1955-57 REAR COIL-OVER SHOCK AND TAPERED LEAF SPRING CONVERSION
1955-57 REAR COIL-OVER SHOCK AND TAPERED LEAF SPRING CONVERSION
We all want our classics to still look like a classic, but to handle like a new car so we add disc brakes, power steering, anti-sway bars and more! The rear suspension on a Tri-Five consists of two leaf springs and a pair of hydraulic shocks just like what they used in the horse and buggy days. You can upgrade the rear suspension with firmer leaf springs and gas charged shocks, but you are still working with 1800's engineering. Installinga complete independent rear suspension (Corvette) is a huge undertaking and will require major frame and sheet metal modifications, not to mention a huge expense. Another option is to install a modern chassis like the fine Morrison units we carry, yet not everyone wants to spend $15,000 to upgrade their chassis.
Classic Chevy has developed a new coil-over shock conversion especially engineered for your '55-'57. It is not a universal street rod kit that must be adapted onto your classic, but a complete turn-key conversion that has been designed to fit the Tri-Five chassis only The kit uses a pair of special tapered leaf springs as trailing arms to properly locate the rear end. These tapered springs attach to the frame using the stock front leaf spring mounting brackets. The coil-over shocks support the weight of the rear of the car and a panhard bar connectsfrom the rear axle housing to the frame to control lateral movement. You may also purchase and install our adjustable traction bars to complete this fantastic kit. This kit can be used with the springs in the stock location or with the CCI Spring Pocket Kit PIN 21-131. After installing this kit the car will handle and corner tar better, will be fully adjustable and will have a super custom look! With the back half of the rear leaf spring deleted there is plenty of room tor larger tailpipes and different gas tank options as well.
Drill and 3/8" Drill Bit
Image #1: The rear end in a Tri-Five is mounted to the rear frame using two multi-leaf springs. Originally they were available in four, five or six leaf designs depending on the car model. The springs were originally mounted outboard of the frame rails. Our display frame has had the rear spring pocket kit installed which mounts the leaf springs parallel with the frame allowing for wider tires.
Image #2: Our project display frame has also had the rear traction bar kit P/N 57-133262-1 installed (refer to March 2006 Classic Chevy Magazine). The traction bars bolt to a plate that is held to the bottom of the lower shock plate using the rear end U-bolts and to a bracket that is welded to the frame at the front of the leaf spring.
Image #3: First place the car on jack stands with the stands under the frame and not the rear end housing. If the car has the CCI traction bars, they will need to be removed first by removing the front and rear mounting bolts for the traction bars.
Image #4: Remove the shock absorbers by removing the 3/4" nuts and flat washers from the lower shock plates. The top of the shock is bolted to the shock bar or the trunk flood board with a 9/16" nut. Remove this hardware as well.
Image #5: There are two U-bolts on each side of the car that hold the rear end to the leaf springs. Remo ve the four 3/4" U-bolt nuts from each side. Now the lower shock plates (and rear traction bar plates) can be removed.
Image #6: With the U-bolts removed, raise the rear end up off the stock leaf springs using a floor jack.
Image #7: Now remove the rear shackles and the front leaf spring eye bolts so the leaf springs can be removed.
Image #8: Our tapered leaf spring is basically the front half of a rear leaf spring yet is made out of a much heavier material and fewer leaves. There are only three leaves in the new tapered leaf springs, which will work as lower control arms for the rear end.
Image #9: The front of the tapered leaf springs include the stock front spring eye bushings allowing the capered leaf springs to mount to the stock front spring mounts or to the spring pocket conversion mounts.
Image #10: The rear end is now held to the new capered springs with four new U-bolts and new lower shock places. The holes in the rear axle spring perches fit onto the spring center pin on the tapered leaf springs just like the original springs. This will maintain the correct pinion angle. The new lower shock plates are made of much heavier steel using a bolt, spacer, washer and nut to hold the bottom of the coil-over shock in place. Torque the U-bolt nuts to 65 lbs.
Image #11: The new shock bar that comes with the coil-over shock conversion must be welded to the frame for needed strength. The new shock bar has the same end flanges as the non coil-over shock bar so it can be bolted into place for locating purposes only: Once the proper location is determined for the new shock bar the frame must be cleaned for welding.
Image #12: The new shock bar mounts with the upper shock brackets to the front of the crossmember and the panhard bar bracket oriented to the rear on the driver's side.
Image #13: Once the shock crossmember is welded in place, remove the mounting bolts and weld up the locating holes in the frame.
Image #14: Now it's time to put on the pretty stuff! The top of the coil-over shocks attach to the upper shock bar using a stud , rubber grommets, washers and nuts just like the stock shocks. The bottom of the coil-over shocks have 1/2" spherical rod ends that attach to the new lower shock plates using 1/2" x 2" bolts and nuts with a 1" spacer between the rod ends and shock places
Image #15: Next the panhard bar needs to be installed. The panhard bar connects from the shock bar to the rear end to keep the rear end from moving laterally: The panhard bar has screw-in rod ends with urethane bushings on each end. The driver's side of the panhard bar attaches to the bracket on the back side of the new shock bar with a 1/2 x 2" bolt with a flat washer and lock nut.
Image #16: The Lower panhard bar bracket must be welded to the top of the rear axle tube on the passenger side. With the panhard bar bolted to the new shock crossmember and the axle housing bracket bolted to the lower end of the panhard bar, the bar will pass over the center of the axle housing and to the passenger side. Support the rear end with a jack and jack stands so it is supported at the ride height.
Image #17: Adjust the threaded ends on the panhard bar so that 1/4" of threads appear past the jam nuts at the ends of the bar. This will center the adjustment on the bar so it can be adjusted either direction once the welding is complete. The bends in the panhard bar will clear the rear end housing as well as dual exhaust tail pipes. From front to rear the bar should be centered over the axle housing. Weld the bracket to the rear end axle tube.
Image #18: The front brackets for the traction bars weld to the frame just under the front spring eye if the car has the spring pocket kit. If the car has the leaf springs in the stock location the front brackets weld to the stock front spring eye bracket on the outboard side of the frame. The rear bracket for the traction bars are held to the bottom of the lower shock plates using the four U-bolt nuts and flat washers that hold the rear end to the new tapered leaf spring.
Image #19: The coil-over shock conversion gives the rear end under the car a great look and leaves plenty of room for large dual exhaust tailpipes and custom gas tanks
Image #20: When ordering the coil-over shock/tapered leaf spring conversions they can be ordered in four versions; stock height coil-overs, 2" lowering coil-overs for 1 and 2-piece frames and the same kits for use with the rear spring pocket kit. The coil-over shocks are fully adjustable so by using the supplied spanner wrench the spanner nut on the bottom of the coil spring can be turned up or down to raise the car 1" or lower the car l "