Anyone who has watched Formula 1 has seen the black rods connecting each wheel to the chassis of the car. You might know that those rods make up the suspension, but how exactly do they work? Although it uses the same principles, F1 suspension looks very different from conventional suspension.
F1 suspension uses springs (torsion bars) and dampers to maximize the mechanical grip of the tires even when the car is going over kerbs or through corners. The suspension also has a significant effect on the aerodynamic performance of the car by affecting the attitude of the car.
So how does the suspension accomplish all this? And what internal components are at work on the end of those rods that we can see? Below, we look at each element of F1 suspension in more detail to understand how it can be such a crucial part of the car’s overall performance.
How Does F1 Suspension Work?
When a car is driving along a road, the only points of contact that the car has with the road are the four tires. More specifically, only the contact patch of each of the four tires – that portion of each tire that is physically touching the road. However, the road surface is not perfectly flat but has some unevenness in it.
Therefore, as the car moves forward and the tire encounters unevenness in the road surface, such as a bump, the tire will move upwards in relation to the main body of the car. The attachment of the tire to the main body of the car therefore needs to allow for some of this freedom of movement.
However, there also needs to be some stiffness in this attachment, or else the wheels will move too freely, and the weight of the car body will simply cause it to rest on the road or the wheels themselves. This stiffness in the connection must ensure that the car body remains suspended above the road.
The most common form of this attachment arrangement is a spring. A spring will allow some freedom of movement up and down but also has enough inherent stiffness that the body will remain suspended from the wheels resting on the road surface. The ‘spring’s used in F1 are usually torsion bars.
A further element in the suspension arrangement is the damper or the shock absorber. When a tire moves relative to the body of the car, the spring can absorb that energy in the movement. However, a spring alone would simply release that energy immediately, causing an oscillating tire. It is necessary to use a damper to allow the spring to release that energy in a slow, controlled way.
The damper provides some resistance to movement – more specifically, resistance to fast movement, forcing the movement to be slower instead. This is typically achieved by a pneumatic or hydraulic cylinder, where the passage for air or hydraulic fluid to move is very small and thus limits how quickly the cylinder can compress or extend.
What Are The Different Parts Of An F1 Suspension?
The different parts of a Formula 1 suspension are:
- Pushrods or pullrods
- Torsion bars
- Anti-roll bars
- Heave springs
The finer mechanical details of the suspension of an F1 car are very different from that of a road car. There are a number of reasons, such as the different geometry of the vehicles and the available space, the priority on lower weight in F1, and the intensity of the conditions the suspension is subjected to.
A Formula 1 suspension arrangement comprises rockers, torsion bars, and dampers. For the following discussion, let’s consider a single suspension arrangement for a single wheel (so there will be four of these arrangements on a car).
The pushrod (or pullrod – to be discussed later) is the visible rod between the car body and the wheel, and this acts on a rocker within the car chassis to convert the vertical motion of the wheel into an angular motion within the car’s body.
The reason that this conversion to angular motion is done is because the “springs” that F1 cars use are actually torsion bars. These torsion bars are lighter and smaller than springs and therefore suit an F1 car much better. The way they absorb the energy of a wheel’s movement is by twisting. Yes, a bar of metal being twisting and untwisting again is F1’s version of a suspension spring!
This torsion bar is often a hollow tube and has external splines (like gear teeth) on each end. One end is held stationary (attached to the chassis), while the other end is mated to the rocker and is caused to rotate by the upward and downward movement of the wheel.
Now the rocker is not only connected to the pushrod (or pullrod) or the torsion bar but is also connected to the damper. The damper is a hydropneumatic cylinder that extends or compresses according to the movement of the rocker. A damper is designed to dissipate the energy of the torsion bar untwisting.
These hydropneumatic cylinders use a combination of hydraulic fluid and air to control how easily the damper can be compressed or extended. The damper provides a resistive force based on the change of velocity. Small passages for the hydraulic fluid to move through mean that a slow movement is easy to complete, but a very fast movement meets with significant resistance.
