Road racers talk about camber gain, roll center, and Ackerman. Drag racers talk about instant center, anti-squat, and pinion angle. Although these are all important factors in maximizing lateral and straight-line grip, optimizing suspension geometry is only half the battle. Unless a chassis can transfer weight—from side to side and front to back—in a controlled and predictable manner, all the effort put forth to optimize geometry could very well go to waste. That’s where a set of high-performance shocks enters the equation. By making the loading and unloading forces placed upon the tires as gradual as possible, shocks very much determine how effectively the rest of the suspension performs. For hot rodders, performance shock options abound, but which is right for your application and what’s the truth behind all the fancy terminology the message board crowd loves throwing around? To find out, we asked Chris King of Viking Performance to explain it all.
Although Viking is a relatively young company, founders Chris and Christina King have over 40 years of collective experience in the aftermarket suspension industry. When they started the company in 2011, they recognized a huge shortfall in the number of affordable double-adjustable shock absorbers in the market. As such, most hot rodders ran non-adjustable or single-adjustable shocks, and Viking’s mission was to make double-adjustable shocks attainable for all enthusiasts. By only focusing on double-adjustable shock absorbers, Viking is able to offer high-quality, double-adjustable shock at a similar price point to a typical single-adjustable shock. To complement its shocks, Viking has engineered its own line of springs and rod ends as well. One of Viking’s most exciting new products is its Berserker active suspension system, which utilizes powerful processors and a series of sensors to automatically adjust shock valving up to 1,000 times per second. Supercar technology previously reserved for Ferraris and Lamborghinis is now available for your muscle car. Shock technology has certainly progressed rapidly in recent years, so let’s dig in to learn more. Here’s what Chris King had to say.
What Shocks Do“Shocks are definitely the key to a car’s overall suspension performance. Some link shock absorbers to the brains of the suspension system. However, at Viking we consider the shock absorber as the heart of the suspension, as both utilize fluid flow to optimize performance. The function of the shock absorber is to absorb and dissipate energy. In terms of overall vehicle dynamics, the role of the damper is seldom fully understood. Vehicle dynamics engineers often talk about the personality of a car and spend countless hours tweaking the damping curve to get just the right feel, which is often different depending on where and how the car is going to be utilized. For example, the tune for Europe is much stiffer and biased towards performance than the American tune, which has historically been all about comfort in a straight line. Body roll angle in a corner is determined statically by a combination of the spring rates and the antiroll bar. For a given cornering acceleration, the body rolls until the roll stiffness multiplied by the roll angle equals the cornering acceleration multiplied by the roll moment arm. The damper cannot affect the eventual roll angle, since damper force is a function of relative velocity, not relative displacement. However, it can control how the body gets to its eventual roll angle. In general, low roll damping feels alarming because the roll rate is high, and there is usually some overshoot and oscillation. A well-damped vehicle feels very progressive and the vehicle will stabilize at its roll angle more quickly, which adds to the driver’s confidence. This also results in more constant tire patch contact force, which in terms of vehicle dynamics is the dampers main job. Tires produce a traction force, which is roughly proportional to the contact force up to the limit of adhesion. If this force is varying wildly during the entry into a corner, the steering balance of the vehicle will also vary, which is extremely upsetting to the driver’s confidence. The same can be said in pitch during hard acceleration and braking, so at the end of the day the dampers real value is that it keeps the tire on the ground and the normal force as constant as possible.”
Twin- vs. Mono-tube“There are definite benefits to both twin-tube and mono-tube shock designs and there are some high-quality shocks in the marketplace of both designs. Many races and championships have been won over the years with each design. However, for Viking’s target market we strongly feel that the twin-tube provides much more flexibility, benefits, and a higher value than the mono-tube design. In our opinion, the twin-tube flat-out performs better in drag racing, street performance, road racing, autocrossing, and just plain old cruising. Mono-tube shocks, by design, have rod force at all times due to being gas pressurized. Twin-tube shocks are unencumbered by rod forces since they utilize a gas bag instead of gas pressure. A vehicle operating on dry, slick asphalt surfaces will respond better utilizing a shock absorber that does not have the unwanted rod forces from the gas pressure in a mono-tube shock absorber. The twin-tube design will maximize tire contact. If you look at a basic setup for a street application, ride quality is going to be optimized by having a softer compression setting. This allows the suspension to absorb the bumps without knocking your teeth out, while also utilizing firmer rebound settings to keep the car from continually oscillating down the road. This is even more prominent in the front end of a car where you are dealing with the motion ratio of an independent suspension, and therefore fighting a higher spring rate. A standard mono-tube shock has the opposite effect of what you want the shock absorber to do, as you have now added rod force, which is like increasing spring rate. This adds compression forces, which require even larger rebound forces to control the energy and return the vehicle to ride height in a timely manner.
