Speed Direct Shark Bite Suspension - RearendedProject C3 Triple-Ex Gets A Shark Bite Coilover Rear Suspension From Speed Direct August 30, 2010 By Dave Young Photography by Dave Young
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The transverse leaf spring... The transverse leaf spring in early Corvettes keeps them from having truly independent rear suspension. This month we'll address that handicap by installing Speed Direct's Shark Bite rear coilover kit. During an era when most manufacturers were still building vehicles with straight front axles, GM realized that true automotive enthusiasts sought to corner and brake-as well as accelerate-and engineered the underpinnings of the C2 Corvette (which later carried over into the C3) to facilitate this. This suspension-which combined independent coil springs and control arms up front, and a fixed center section with independent trailing arms in the rear-was unheard of in a domestic vehicle for the time. The technology worked very well, providing arguably the best-handling mass-produced domestic cars of the mid-'60s and well into the '70s. But as technology advanced, the C2 and C3 suspension started to show its age, as well as its drawbacks. In what was almost certainly a compromise between physical space, economics, and the manufacturing technology of the period, GM chose to use a single multi-leaf spring to support the rear of these Corvettes. Mounted laterally, or transversely, the spring is bolted firmly to the center section of the rear differential in the middle, with each side of the spring supporting the weight of one half of the rear of the car. While this configuration does allow each side of the suspension to travel independently up to a point, one of the drawbacks of the transverse spring is that suspension movement on one side is invariably transferred through the spring, which has an effect on the opposite side. As an example, if, while cornering, the inside rear tire drops due to a low spot or pothole, the outside tire can unload briefly, negatively affecting the car's adhesion. While there are modern composite mono-leaf springs available that help with this problem, we sought to eliminate the transverse spring from our car completely and convert it to a truly independent rear coilover suspension.  There's no doubt that the...  There's no doubt that the midyear-through-C3 independent rear suspension was ahead of its time. One drawback, however, is the transverse leaf spring connecting each trailing arm to the center section of the differential. This month we'll install Shark Bite rear coilovers and eliminate the leaf spring completely.  Since the natural arc of the...  Since the natural arc of the leaf spring can cause a jack to slip, we installed a C-clamp on the spring before using a transmission jack underneath it to relieve tension.  With the spring compressed...  With the spring compressed slightly, the endlink can be removed and the spring dropped. The trailing arm will keep the suspension from dropping excessively. Repeat this procedure for the opposite side. Having been impressed with the front suspension components from Speed Direct that we installed on Project C3 Triple-Ex last month, we began researching our options on by visiting www.speeddirect.com. The company's Shark Bite rear coilover kit is advertised as being all inclusive, offering either single- or double-adjustable shocks and a multitude of spring rates to accommodate the driving habits and ride-quality preferences of any Corvette owner. Even better, thanks to Speed Direct's proprietary rocker assembly, everything bolts in place of the factory components with no welding or grinding required. Since our car will see a combination of street, track, and likely autocross duty, we liked the idea of adjustable shock absorbers and a stiffer spring rate for our suspension. If this were a dedicated track car, the double-adjustable shocks would exponentially expand our tuning options, but for this car's purposes, single-adjustable units will keep suspension tuning simpler while still offering far better adjustability than the factory setup. The other decision we had to make was which spring rate would be appropriate for our car. In general, springs with softer rates offer a smoother ride but sacrifice handling by not keeping the tire firmly planted at all times. As a rule, we're prone to sacrificing the ride quality of our Corvette if it means improved handling, so we opted for the 400-in/lb-rate coil springs. Let's face it: If we cared that much about ride quality, we'd be in a Cadillac, not a Corvette. Even so, springs with a lower spring rate are appropriate for cars that see mostly street duty, and the Speed Direct rear kit offers the best of both. By simply jacking the car and supporting it, the rear coilovers can easily be removed for spring changes, offering the advantage of running a soft spring in normal driving and swapping in a stiffer one if you plan some autocross or track time on the weekends. We'll likely try different spring rates on our car later on, but for now we'll be using the stiffest springs offered, for maximum cornering capability and traction. (Frankly, we own performance cars because we enjoy driving aggressively, ride quality be damned.)  The leaf spring is held to...  The leaf spring is held to the differential with four, half-inch bolts. Have a friend help you here, as the spring is heavy (around 45 pounds).  You might have to drop your...  You might have to drop your exhaust to remove the rear spring; we were lucky, and snaked ours out one side.  The factory shocks can also...  