This can be tuned within a damper for how stiffly it will react to movements in the wheel – considering jolts such as going over a kerb, compared to the more gradual motion of the car pitching forward as the driver brakes for a corner.
A further element of F1 suspension (and most commercial vehicle suspension) is an anti-roll bar (or sway bar). This is a bar that connects the two wheels of an axle in such a way that the vertical motion of one wheel will induce a vertical motion in the other.
When the car is rolling onto the outer wheel through a corner, that wheel will want to move upwards in relation to the car’s body. However, through the anti-roll bar, that will cause the inner wheel to want to move upwards as well, counteracting the roll.
The anti-roll bar is also a torsion bar, which allows for some twisting and, therefore, some difference in displacement between the two wheels of the axle. This stiffness of the anti-roll bar is another element of control in the suspension setup of a car, affecting how susceptible a car is to roll in corners.
Another suspension element to limit the sudden movement of the car body (and therefore improve the aerodynamic performance) is the heave spring. Heave is when both wheels on an axle undergo the same force – either compressing or relaxing both suspensions. Heave occurs when the car pitches forward or backward, such as when the car is braking or accelerating heavily, respectively.
A heave spring is connected between the rockers of the two suspension arrangements on the axle. When those two suspension arrangements undergo the same effect (such as compressing at the front axle when braking), the heave spring resists the simultaneous compression, therefore counteracting the heave, or pitching. This helps to keep the car steady even during sudden massive changes of momentum.
KEY POINTS• F1 car suspension is made up of many of the same elements that go into road car suspension
• F1 cars use torsion bars instead of coiled springs to save weight
• All of the suspension components work together to control the car’s handling
Push Rod vs Pull Rod Suspension In F1
Modern F1 uses two arrangements of suspension – the pullrod and pushrod. The difference between these two arrangements is the relative position of the rocker in the car chassis compared to the wheel. If the rocker is placed low in the chassis, the upwards motion of the wheel (bumped off the road, for example, by a kerb) will pull the rocker around. This is a pullrod arrangement.
If the rocker is mounted high up within the chassis, the upward motion of the wheel will rather push the rocker around. This is, therefore, the pushrod arrangement. There are advantages and disadvantages to each arrangement.
The Issue Of Packaging
They have an impact on the ‘packaging’ of the components – how easily the various systems of the car fit within the regulated body dimensions, as well as the aerodynamic goals. Further to that, the positions of the push or pull rods between the body and the wheel influence the airflow and therefore have an effect on aerodynamics.
As an example, since Red Bull reintroduced pullrod suspension for the rear axle in 2009, it has been adopted throughout the paddock, as it provides significant advantages. The pullrod being lower provides less interference with the air flowing through the ‘coke bottle section’ at the rear of the car and joining up with the air exiting the diffuser.
QUICK FACT: Most F1 teams use push rod suspension at the front and pull rod at the back
For the front axle, generally pushrod is more common, but there are examples of both arrangements in use by different teams. The choice at the front axle has an impact on the airflow down the rest of the car body, so it is a fairly early decision in determining the ‘direction’ of the development of the car.
What Is The Purpose Of Suspension in F1?
Suspension is the mechanical connection between the body of the car and its four wheels. The suspension must allow some freedom of movement of the wheels as they travel over an uneven surface but must also ensure that the body of the car remains suspended off the road and generally have its movement relatively undisturbed.
The suspension is required to have limits on how far it can extend in order to limit the ‘bottoming out” of the car. The underbody of the car, its floor, and the diffuser are key pieces of the aerodynamics of the car, and they should be protected from damage from the track surface.
In another way, the purpose of the suspension can be seen as ensuring that each of the tires remains in good contact with the road despite disturbances. The suspension is a key part of maximizing the mechanical grip of the car by maximizing the tires’ contact with the road.
Attitude Of The Car
It is important to understand how an F1 car moves relative to its ‘neutral axis’ as it drives around a racetrack. The car’s ‘neutral axis’ is how it rests naturally while sitting still in the garage.