“In contrast, off-road trucks or dirt circle track racers may prefer the gas pressure of a mono-tube shock absorber to assist in keeping the vehicle from planting the tire into the rough surface. There are ways to decrease rod pressure in a mono-tube shock, such as through the addition of a base valve. However, this is where value comes into play, as features such as these drive the cost of the mono-tube shock much higher. Furthermore, twin-tube shocks allow fitting a longer piston rod, which nets increased stroke in a twin-tube shock absorber within the same shock body envelope. This is due to the gas chamber required in the mono-tube design that is not necessary in the twin-tube.”
Double-adjustable Advantage“The twin-tube shock design also fits in very nicely with our goals when we started Viking. We saw a huge shortfall in the number of double-adjustable shocks being utilized in certain markets, mainly due to substantial price premiums for these types of shock absorbers. We felt the majority of the market was unable to optimize the shock settings on their vehicles, and were stuck with overall ride quality and handling that was far from great. To get the best in performance and ride quality, the compression and rebound valving must be independently tuned with a double-adjustable shock. At Viking, in order to provide the highest value double-adjustable shock absorber, there was no other option except a twin-tube design. This design allows access to both the compression and rebound circuits in the base of the body. In contrast, on a standard mono-tube shock, the gas pressure resides in the base of the body. As a result, when adding adjustability to a mono-tube shock, these shocks are generally only rebound adjustable via a gun-drilled piston rod, which is very expensive. In order to access the compression side independently of rebound, a canister is added, resulting not only in mounting issues, but significant cost increases. For us, easy access to both compression and rebound adjustments is one of the main benefits of the twin-tube over the mono-tube. Another huge benefit of the twin-tube is the large adjustment range in the shock absorber. When adjusting via a gun-drilled piston rod, the pre-determined range is much smaller than the range provided in the twin-tube design. Further, the end user must understand and define the adjustment range prior to ordering the mono-tube shock, since the window of adjustability is so much smaller.”
Valving“Drag cars, road racers, and street cars all have different needs in terms of shock valving. However, it does not stop there. Driver style and capability, track and road conditions, vehicle type, vehicle weight, horsepower, and tires all create different needs in terms of shock valving.
“It is extremely difficult to provide the exact ideal compression and rebound shock settings for a given vehicle and driver on any given day. However, Viking does provide a very good place to start. That is the ultimate beauty of having a double-adjustable shock, as you are able to tune for your specific needs. For drag racing, the racer needs to understand how he wants the car to react. Based on all the factors already mentioned, does the racer want to maximize weight transfer? If so, the front will be set with a stiffer compression and soft rebound, while the rear will have a soft compression and stiffer rebound. If the racer wants to limit weight transfer, the setting will go in the opposite direction.
“The same variables above will come into play for road racing. It is easier to narrow the range of adjustment for road racing versus a drag race setup, but various factors will still need to be considered, as the rear settings on a pickup truck will vary quite a bit from an early A-body.
“For street cars, the settings get easier yet to define. Ride quality is optimized by having a softer compression setting in order to allow the suspension to absorb the bumps without knocking your teeth out, and it’s matched with a firmer rebound setting to keep the car from continually oscillating down the road. This is even more prominent in the front end, where you are dealing with the motion ratio of an independent suspension and therefore fighting a higher spring rate.”
Compression vs. Rebound“The compression side of the shock valving controls the force required to push the rod into the shock absorber. On a car, this equates to how it feels when you hit a bump, pothole, or other rough terrain in the road. A softer compression setting will allow the car to have more suspension movement and to come down in the front or squat in the rear. Too soft of a setting may cause the vehicle to easily bottom out. This will result in a higher roll rate, which may cause the driver to feel less confident. Too stiff of a setting will result in a jaw-jarring feeling when going over bumps. It will also result in a less than ideal tire patch contact.
