Rebuilding the C3 Corvette Independent Rear Suspension
Pre-Assembled Replacement Parts Make it Easy
1. Rebuilding the C3 rear suspension can be accomplished with some basic safety measures, a good selection of hand tools and some backyard mechanical ability. Paul Taylor of Hot Rods by Dean handled the hands-on chores that we followed.
Our 1968 Corvette coupe is edging ever closer to hitting the highway. After rebuilding the front suspension and brakes, the team at Hot Rods by Dean turned their attention to the rear suspension. For those readers who are new to this project, the car is being done as a "gentle restomod," or as we like to call it a "modernized restoration."
For the most part the car retains its factory design, but with subtle upgrades to improve handling and performance. These modifications will go a long way to improving performance, reducing maintenance and enhancing the appearance of the car. Likewise, this car is being built to enjoy. It's never going to be a 100-point restored car, rather, we will be using the car frequently. And that was the reasoning behind the leather-covered seats rather than vinyl, QA1 shocks on all four corners, Coker radial rubber, a modern 350 with a Chevrolet Performance serpentine belt system and the list goes on. However, the car remains on the original chassis and the entire refurbishing process is being done without lifting the body off the frame and so far no welding has been involved in our chassis work. In short, we are tackling this project much like many backyard enthusiasts would approach their own Corvettes.
While the C3 Corvette is no match for a modern Corvette, the engineering and design of the car is still good enough to provide a rewarding and reliable driver when the original components are brought back to "as new" or better condition. The great news about working on Corvettes is virtually every part of the suspension and braking system is available new and there are also numerous upgrades available. This wide selection of parts has made rebuilding a Corvette's suspension a true bolt-on process.
While parts are available to rebuild original components (such as the rear trailing arms), brand-new, powdercoated units are available from The Right Stuff (as they use Lonestar Caliper Company components) and all you need are good hand tools and a bit of mechanical know-how to install the new units. These brand-new trailing arms eliminate the need for pressing in bushings and installing bearings and seals. The parking brake parts are installed along with new proper dust shields and the new trailing arms are powdercoated. In short, this is a true bolt-on rebuild.
Once again, we went to the mild side on our '68 T-top coupe. The C3 Corvette stopped just fine when they were new, so we opted for a set of original-style rear calipers from The Right Stuff (prepped by Lonestar Caliper Co.), matching the original calipers up front. While the exterior of the new calipers appear stock, internally they have stainless steel sleeves with O-ring seals installed by Lonestar rather than the old factory-style lip seals. This improvement greatly increases sealing capabilities and the life of the calipers.
When it came time to restore the rear transverse leaf spring we faced the same dilemma: repair or replace? Once again we opted for a brand-new replacement nine-leaf spring from Detroit Eaton Spring. (Here, shortly, we will be fitting the '68 with an original rear sway bar from Corvette Central.) This cut down on time spent disassembling the old spring, grinding rust, replacing rubber parts and painting. This was as simple as opening a cardboard box and removing a brand-new, painted spring. The original shocks were deep-sixed and replaced with a set of aluminum-bodied, fully adjustable QA1 shocks. We cleaned and painted the original strut bars before installing new Energy Suspension urethane bushing in the refinished bars.
Two brand-new halfshafts from Inland Empire Driveline pass the power from the differential to the wheels. It should be noted that the C3 Corvette has two different attachment methods for the halfshafts. The small-block cars utilize U-bolts to hold the universal joint to the centersection while big-block cars utilize heav- duty caps to mount the universal joint to the centersection. The final piece attaching to our refurbished rear suspension is a new steel driveshaft from Inland Empire Driveline. This will ensure silky smooth power transmission to the differential. As you can see, in most cases we used new components rather than reconditioning the original parts. We went this route in the interest of time and in an attempt to make our rear suspension truly as close to brand new as possible.
New rubber brake lines were installed and the parking brake cable from Control Cables was connected. From there we moved under the hood to install a new power booster and master cylinder. We simply don't believe in using 50-year-old brake parts, so both the master cylinder and power booster were replaced using original-style components from Lonestar Caliper. We used a depth gauge from Lonestar Caliper to be certain our master cylinder pushrod was set to the proper depth. The rod should contact the master cylinder piston, but not depress the piston. Once we were certain the rod was set to the proper depth, the master cylinder was mounted and the entire system was bled starting with the master cylinder and then working to each caliper. We used quality AMSOIL DOT 4 brake fluid.
