Formula 1 car ride height is classified as the distance between the undercarriage of the chassis (the reference plane) to the ground. But F1 cars have a skid block or plank that rests below the reference plane and therefore ride height and ground clearance represent two different things.
Ride height is important because you don’t want the belly of the vehicle dragging the ground, but you do want to keep the centre of gravity low enough for maximum cornering. But, in the end, it is aerodynamics that determines the proper ride height.
Formula 1 car ride height
When a race car is experiencing an enormous amount of down-force, the ride height changes constantly. When the car goes fast, aerodynamic forces act on the vehicle in such a way that it is forced downward.
Therefore, the actual ride height is governed by the aerodynamics forces working against the vehicle at any given time. Simply put, the ideal ride height depends on the speed of the vehicle. So, the challenge facing the race car engineer is to set the ride height as close to ideal as possible for all conditions.
The static ride height can be modified by extending the length of the suspension’s pushrods using spacers, or shims. Normally, the suspension rods are only extended by a half millimetre at a time. The typical Formula 1 car runs with a static front ride height of 30 to 35 millimetres and a rear static ride height of 75 to 80 millimetres.
The dynamic ride height, on the other hand, is determined by the stiffness of the suspension spring (the stiffer the springs, the more resistant they are to downforce) and the tire pressure because increased tire pressure makes the tires more rigid. Stiffer springs and higher tire pressure work together to create greater dynamic ride heights.
But running the car as low as possible is not necessarily true for the whole car. The front end of the vehicle does need to be as low as possible, but the rear usually has a higher ground clearance. This allows the underbody aerodynamics to work better. The difference between the front and read ride heights is known as the rake. Ideally, the race car performs better with positive rake.
What causes uneven ride height?
The relation between ride height and aerodynamics is an intricate one. Racecar engineers use an aerodynamic map to show how downforce works against the aerodynamic contours of the vehicle in a variety of combinations to determine the optimum ride height. They then use their findings to set the vehicle’s rake accordingly.
If they fail to find the optimum downforce ratio between the front and rear of the vehicle, performance will suffer. If the downforce hits the car in a way that is not conducive to aerodynamic balance, it will affect steering, making the car hard to handle.
Active ride height differs from both static ride height and dynamic ride height in that its objective is to keep the ride height the same under all race conditions, yet with a suspension that is hardy enough to absorb any bumps in the track it may encounter.
When it senses an aerodynamic load influencing the body, like in downforce, the suspension automatically stiffens to accommodate the pressure. But when the wheels signal the approach of bumps in the roadway, the suspension relaxes. This multiple-personality characteristic of this suspension system gives the driver the best of both worlds in one.
The main purpose of the suspension is not to ensure a smooth ride, however, but to attach the vehicle to its wheels. This might sound like a small matter, but the process involves weaving together several different systems to safely move a heavy object like a race car down the track at tremendous speeds.
How does ride height affect handling?
On a regular automobile, the suspension system has two primary functions – manoeuvrability and ride. Here, ride refers to the way the car deals with different road conditions, how it handles bumps, potholes, curbs, and other changes in the road surface. The suspension absorbs energy created by the vehicle when driving over rough surfaces and dissipates it evenly between the four wheels. Handling, on the other hand, refers to how the vehicle reacts to commands from the driver, like during braking and turning.
Formula 1 suspensions perform the same tasks, although the criteria are slightly different. Take comfort for example. This is an important quality in regular automobiles, but not so much in Formula 1 racing.
Although ride and handling are the primary functions of both Formula 1 and road cars, Formula 1 cars are tasked with a third function – aerodynamics. Or more precisely, to use aerodynamics to create downforce. This is referred to in engineering parlance as platform control. Meaning, the faster the race car goes, the more downforce it creates.
When a race car is travelling at high speeds, the downforce it creates is several times greater than its body weight. Therefore, the Formula 1 suspension must be able to handle tons of extra weight when the car is speeding around the track. So engineers are faced with the huge challenge of making the suspension durable enough to take the extra weight and making it aerodynamic.
The position of the suspension relative to the track is extremely important for the aerodynamic concept to work. Raising or lowering the vehicle by a few millimetres can drastically change the airflow, reducing the effectiveness of aerodynamic parts like the diffuser. So, the engineer must ensure that the Formula 1 suspension rake and ride height be fine-tuned so that the vehicle’s aerodynamics can perform at its fullest potential.
Formula 1 suspension’s elements are also similar in concept to those of a regular automobile, so the springs on all four corners work independently. The elements that make up a Formula 1 car’s suspension can be put into three groups: inboard suspension, outboard suspension, and airflow. Obscured by the body of the Formula 1 car are the suspension’s inboard elements, springs, dampers, rockers, and anti-roll bars. The suspension’s inboard elements link to other elements in the airflow: pull rods, push rods, track rods, and wishbones. These elements are linked to the outboard elements which are tucked away behind the wheels – uptights, axels, and bearings.