“In contrast, the rebound valving controls how quickly the shock extends after being compressed. A higher spring rate will cause the shock to extend quicker, as there is more stored energy, thereby requiring a higher rebound setting. The softer the rebound setting, the more the car will oscillate before returning to the vehicle’s natural ride height. A stiffer rebound setting will result in the vehicle slowly returning to ride height. Again, too soft of a setting will result in a higher roll rate, which may cause the driver to feel less confident. Too stiff of a setting may cause the vehicle to ratchet itself down as it proceeds down the road, and the shock never allows the vehicle to return to normal ride height.”
Warrior Shocks“Viking’s shocks are available in either smooth body (non-coilover) or threaded body (coilover) for custom-mount or stock-mount applications. Stock-mount bolt-in shocks are available for all of the most popular Chevy applications. Even if you do not see your application listed, chances are good that we can build it. We also just completed our complete line of specifically designed shock absorbers for lowered and raised vehicles. A common mistake in the marketplace is lowering or raising a vehicle outside of a shock absorber’s operating range. A one-inch drop will not generally require a change in the shock absorber length. However, when you begin to lower the vehicle over 1.5 inches, the shock ride height should be analyzed to verify that it will operate effectively for that given vehicle stance. Viking has taken the guesswork out of the equation, as we have a product line by application to specifically handle these situations.
“The Warrior line was our first shock offering. These shock absorbers have a digressive force curve for both compression and rebound. This means that forces increase quickly at low shaft speeds and level off at higher shaft speeds. This valving provides excellent low-speed control with sufficient high-speed forces. Each adjustment knob (compression and rebound) provides for 19 positions of adjustment, providing a total of 361 valving combinations. Viking provides easy-to-read instructions with starting points depending on the application, making for easy setup and tuning. The valving adjustments are evenly spaced from click to click, and the shocks can be rebuilt or revalved by Viking or an authorized rebuilder. Other options are available, such as a solid piston to handle additional compression forces, and circulation of the oil through the outer body, thereby reducing heat. Warrior shock prices start at $169.95 each.”
Crusader Shocks“Based on requests from small tire, drag radial customers, Viking has developed a new line of patent-pending Crusader shocks. With these vehicles, there are situations that require rebound forces in excess of what standard passive adjustable shock absorbers can provide. These shock absorbers have the same digressive compression valving as the Warrior line. As such, there are 19 positions of evenly spaced adjustments. The rebound valving, however, is controlled by a progressive valve that is strictly determined via orifice control. A progressive valve shock will have a softer low speed force that ramps up very quickly as shaft speed increases. Do not let the definition fool you, as these shocks can generate huge forces at low speeds depending on the needle and seat combination. The rebound side has 22 available positions of adjustments. As a result, the Crusader line provides for 418 different valving combinations. Depending on the needle and seat combination, the adjustment range can cover a very large range or a more narrow range with very small, defined increments.
“A very cool feature of these patent-pending shock absorbers is their interchangeable needle and seat design. The rebound valving adjustment range can be changed without completely disassembling the shock absorber. With the shock laying on its side in the fully extended position, while clamped by a vise, the rebound knob can be taken off. After removing the needle with basic tools, the seat can be changed out with a flathead screwdriver. There are no expensive specialty tools required, and the process is similar to jetting a carburetor. We have found that any drag car with 750-plus horsepower can benefit from our Crusader series, no matter the tire size. We now have specific offerings out of the factory for various horsepower and tire combinations. In the coming months, we are going to be performing numerous additional tests in road racing, autocrossing, and general street applications, as we believe the potential of this shock design to be virtually unlimited. Racers can choose from a variety of progressive force ranges such as an extreme, high-force progressive valving—which is ideal for drag racing, road racing and other applications where high forces are required—or a soft valving for the ultimate in ride comfort. These units are only $75 more than our Warrior shocks.”