Now consider as it pulls out of the pits, and the car accelerates. The acceleration of the car, coupled with its inertia, moves the center of gravity of the car backward. This pitches the nose of the car slightly upwards, and the rear of the car sinks slightly.
The opposite is true when the driver brakes before heading into a corner – the nose pitches downward in relation to the rest of the car. The suspension of the front axle is compressed as the weight of the car moves towards the front. The suspension at the rear axle relaxes slightly.
As the car drives through the corner, the centrifugal forces push it towards the outside of the corner, causing some roll of the car. The roll is a sideways rotation of the car about its central axis, and it shifts the weight of the car more onto the outside tires, also rolling them over slightly and affecting the contact patch of the tires with the track surface.
The Yaw And Overview
A further aspect of how a car moves through a corner is the yaw. Yaw is the difference between the direction the car is moving compared to the direction the nose is pointing in. To illustrate, if the car has oversteer and the nose turns in too tightly to a corner, and the rear slides out slightly, the car is actually moving in a slightly different direction to where the nose is pointed.
QUICK FACT: Together, pitch, roll, and yaw make up the attitude of the car. The attitude affects the way that the car passes through the air around it, and as such, it affects the aerodynamic performance of the car.
The suspension arrangement prevents the car from bouncing around or changing attitude excessively through corners and over kerbs. The more cleanly and consistently the car can be presented to the air around it, the greater the downforce the aerodynamic elements can create.
One of the key elements of the aerodynamic downforce generated is the ride height of the car. This is due to the ground effect aerodynamics reintroduced in 2022, which accelerate air underneath the car, creating a low-pressure area that sucks the car to the track. Essentially the car body is used as an upside-down wing.
The effectiveness of this low-pressure zone depends heavily on being able to keep the airflow underneath the car separate from the airflow around the car. When ground effect aerodynamics were first developed in the late 1970s, skirts were installed along the sides of the car to keep a seal with the road surface.
In the regulations from the 2022 season onwards, which allow significant ground effect aerodynamics for the first time since 1982, no side skirts are allowed. As a result, the ride height of the car’s floor above the road surface has a meaningful impact on how well the air under the car and the air next to the car can be kept separate.
The suspension setup has a key influence on maintaining this ride height at an optimum throughout the car’s lap around the circuit. Braking, cornering, and driving over kerbs all affect the ride height of the car as forces are exerted on different parts of the chassis and tires. The suspension attempts to minimize this movement while still maximizing the mechanical grip of the tires.
Porpoising And Suspension
This low ride height introduces issues of its own. When the underbody downforce is maximized (such as on high-speed straights), the low-pressure area sucks the car down onto the road. This reduces the gap between the track surface and the bottom of the car until the airflow stalls – it can no longer easily flow through the small gap. In extreme cases, the bottom of the car strikes the track.
The stalling airflow results in an immediate drop of downforce and a loss of that low-pressure suction. The car then rebounds back to its neutral position, with a larger gap between the track surface and the car’s underbody. This allows optimum airflow to form once again, generating the low-pressure area again (and the resulting downforce).
The car gets sucked downwards, the airflow stalls, and the cycle repeats itself. This cycle is called porpoising, as it can be easily seen by the car’s nose alternately diving and rising like a dolphin swimming through the water.
Effects Of Porpoising
However, in the cars of the 2022 regulations, the high frequency of the porpoising coupled with the force of striking the track each time results in a very uncomfortable ride for the driver, and their heads can be seen bouncing up and down. That is in addition to the aerodynamic losses that porpoising causes.
The current passive suspension arrangement of F1 cars is unable to compensate sufficiently for the porpoising issue while still maximizing performance throughout the rest of the lap. The suspension setup for optimum lap time still prioritizes mechanical grip in the tires and a more stable chassis while cornering – these benefits outweigh the time lost due to porpoising on the straights.
In order to fix the porpoising issue with suspension, without raising the ride height, an active suspension that can adjust in real-time around a track layout would need to be used.
Such an active suspension (explained in more detail further on) could ensure a minimum ride height is kept even at peak underfloor downforce along the straights. It is unlikely that F1 will allow active suspension as a solution to porpoising.
