The Complete Guide to Car and Truck Suspension Parts
Often overlooked, but one of the most crucial systems within a car or truck is suspension. The suspension is responsible for how effectively a vehicle responds to road obstacles, challenging road conditions and other hazards. On-road examples of this include but are not limited to: potholes, uneven pavement, banked turns and speed bumps. The suspension plays a critical role by softening blows caused by road dips and other bumps large and small; essentially leveling the vehicle allowing for easy handling and maneuverability.
Chassis and Frames
The suspension is made up of multiple car and truck suspension parts with the largest being the frame. The frame in a vehicles main purpose is to act as a load carrying, structural component. Mounted to the frame is the vehicles body, engine, and axle supported by another group of components; the control arms, springs, and shocks.
Rear Leaf Springs
Frames are designed not to flex or bend where as the springs and shocks absorb and dampen imperfect or uneven road conditions. Rear springs can be categorized into two major design styles: leaf springs and coil springs. Leaf springs are typically found on trucks and classic muscle cars. Easily recognizable by construction of four or five layers of individual leaves of steel bound together as a single unit. The leaf spring allows for congruent response without transferring from wheels to the chassis. Overtime, weight and stress put onto the system can cause sags, cracking, and breaking. Leaf springs can provide an excellent ride and they can support a lot of weight.
Front Coil Springs
The fist and most common type of spring is called a coil spring. Coil springs function exactly as a rear springs do in that it is supporting the weight of the vehicle and at the same time, being controlled by the shock absorber. Coil springs are widely used and the most common spring type found on cars and trucks. Coil springs can be hot wound or cold wound and are typically a heavy torsion bar coiled around an axis. This spring compresses and expands to absorb the motion of the road underneath. Springs support the weight of the vehicle and shocks control the coilsprings.
Torsion bars function by spreading the load over a large area to minimize chassis roll while driving in difficult or uneven terrain. No matter which spring is selected it is expected to have the aid of a shock absorber. In general this is a suspension style that regulates the actions of the springs, while also reducing the magnitude of vibrations in driving. Take for example the action required in traversing a speed bump. When hitting a bump with torsion bar suspension, the torsion bar will take the impact along with the spring. The torsion bar will then aid in returning the wheels back to their ride height position once the bump has been rolled over.
Whether you’re on-road or off-road, every spring needs a shock absorber. Shock absorbers are a device that regulates the actions of the springs, while also reducing the magnitude of vibrations in driving. Take for example the action required in taking a truck down a rutted dirt road. When the bumps are hit with the wheels, energy is transferred to the spring and the spring is controlled by the shock absorber.
Shock absorbers control the energy transferred through the spring and suspension. Every shock has a piston that travels within the shock body. The piston inside the shock with the piston shims, shock oil and nitrogen gas charge work together to control the force or rate at which the shock travels. This compression of the shock and transfer of fluid is what reacts to the suspension moving and controls the rate of speed in which the suspension travels as the vehicle moves down the road. A good set of shocks with the right springs are two of the largest factors in getting a smooth ride from your vehicle.
Coilovers are another type of shock that work in unison with coil springs. Commonly found in high performance vehicles, coilovers have two major functions. Coilover shocks allow for raising and lowering the vehicle’s stance by allowing one to adjust the pre-load of a coilspring. Adding more pre-load to the spring on a coilover will raise the vehicle. By reducing the spring pre-load, coilovers allow lowering. Aesthetically allowing for ride height adjustment for an improved look, and adding a lower center of gravity for better handling and control.
Select coilovers also offer a wide range of adjustment. Adjustable coilovers that allow shock tuning allow the user to set the rebound and compression settings of their coilovers for even better handling and shock response.
A third damping mechanism to assist the springs and shock absorbers is the suspension strut and anti-sway bars. Anti sway bars are metal bars that join opposing suspension systems in tandem.
Tires & Wheels
Lastly the tires and wheels are components that put the vehicle into motion. They are actually responsible for things like grip to the road and friction control. Tires and wheels are responsible for how a car will react in situations of over steer, under steer and bump steer.
Types of Suspension
Solid Axle Suspension
Dependent front suspension requires a large axle typically a beam axle, solid axle or four bar to connect wheels together and supported by a coil spring and shock absorber. This method is uncommon production cars and found in small amounts used by trucks.
More common is an Independent front suspension which allows wheels to move independent from each other connect by the steering system. As a result a number of solutions aim to tackle the problem. A double wishbone also referred to as an A-arm connects to the wheel to the frame with a coil spring and shock mounted in between the top and bottom of the arms, allowing for a greater steering consistency while minimizing sway. The other common solution is to use a transverse leaf spring with a wishbone. Functionally similar to a wishbone system but with a single leaf spring to replace the two coil springs.
Air suspension uses air bags instead of coil springs to support the vehicle. Airbags can also be added for additional weight support or to raise and lower a vehicle’s stance. Air bag suspension systems use an engine driven or electric air compressor pump to control flexible bellows that can provide a smooth, and constant ride feel, while controlling ride height on demand. Air bag suspensions also require shocks or adjustable shocks to further control the ride quality of the air bag system.
Suspension plays a critical role in how your vehicle handles and how smooth your car or truck will ride. Whether you’re looking for a type of look or stance, or looking to improve your handling or traction; suspension is one of the key elements in getting your ride down the road.
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