Application-Specific Kits“Viking offers bolt-in front coilover shocks and springs for the vast majority of Chevy applications. We offer easy-to- purchase kits, which provide the correct spring rate based on vehicle type, motor, and vehicle use. We have developed all-inclusive kits that include two aluminum double-adjustable coilover shock absorbers, two high-travel coilover springs, spanner wrenches, thrust bearings, and all mounting hardware. Everything you need is lumped into one part number, in one box, making it very simple to order everything correctly. To complement our front suspension coilover systems, we’re now offering a bolt-in, high-quality rear coilover system for the ’64-72 A-body, all G-bodies, third- and fourth-gen F-bodies, and select B-body applications. Viking has partnered with some of its very good U.S. fabrication customers to offer its high-quality rear coilover conversion bracket systems in these kits. When converting to a coilover system, you are placing the weight of the vehicle on mounts that were never designed for that purpose. Therefore, it is critical that the proper mounting brackets are utilized when converting to a coilover.”
Self-Adjusting Shocks“Viking’s Berserker Active Shock Management system is an all-new smart suspension management system that uses a suite of sensors and controllers to monitor wheel position, shock piston speed, and vehicle chassis acceleration to find the perfect damping rate for the conditions at hand. It is the only aftermarket system that monitors chassis inputs and reacts to them by automatically adjusting shock valving up to 1,000 times per second to accommodate driving style and road conditions. The Berserker ASM provides the ultimate in performance handling and ride control right out of the box. In addition, an optional upgrade allows advanced unlimited tuning, as well as suspension data acquisition for drag racing, autocross, road racing, or other applications via a laptop plug-in or a soon-to-be-released smartphone app. The patented Berserker ASM system was awarded Best Engineered New Product 2014 at the SEMA Show. It received two international media awards at SEMA for the same system.
“The Berserker ASM utilizes hydraulic shocks with computer-controlled, electrically actuated valving. This delivers ultra-high performance suspension control with improved ride quality without the need for the driver to adjust anything. The Berserker ASM includes a built-in technological bumpstop to prevent the shocks from topping or bottoming out, and automatically adjusts to absorb potholes, speed bumps, rough terrain, and wheelstands. In essence, it optimizes cornering, stopping, and launching to provide the ultimate in shock performance for autocross, road race, drag racing, or just plain old cruising. The system fits a variety of popular muscle car and hot rod vehicles, and it is also available in universal lengths and mounts. Depending on application, the shock controllers are either remote mounted for clearance around chassis and suspension components, or piggybacked onto the shock body.
“Each shock has its own controller, which maximizes performance for each individual corner. In addition, a master controller is mounted on the chassis and monitors and optimizes the complete suspension system in real time. The technology in the Berserker ASM system monitors a wide range of chassis inputs including yaw rate, suspension position, acceleration/deceleration, and steering position. Systems are available to install Berserker ASM technology at all four corners of your vehicle, or at just the front or rear. The complete Berserker system retails at approximately $5,000.”
Active vs. Passive Suspension“A good passive suspension can be tuned for a particular application at a particular weight for a particular driver’s preference, but if you change any of those constraints it is no longer ideal and the passive shock must be tuned manually. The goal of semi-active dampers is to eliminate that compromise to the greatest degree possible. Think of it as being able to turn the knob to adjust rebound or compression in real time while the vehicle is traveling down the road, but much faster than humanly possible at 1,000 times per second. Unlike passive dampers that work on a single damping curve, Berserker ASM shocks work in a damping area with a very low minimum damping for ride comfort and much higher forces for handling maneuvers. The controller at each corner of the vehicle senses the conditions and changes the electronic damping valve within 10 milliseconds to prevent the suspension from bottoming- or topping out. The master controller mounted to the frame uses accelerometer data from the corner controllers to sense where the energy is stored in the system, determine whether the vehicle is in heave, pitch, or roll and sends out commands to the shocks to change damping force to manage the chassis movement.
“Information on steering position is fed to the master controller, allowing the system to control body roll during handling events by stiffening the shocks in compression on the outside wheels and rebound on the inside wheels. This acts as a virtual sway bar by providing excellent turn-in on corner entry. The result is a vehicle that provides superior ride quality and razor sharp handling without compromising either. The best news about the ASM is it is available as an option on our entire shock lineup. It can be added to any of our shock configurations, which makes fitting the latest cutting-edge technology to your street machine or Pro Touring muscle car a reality. We will initially be offering the system as a full vehicle package, and we are also working on a rear system specific to drag racing applications.”