Over the last couple of issues, we've watched as a relatively stock '68 Camaro underwent a series of specific suspension upgrades. The objective was to illustrate the tremendous gains in handling and performance that's within easy reach with a relatively modest investment in both dollars and elbow grease.
For a bit of background, let's look back a few pages. The Camaro in question was initially driven to California Speedway for a day's worth of baseline thrashing that was to give us an idea of its capabilities in stock form--suspension-wise. For these baseline tests the only thing we did was to replace the existing OEM-style Polyglass tires for a set of modern off-the-rack radials. We then proceeded to run the car through a series of tests consisting of a high-speed 420-foot slalom course, a 200-foot-diameter skidpad, and a series of 60-0- and 30-0-mph brake tests. Once the baseline tests were completed and the results recorded, (we'll get to those figures shortly), we reeled in the Camaro and began the suspension and brake upgrades.
The whole upgrade revolved around the predominant component--the new spindles offered by Heidt's Hot Rod Shop of Wauconda, Illinois. Heidt's "Tall" Dropped Spindles usher in a design advancement that goes well beyond just the lower center of gravity and good looks that come with the addition of standard dropped spindles. In the original suspension design of the '67-'69 Camaro compression of the suspension actually pushed the top of the tire outward, which caused a "negative" camber change. Not a plus for handling, as it causes the tire to tilt outward during cornering compression. This "tilt" lifts up much of the inside portion of the tire patch off the pavement, greatly reducing the available traction in a corner (since less of the tire is on the pavement). To rectify this adverse condition the Heidt's "Tall Spindle" raises the upper ball joint a designated amount. This new, higher position of the outer pivot of the upper control arm changes the arc that it swings in, which actually pulls the top of the tire in a designated amount, thus initiating the "positive" camber change. Positive camber change tilts the top of the tire inward during compression and cornering. Since the car itself usually tilts outward slightly during cornering, the inward tilt of the tire will offset that and keep the tire perpendicular and the tire patch evenly planted on the pavement. It's also extremely important to note that there is an optimum position for the upper pivot in this particular suspension package, using all the other pivot points as is. Too high of an outer, upper pivot will cause too much camber change, and may also cause bump-steer, since the spindle is being pulled in so much during compression.
Above and beyond the installation of the Tall Dropped Spindles the original front suspension was replaced by a quartet of Heidt's tubular control arms. Though the company offers tubular arms in standard dimension, they also offer short arms that narrow the front track width by a total of 2 inches (1 inch per side) allowing the use of wider wheels and tires and eliminating interference during extreme cornering. Another option (and the one we chose) was their lower tubular arms designed specifically for use with coilover shocks rather than OEM-type coil springs. We matched the spindles and control arms with a corresponding 1 1/8-inch-diameter anti-rollbar (also available from Heidt's), a quartet of dual-adjustable QA1 shocks (coilovers up front), and a Wilwood performance disc brake setup, as well. At that point we were more than ready to run the follow-up road tests. We gathered up the crew, our test equipment, and our cameras, and headed back to California Speedway.
The conditions (both weather and track) were nearly identical to the original (this is SoCal after all) so we went ahead and set up the tests as we did initially. Now, in all honesty we did expect improvement above what we quantified under stock conditions--what we didn't really expect (though we were hopeful) was the extent of improvement that we witnessed--much to our delight, by the way. That said, it's time to get to the crux of the biscuit--the results.
The best times with the car as originally tested (fresh, but in stock configuration) stacked up like this (look for the complete result elsewhere in the story). In the 420-foot slalom, the Camaro posted an elapsed time of 6.80 seconds at 42.1 mph; The 200-foot-diameter skidpad test produced a best of 12.98 seconds counter-clockwise and 12.50 seconds clockwise averaging out at 12.74 seconds and equaling 0.76 g's--a respectable showing. The braking portion of the test produced 60-0-mph measurements of 201.07 feet on the initial try, and 197.39 feet on the second--a distance that'd make me think twice about tailgating, that's for sure.
The first retest consisted of the exact same parameters and conditions as the baseline but with the aforementioned suspension upgrades. This round of testing saw the Camaro gain considerable improvements over stock, in fact nearly exactly what we'd been hoping for. The 420-foot slalom time decreased to 6.52 seconds, and speed through the course increased to 44.1 mph. The skidpad results were equally impressive. With the suspension upgrades, the Camaro cut its time to 12.60 seconds counter-clockwise and 12.44 seconds clockwise. This time around, the brake test showed a great improvement. The Wilwood conversion certainly did its job. First try netted a 60-0 mph of 169.76 feet, and the second (with the brakes warmed up a bit) a 149.94 feet--a much safer distance, for sure.
The final retest was performed with the addition of a quartet of Nitto NT-01 performance tires in place of the off-the-rack radials utilized previously. The intention behind this was to enable the vehicle to take full advantage of the potential offered by the performance suspension we'd installed. After all, improving the suspension in the manner that we did just moved the weakest link in the performance chain from the inadequate OEM suspension to the second and often most overlooked variable--traction.
Being relatively new to the true high-performance genre (remember, I've always been a pre-'48 street rodder versus a racer), I was amazed at the difference an exceptional set of tires could make. Sure, the improvement we'd gained up to this point was remarkable, but I'd never known that good rubber was such an important factor in making performance suspension components perform to their maximum potential. With the final piece of the performance puzzle in place, the suspension upgrades indeed showed their worth. The slalom time was now reduced to 5.92 seconds and speed jumped to 48.5 mph! The skidpad dropped to 11.60 seconds counter-clockwise and 11.58 seconds clockwise! Heck, the 60-0-mph brake testing benefited considerable, as well--shortening up to a confidence inspiring 138.35 feet.
These comparisons and test results lead to only one conclusion: If you want get the most out of your performance car, pay as much attention to its suspension, brakes, and tires as you do to its driveline--you won't be disappointed!