The factory shocks can also be removed permanently, as they'll be replaced by the adjustable shock absorbers in the Shark Bite coilover system.  With our factory components...  With our factory components out of the way, we removed our new parts from their packaging and took inventory. Our kit was complete and well thought out, including everything needed for the installation.  The first step is installing...  The first step is installing the center bracket on the rearend. This piece bolts right where the leaf spring was attached, using hardware provided with the kit. These, and most fasteners in this kit, need a bit of threadlocker prior to being assembled. The instructions are very clear as to where to use threadlocker, and also give specific torque specs.  Moving outward, the rocker...  Moving outward, the rocker and bracket can be pre-assembled, then installed using the factory provision for the crossmember and supported by a bracket to the differential cover. Only do one side at a time here: if you remove both crossmember bolts, there is very little supporting the center section, and it may drop. The Speed Direct rocker is... The Speed Direct rocker is a proprietary design, allowing the coilovers to be installed at a transverse angle, where the leaf spring used to be. The result is a very clean-appearing, functional coilover suspension for early Corvettes. Once our parts arrived from Speed Direct, we took a quick inventory, comparing the parts to the list provided and verifying that we had everything we needed for the installation. The parts were professionally packaged in a combination of bubble wrap, plastic, and papers, ensuring that none of the powdercoated parts were damaged during shipping. All of the parts and packages were also clearly marked with the part number, description, and orientation (right or left), which really helped make the job easier. The Speed Direct instructions were clear and concise, and the only special tools we needed were a torque wrench and snap-ring pliers, which we had, and the spanner wrenches that came with the kit. If you have average mechanical skill and a good set of handtools, this is an easy do-it-yourself job you can accomplish over a weekend. With the advantage of a vehicle lift, it took us about six hours to remove our factory suspension and install the Shark Bite coilovers and related components. Putting the vehicle back on the ground, we made a preliminary ride-height adjustment, drove around the block to allow the suspension to settle, then put the car back on the lift to check all the fasteners and reset the ride height. While our initial impression of the rear coilovers during the testdrive was very favorable, with stable handling, a smooth ride, and nimble steering response, we couldn't really put the car through its paces just yet. Because we lowered the ride height of our Stingray by an inch and a half, we'll need to set wheel alignment and corner weights with four-wheel scales before taking it to Gainesville Raceway for some serious track testing. Stay tuned as we perform these steps on Project C3 Triple-Ex in a future issue of VETTE.  We appreciated the completeness...  We appreciated the completeness of the kit from Speed Direct, as well as the clear and concise instructions. The package included every piece that would be needed, and an inventory sheet was provided to make hardware selection easy.  The trailing arm brackets...  The trailing arm brackets are two pieces, encasing the factory trailing arm. They use factory provisions to attach to the car, with no drilling or modifications required.  A male/female Heim joint is...  A male/female Heim joint is used to connect the trailing-arm bracket to the rocker. This can be bolted in place and torqued to the specification provided in the instructions.  The Shark Bite rear suspension...  The Shark Bite rear suspension comes with your choice of either single- or double-adjustable shock absorbers. We chose the single-adjustable shocks for our Stingray; these offer 12 simple rebound adjustments for various driving and track conditions.  Before assembling the springs...  Before assembling the springs onto the shocks, we installed one of the new shock adapters provided with the kit, then installed the proper bushings using snap-ring pliers.  We love the look of our newly...  We love the look of our newly lowered Stingray, and are looking forward to better handling, quicker quarter-miles, and lower lap times. Overall we're very impressed with Speed Direct's products and look forward to putting them through their paces both on the road and at the track.  Once assembled, the coilover...  Once assembled, the coilover installs using a clevis pin through the rocker and a through-bolt at the differential bracket. The springs should be preloaded slightly, about one-half inch, before you check ride height.  With the wheels back on the...  With the wheels back on the car, it can be placed on the ground and bounced a little to settle the suspension. A tape measure can then be used to check ride height.  Thanks to the provided spanner...  Thanks to the provided spanner wrenches, ride-height adjustments are easy. We chose to lower the stance of our Stingray about one inch all the way around. This much drop will require a wheel alignment after we drive the car a little to allow the suspension to settle. In a future issue, we'll perform a four-wheel alignment and set corner weights with wheel scales before heading to the track for hard-core testing.  The rear coilover suspension...  The rear coilover suspension doesn't just look better than the factory equipment, it weighs less and offers adjustability not found with factory components.
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