The pursuit of conquering the challenges of track conditions by utilizing suspension has become a very sophisticated and precise art, and has greatly evolved since the early days of drag racing. As vehicle horsepower has increased, tire design, track preparation, and suspension components have advanced drastically over the years.
Over time, shock and strut manufacturers have identified the proper valving and design to take full advantage of track surface composition. To further address the need for advancement, Afco Shocks and Menscer Motorsports partnered to develop a unique relationship that has led to new frontiers in shock design. Menscer utilizes a private labeled and designed Afco shock body to perform custom adjustments, dependent on the individual racing application. This collaboration results in highly competitive custom shock package.
Afco and Menscer-equipped rides are a staple at radial tire events around the country. Radial and small tire racing has become exceptionally popular over the past few years, with traction and track prep taken to a fine art. This practice of grooming gives way to superb track surfaces that have a tremendous amount of grip, and allows manufacturers the ability to optimize shocks for ideal launch and traction control, leading to outrageous 60-foot times and sub 3-second 1/8-mile passes.
In this story, we’ll be taking a look at the installation of a set of Menscer Motorsports shocks to the rear of our Dragzine Project Evil 8.5, and diving into the advantages of installing custom-designed shocks on a race car to provide it with unparalleled performance on the track.
Advantages Of Custom Shocks
Compression– A motion during which the tire travels upward, relative to the vehicle, compressing the spring and shock absorber.
Rebound – A motion during which the tire travels downward relative to the vehicle, and the spring and shock absorber extend.
Damped, Dampened – A force or action opposing a vibrating motion to reduce the amount of piston vibration.
Pressure Tube – The sealed tube in which the oil is under pressure from the gas (usually nitrogen) that the rod and valved piston stroke through during compression and rebound cycles.
Cavitation – The oil used in hydraulic shocks contains approximately 10 percent air. Under load, the air and oil molecules separate (foaming), resulting in a noticeable drop in the damping force.
Valving – The damping values shock engineers have selected through the use of certain springs, shims, and orifices in the piston to control the flow of fluid through the piston as it moves through the shock body to achieve certain track performance outputs.
Bypass Controls – Bypass controls divert oil through bypasses to divert the oil past the piston in order fine tune the movements of the shock.
When constructing a specialty shock, there are a number of factors to take into account, such as the type of suspension, as this will determine the type of valving package required. A stock suspension car is going to have unique needs, and a lot more movement of the suspension to apply the tire correctly to the racing surface. This is due to the explosive conditions of a launch, as the shaft receives a substantial amount of input from the rear suspension. In comparison, a chassis car or a ladder-bar will not require as much travel to accomplish the same effect.
“Traditionally, with stock suspension to achieve optimal traction, the suspension needs to have more anti-squat to achieve proper rear suspension movement, and apply the tire correctly,” said Eric Saffell of Afco Shocks. “That requires unique valving to help control the additional amount of travel.
“We have to do different things inside the shock valving to control how much travel and dampening are applied to achieve proper launch scenarios. We achieve this by going inside the shock valving to make key adjustments to the low and high speed movements of the shock,” continued Saffell. “The shaft velocity is at its highest rate of speed during the initial launch, and understanding what speeds the shocks are subjected to allows us to use the dampening control and adjust how much hit is applied to the tire.”
Traditionally, with stock-suspension to achieve optimal traction, the suspension needs to have more anti-squat to achieve proper rear suspension movement, and apply the tire correctly. – Eric Saffell, Afco Shocks
A shock is required to have a range of adjustment that is an equal adjustment per click (almost like a flight of stairs) where the separation between the last adjustment is the same each and every step. This allows a tuner to make the proper adjustments to the shock after testing, and evaluation of the pass to predict the changes that each adjustment will make.
In comparison to a bias-ply slick car, radial tire cars require very specific changes on the compression side of the shock to help keep the tires applied, and to utilize the stiffer sidewall construction of the tire. This addresses the fact that a radial designed tire will have a greater tendency to rebound off the track during initial launch.
“You can also factor in the horsepower and torque, since the shock needs to be stiffer as the horsepower and torque output of the vehicle increases. That kind of works into the ‘secret sauce’ of the individual shocks and how they’re tuned,” Saffell stated.
The piston is essentially just a simple two-way valve that utilizes a shim stack — a series of washers in various thickness that acts as a spring against the shock fluid. This is what controls the main valving of a shock and allows manufacturers the ability to control the pressure differentials as the shock functions.
When building certain valve codes that are subjected to aggressive rebound and compression dampening, we may need to run greater nitrogen pressures. – Mark Menscer, Menscer Motorsports
“Nitrogen pressure is also dependent on your valve code set-up,” said Mark Menscer of Menscer Motorsports. “When building certain valve codes that are subjected to aggressive rebound and compression dampening, we may need to run greater nitrogen pressures. In retrospect, when the rebound and compression is less, we may not need to run as much pressure. Nitrogen is important in the construction and tuning of the shocks and is a very useful tool when setting up a radial tire car, but requires the suspension engine and shock adjustments to be dialed in around 100 percent. Typically, our nitrogen pressure runs from 50 to 100 psi depending on the application.
Menscer utilizes a bladder to isolate the nitrogen charge from the shock fluid in its external canisters. This is a different approach in comparison to other shock manufacturers that use a piston to separate the shock fluid. Menscer’s years of experience and development has determined that the bladder design allows for a smooth operation throughout the complete range of shock movement and fluid transfer. A floating piston-designed external canister may be prone to stick and make drastic bounces as enough pressure builds up to overcome the sticking piston, whereas expanding bladder eliminates this hazard.
Any minute adjustments made with the help of a set of fluid bleeds inside the shock valve body. The knobs on the exterior, or external canister of an adjustable shock, are directly connected to a needle-and-seat style bleed. Menscer also installs a one-way check valve in the shock to ensure that the compression and rebound control remain 100 percent independent from one another, allowing the end user to completely dial in their suspension to improve the adaptability of the shock.
Compression is controlled using this needle-and-seat design, allowing for subtle control over the rate at which the compression cycle displaces the fluid in the shock. A base valve also works in conjunction with the needle-and-seat acting as a bypass valve. When the shock transfers from low to high speed control, it operates much like the main piston of the body being controlled with similar set of shims
Rebound adjustment is achieved through a needle and seat located in the piston rod, which is gun-drilled. Adjustment of the exterior knob allows the fluid to bypass the entire piston assembly of the shock via weep holes in the upper portion of the piston rod, allowing for subtle changes in the way the tire is planted onto the track.
The diameter of the piston rod is also taken into account. Ideally, you want the smallest shaft diameter rod that can still retain structural integrity. All Menscer Motorsports shocks come with 5/8-inch diameter shafts, which is the ideal set-up. The larger the shaft, the more fluid it displaces, and as a result, the shock would be required to have a larger external canister. A shock with a large diameter shaft would also require a greater amount of nitrogen charge and shock fluid. The added fluid would, in turn, limit the control of the accelerating and decellerating dampening forces.
Menscer Motorsports and Afco Shocks have dedicated countless hours in testing in the drag racing world over the past eight years, and are clearly making an impact on the sport. Through combined efforts, an astonishing number of record-breaking passes are being recorded on tracks around the country.