Speaking of new, in keeping with our approach of maintaining the factory appearance we ordered a new set of Rally Wheels and Red Line radial tires from Coker Tire. The wheels come finished in the perfect factory silver finish and we opted for Red Line tires as a nod to what a high-performance tire looked like in 1968. While these tires have the sidewall and tread look of a vintage nylon tire they are actually constructed on a radial tire core so you now have the best of both worlds, vintage looks with all the benefits of a radial design tire. Rally caps and beauty bands from Coker Tire will give the wheels a finished look.
After the suspension was completely assembled we set the toe-in using the original number of shims on each trailing arm and dialed in the camber using the eccentric nut/washer on the strut rods and a simple wheel camber gauge. When the car is complete we will take it in for a four-wheel alignment, but this method will get us close enough for a shakedown run.
And so we are just about finished with any work under our C3 project car. We are pleased with the ability to improve the car without straying too far from the original design. We feel certain this blend of parts will provide a car that is fun and entertaining on the open road. We can hardly wait. Vette
1. Rebuilding the C3 rear suspension can be accomplished with some basic safety measures, a good selection of hand tools and some backyard mechanical ability. Paul Taylor of Hot Rods by Dean handled the hands-on chores that we followed.
2. To remove the trailing arms, the rear spring must be disconnected from the trailing arm. Even in the relaxed position there is pressure on the spring. A scissor jack with a piece of 2x4 under the spring will take the tension off the spring link. Be very careful working with springs.
3. On the front side of the rear wheel we can see the brake line and parking brake cable that must be disconnected, and the shock absorber must also be unbolted from the lower mount. Since we are replacing the rear shocks we also removed the upper bolt to remove the shock absorber.
4. With the spring safely disconnected from the trailing arm, the hub is supported with a scissor jack or jack stand. Note the shock absorber has now been removed and the parking brake cable has been disconnected at the chassis along with the brake hose.
5. The front of the trailing arm is held in place with a single bolt. On either side of the bolt you will find shims. These shims set the toe-in on each wheel. Carefully remove the shims and label and bag them as "inner" or "outer" shims. You will reinstall these shims later to maintain alignment.
6. At this point you can sandblast the original arms, install bearings, seals, bushings and brakes or you can simply order a brand-new, powdercoated set of trailing arms from Lonestar Caliper and bolt the arm in place. We opted for the brand-new approach.
7. The Lonestar Caliper trailing arm is completely assembled, including all-new parking brake assembly, bearings and front bushing. Even the new dust shield is installed. Using these new units saved us a lot of time.
8. Taylor uses the scissor jack to support the new Lonestar Caliper trailing arm. Be certain the hub is safely supported and then carefully align the front bolt hole.
9. We sandblasted and painted the shims silver before carefully installing them back in the original location. After the shims are in place we used new hardware in the front trailing arm. The bolt and castle nut should not be torqued to the final 50 ft-lb spec until the car is at ride height. Don't forget the cotter pin.
10. With the new trailing arms bolted in place we turned our attention to installing new halfshafts from Inland Empire Driveline. Once again, brand-new units ensure high quality and save time.
11. The halfshaft has two distinctly different ends; this end bolts to the trailing arm with this flange.
12. The opposite end uses typical U-bolts to attach to the differential. Do not overtighten the U-bolts as overtightened U-bolts can cause damage and/or vibrations. The recommended torque for the U-bolts are 17 ft-lb.
13. We removed the back cover on our differential and did a thorough inspection. Satisfied that it was in good working order we simply added new AMSOIL gear lube and a tube of limited-slip differential additive.
14. Since the outer 5/8-inch flange bolts do not apply any force on the universal caps they are torqued to 75 ft-lb. As always, it is best to "step torque" the bolts in three increments to avoid mounting flange problems. We did 25, 50 and finally 75 in a cross pattern.
15. After we installed new Energy Suspension urethane bushings in the strut bars we installed them by connecting to the lower shock mount and the bracket on the chassis. The strut rods are used to set the camber on the rear wheels. After the camber is properly adjusted, the outer nut is torqued to 75 ft-lb, while the inner bolt on the chassis is torqued to 70 ft-lb.
