts, and one washer under each nut to fasten each bracket, then drill out the other holes using the bracket as a guide. Bolt up the holes as you go.


Install bump stops. The new bump stops are mounted under the frame rails 5-3/4" in front of the shock cross member. Drill 3/8" holes 7/8" from the outside edge of the rails and fasten with 3/8-16 nylox nuts and washers.


Weld spring pads on the axle. The spring centers are 37.5" and should angle the pinion 3º up. Most people will skip this step, for right now.


Install the springs. Use the ½-20x4" bolts and nylox nuts to fasten the front of the spring into the front brackets. To make things easier, you may want to put the rear-end on a floor jack and roll it into position, keeping it raised and out of the way of the springs. Place the shackle bushings into the spring eyes and the shackle bracket. Slide the shackle pins through a shackle dog-bone and the bushings. Raise the rear of the spring and attach to the brackets using the shackle dog-bones and nylox nuts.


Set the rear-end onto the springs with spring pads in between. Center the rear-end and clamp the axle to the springs using the u-bolts, the 5-hole plates, and 1/2-20 nylox nuts. The 5-hole plates are positioned under the spring with the shock tabs pointing down on the inboard side and behind the axle. Typically, the spring pads are 3º down from the pinion, but just get this close for right now. Later, the final step will be to set the vehicle on the ground and to check that the pinion angle is 2º lower than the transmission angle. The pads can be welded on after the spring pad angle has been checked and repositioned if necessary.


The new shock brackets mount outboard of the original shock brackets. Drill 7/16" holes 3.5" outboard of the upper rivet of the original shock bracket and 1-1/8" below the top edge. Bolt the brackets and shocks on to the cross member. Use 7/16-20 x 4" bolts, nylox nuts, and washers under the bolt heads and nuts. Set the bottom edge of the brackets parallel to the cross member and drill the 3/8" holes using the bracket as a guide. Bolt in place using 3/8-24x1-1/4" bolts, nylox nuts and washers.


Fasten the shock studs to the 5-hole plate with 1/2-20 nylox and washers. Attach the shocks and fasten with 7/16-20 nylox, stainless steel cupped washers, and flat washers.


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