Ever wonder why those trucks you see sitting flat on their framerails have front wheels that lean inward at a 45-degree angle? The answer is camber. Camber is the measurement of tire lean in degrees. If the top of the tire tilts inward, the vehicle has negative camber. Typically, a truck at stock height is set with about a 1/2-degree of negative camber for optimum performance. When a truck is lowered by using coils, the suspension is now set higher in its arc of travel–thereby increasing the amount of negative camber. Oftentimes, the effects of simply installing a shorter coil can be corrected by installing shims or rotating a cam to push the upper control arm out. But once you lower the truck beyond what can be corrected by adjustment, you will be forced to “set the toe and let it go,” which is what most alignment shop guys say when they see a lowered truck pulling in for service.
Fortunately for all of us ’63-72 GM truck owners, Performance Online has come to our rescue. In addition to offering just about everything you need chassis and suspension wise for ’47-72 Chevys, ’48-56 Fords, and ’55-72 GM cars, they recently developed tubular upper control arms that help to correct the geometry on moderate to severely lowered rides such as mine. Besides looking really cool, the arms are 3/8-inch longer than stock. This means you can align even the lowest of trucks. They also moved the location of the upper ball joint slightly rearward to add an extra 2 degrees of caster to the arm–helping the truck to drive straight and true. Finally, the angle of the ball joint was rotated slightly so it would meet the spindle at the correct angle. The tubular control arm kits come with brand-new factory cross shafts already installed. Performance Online also offers new bumpstops and all three of the possible ball joints for your application– giving you truly one-stop shopping.
I rolled Old School into the Performance Online installation center at about 9:00 a.m. and was back on the road by 11:00 a.m., so needless to say, this is a simple installation. As always, contact Performance Online for more information on this or any other product they carry…
View entire article | Source: Classic Trucks | Posted: 02.2009