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Beware of some of the other lightweight, low-cost wheels offered on the market; we've found many of these bend like butter, sometimes just from normal track driving antics, like hitting FIA curbs or dropping a wheel off the track. The value wheels we have listed either have a history of surviving race conditions or are wheels we've had personal success with on the track.
Step two: Reduce body roll, dive and squat
The most important basic suspension trick is to reduce excess body motion. Roll under hard cornering, dive under braking and squat under acceleration all create problems for a driver.
Contrary to popular belief, roll doesn't cause weight to transfer to the outside wheels. Rather, it hurts handling by slowing chassis response to steering, braking and accelerating-all critical inputs for controlling the car.
Body motion also gives the impression the car isn't handling well. Roll, dive and squat all contribute to a lack of confidence behind the wheel. Watch an F1 car in a turn; it nimbly darts around the corner with no excess body motion. Now watch an SCCA showroom stock racer; it leans, squirms and squeals its way around the track. Extreme example, sure, but exactly the heart of the problem.
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More insidious are the other side effects excessive body motion produces. Many softly sprung vehicles will roll and bottom the suspension on one or both ends when cornering hard. This shocks the tires and will cause an instant loss of traction on the end that bottoms first. The result usually involves a tow truck.
Moving the suspension through a wide range of travel can also result in another problem. Most factory vehicles have compromised suspension geometry and several problems can occur when a car heels way over in a turn. First, the suspension can gain positive camber. This is worse in cars with MacPherson strut suspensions. With strut-type suspensions, the car rolls, but the tires don't. This forces the tire to roll onto its outside edge and reduces its contact patch-clearly not the best way to use the tire.
The other evil effect of roll is bump steer. Bump steer is caused when the steering linkage and the rest of the suspension travel in different arcs throughout the range of motion. As a result, the tires can give steering input even if the steering wheel isn't moved when the car heels over. This translates to the driver as a twitchy and unstable chassis. Combine dive and squat and all of these problems add up to a serious lack of control.
Now that you know body motion is bad, what can you do to control it? The first thing to do is run stiffer springs. Stiffer springs will resist roll and bottoming out under roll and combinations of roll, dive and squat.
Of course, stiffer springs have more rebound energy. To prevent your car from bouncing like a pogo stick, you need shocks with more damping. Shocks don't affect how much a car rolls, but they do affect how the suspension responds to bumps and steering input. More rebound damping keeps the car from bouncing and floating over bumps and undulations. More damping also makes the car more responsive to steering input. Too much rebound damping can prevent the suspension from returning once compressed, causing it to pack down and gradually bottom out.
Another way to reduce body roll is to install larger anti-roll bars. Anti-roll bars are torsion bars that connect the wheels. They don't come into play until the car starts to roll in a turn. During roll they must be twisted for the car to lean over. Anti-roll bars don't affect the ride as much as stiffer springs and have no effect on dive or squat. Generally the shock damping doesn't need to be altered when the anti-roll bar diameters are changed.
By Ti Tong
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