Q&A: Bill Hickok Of Hickok Racecars
CHP: What is the most critical aspect of successfully running a small tire in a Drag Radial or E.T. Street class?
Bill Hickok: It all comes down to how well you load, or plant, the tire. This is critical to how much traction you have. In a heads-up Street class, you have to have a good footprint on the track to hook. On leaf-spring cars, we run John Calvert's CalTracs systems. These bolt-on traction systems work exceptionally well, and it's also important to run a good double-adjustable shock.
CHP: Why a double-adjustable shock?
BH: Double-adjustable shocks allow you to adjust the shock so that the bump and rebound functions can occur separately, from soft to hard, and also provide predictable action. This allows you to tune how the car's suspension acts on a specific track, and the adjustments can be done by simply turning a knob on the shock while it's installed in the car. We like to use Strange, Koni, Rancho, QA1, or VariShock shock absorbers.
CHP: How much weight balance should you have over the rear wheels, and how should you measure for it?
BH: You'll need to weigh the car on four wheel scales with the driver in the driver seat and the car at race weight. The goal you are trying to achieve on the rearend is even distribution of load under acceleration. It's also important to consider the vehicle's rotational torque. This means that under acceleration, the car's weight shifts from the left front corner to the right rear. It's great to have lots of horsepower, but if you don't have it properly balanced, it's all for nothing. A lot of measurements go into an efficient and effective suspension setup. Leave these adjustments to a qualified individual who knows what he's doing. It's easy to get lost when inexperienced people start making adjustments and are unsure of the outcome. That's how cars get dangerous.
CHP: How do you define instant center?
BH: Instant center is the imaginary point where the upper and lower four-link bars cross paths in front of the rearend. In general, a good starting point is 5-7 inches off the ground and 50 inches or so ahead of the rear axle's centerline. Horsepower levels, tire size, weight, and chassis predictability will determine any additional adjustments beyond that.
CHP: How should rear rim width relate to rear tire width?
BH: We've found that the most stable package is to have the rim width at about 1 inch larger than the rear tire contact patch. This especially helps keep the car stable on the big end of the track, where high speeds come into play.
CHP: What are the differences between using chrome-moly or mild steel in the manufacture of 'cages?
BH: Mild steel was used for several years, but in comparison, it is almost three times heavier than chrome-moly, is not as strong, and flexes more. Because chrome-moly is stronger, it is possible to use thinner-gauge materials that are still stronger than mild steel. With chrome-moly, you not only have the added strength and reduced weight, but also a more rigid 'cage. This helps tremendously to keep the car more rigid, which also adds to its consistency.
CHP: What are some of the differences between a four-link system and ladder bars?
BH: A ladder-bar system is a simpler traction device used to enhance leverage on the rear tire over stock configurations. It is not as adjustable as an aftermarket four-link system, but it is easier to install and less expensive. A ladder-bar system in general is about 32-36 inches in length and has a short, nonadjustable instant center, which can work well on moderate-horsepower, small-tire cars in the 9- to 11-second range. So a ladder-bar system works similar to a short four-link setup. A good aftermarket four-link is much more tunable and uses eight Heim joints and numerous mount locations, as compared with the two pivoting Heim joints and limited mount locations used on a ladder-bar system. Four-links are much more efficient in applying the power to the ground. In the heads-up world of racing, four-links are not allowed in every class and a good ladder bar is the next best thing.
CHP: What are some of the differences between a long wheelie bar and a short wheelie bar in application, and what testing procedures can be used?
BH: A short wheelie bar is typically used on a moderate-level race car, such as a 9- to 11-second car that exhibits lots of weight transfer and needs to limit the front end from coming too far off of the ground. A very high-horsepower car that runs in the 8- or sub-8-second range uses a long wheelie bar because it is more rigid and helps stabilize the car at the launch and limits excessive front-end travel. They can be staggered in contact height to preload the car at the starting line to allow the car to leave straight. By adding chalk on the wheels, a member of the crew can inspect the starting-line surface and use the chalk mark as a footprint to make changes from. The chalk mark will also show how far out of the hole each bar was contacting the ground.