16. The camber for each rear wheel is set independently using this eccentric bolt and washer arrangement. We had marked the location of the eccentric prior to disassembly. We will use that mark for our initial setup but the car will receive a four-wheel alignment later.
17. We continued our approach of making the rear suspension brand new by purchasing a new nine-leaf rear spring from Detroit Eaton Spring. With brand-new liners between the leaves, fresh paint and no fatigue from 50 years of use, new was definitely the way to go.
18. The new spring was installed using new hardware. These bolts are torqued to 70 ft-lb and again we brought the torque up to spec in three stages. It should be noted the hardware is all new and the bolts are properly rated to handle the load.
19. With the new spring clamped in place it is time to connect the spring to the trailing arm. Once again use caution when loading a spring as the stored energy can be dangerous. Work slowly and carefully. The new drop link bushing and bolt have been installed in the trailing arm.
20. This cup will receive the new rubber bushing from the drop link that connects the spring to the trailing arm.
21. A short piece of 2x4 is locked in place by the spring cup while a scissor jack will slowly raise the end of the spring upward. Be certain you are only raising the spring leaf and not the entire car. Be safe, be observant.
22. Once the spring is raised high enough the lower rubber bushing is pushed into place and the castle nut is threaded onto the nut.
23. A cotter pin ensures that the castle nut will remain in place. The drop link bolt should not crush the rubber bushings.
24. While we could have easily ordered new rotors, we discovered our rotors exhibited very little wear. A quick turn in the Hot Rods by Dean brake lathe and they were as good as new.
25. Our original rear calipers were frozen so we ordered a new set from The Right Stuff (Lonestar Caliper Co. components). While these units look factory fresh they actually are vastly improved with stainless steel sleeves and O-ring seals.
26. After bolting the caliper to the original brackets it was a simple matter of dropping in a pair of new brake pads.
27. The retainer pin slips through both sides of the caliper and both brake pads before the cotter pin is installed to retain the pin.
28. And there you have it, new spring, halfshafts, brakes, trailing arms and strut rod bushings. Our rear suspension is better than new.
29. The final piece to the rear suspension is these QA1 aluminum-bodied shock absorbers. Shock absorber technology has made tremendous strides since 1968; these new shocks will go a long way to making our C3 ride and handle superior to anything available when the car was built.
30. QA1 builds a shock that is the perfect bolt-on for our application. Remember to keep the adjuster knob face forward for easy access. Adjusting the shocks for street, autocross and track days is as simple as turning the knobs.
31. Once again, the scissor jack was employed to raise the trailing arm a bit so we could bolt our QA1 shock to the factory mounting bracket on the chassis.
32. It pays to inspect the upper shock bracket for any signs of damage. In keeping with the rest of the rear suspension, we used all-new hardware specifically designed for this installation. This last bolt completed our rear suspension.
33. With brand-new calipers from The Right Stuff (Lonestar Caliper) on all four corners we moved into the engine bay to install a brand-new power booster, from Lonestar Caliper as well.
34. We also ordered a factory-style dual master cylinder from Lonestar Caliper. By staying with the stock brakes we are able to use this master cylinder, which goes a long way to a factory appearance under the hood.
35. After removing the 50-year-old booster and master cylinder we cleaned up the firewall area and hit it with a little Summit Racing Chassis Black paint.
36. Once again, because we opted for factory-style disc brakes, the new power brake booster was a direct bolt-on item. Four nuts inside the car hold the unit in place.
37. Here we have the pushrod installed to the proper depth and we are ready to install the master cylinder. The pushrod should contact the master cylinder but not depress the cylinder.
38. We bolted the master cylinder in place and before connecting the lines to the master cylinder we "bench bled" the unit. Then the lines were connected to the master cylinder and we bled all four brake calipers until we had a good, firm pedal.
39. The crowning touch on the car is a full set of redline tires and factory silver Rally Wheels from Coker Tire. This is the ultimate factory high-performance look. Don't let those vintage sidewalls fool you, the Coker Red Line tires are built on a modern radial tire core resulting in vintage good looks with modern safety and handling. And with that our 1968 Corvette is truly "ready to roll."
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