KEY POINTS• F1 suspension keeps the car’s ride height stable when racing
• Pitch, yaw and roll are all affected and to an extent controlled by the car’s suspension
• Porpoising is an issue caused by low ride heights combined with the ground effect
• Active suspension could present a solution to porpoising
How Is F1 Suspension Made?
F1 suspension is made of multiple materials, including carbon fiber, steel alloys, aluminum alloys, and titanium, each with its own level of complexity. They’re put together by specialist mechanics that have the knowledge to be able to assemble it. Shims also get added to make minor adjustments.
As explained, F1 suspension is made up of multiple components, and each of these has some of its own inherent complexity. These components need to be incredibly strong to withstand the extreme forces that a Formula 1 car undergoes while still being as light as possible. As a result, they are manufactured of materials such as carbon fiber, steel alloys, aluminum alloys, and titanium.
The pullrods/pushrods, wishbones and track rods (steering arms) are the elements between the wheels, and the car’s chassis. All of it sits within the airflow and are therefore made of carbon fiber and specifically designed to be a coherent part of the aerodynamics. Some of the rods are hollow to save weight but also to allow sensor wires and tire tethers to pass through them to the wheel hubs.
The inboard components (those housed within the chassis of the car) such as the rockers, torsion bars, and dampers are generally manufactured of metallic materials.
The assembly of all of these components into the complex suspension system is done by specialist mechanics within each F1 team. Some of the components need to be easily switched in order to adjust the suspension setup for a race. For instance, torsion bars of different lengths or stiffness can be switched out to adjust the stiffness of the suspension.
Shims (thin strips or wedges of specific thickness) are also added or removed to make minor adjustments, such as to the neutral ride height of the car. The swapping out of components is done in the pits, during or between practice sessions leading up to a Grand Prix, in order to achieve the best setup for the race.
KEY POINTS• F1 suspension is made up of lightweight but very strong materials
• The suspension is made up of both inboard and outboard components
• F1 car suspension is highly adjustable
Interesting Suspension Arrangements
F1 would not be the sport we know and love if there weren’t some engineers trying to push the boundaries on what is acceptable within the rules. Suspension is no exception, especially since it has such an effect on the rest of the car’s performance. As a result, there have been some interesting suspension arrangements that have been run on F1 cars over the years.
Active suspension was a key feature of the dominant Williams FW15C in 1993. Active suspension included all the elements of traditional passive suspension but added servo motors, adjustable dampers, and electronic sensors. The car gathered information from the sensors and fed that through a control unit to actuate the servo motors to adjust the suspension and overall ride height.
In this way, the suspension was ‘active’ – the electronics allowed the suspension to actively respond to the conditions it was undergoing. Therefore, when driving through a high-speed corner, the suspension of the two outer wheels could adjust to be stiffer, reducing the roll of the car and keeping the aerodynamics closer to their ideal airflow.
Since the suspension could actively and autonomously adjust throughout the race, at every corner, and on every straight, the car’s aerodynamic performance (and mechanical grip) was maximized throughout the lap.
Active suspension was, however, banned from the 1994 season onwards. This was mainly due to a move in the sport to limit electronic driver aids as it was felt that they were reducing the influence of the driver’s skill and experience on the results of the car.
Tuned Mass Dampers
Even though active suspension was no longer allowed, the Formula 1 teams continued to look for ways to improve the performance of the car throughout a lap by doing something clever. Tuned mass dampers were introduced by the Renault F1 team in 2005 and run again for a portion of the 2006 season. Renault won the constructors’ championship in both those years.
A tuned mass damper is a moveable mass that sits within the body of the car and moves in the opposite direction to the movement of the car in order to counteract it. Tuned mass dampers are technically not part of the suspension of the car but rather a separate component. However, they have a direct influence on the pitch of the car when braking and accelerating.
The movement of the mass damper can be tuned to react to certain frequencies of movement or oscillations – those that can have the most effect on reducing aerodynamic performance or mechanical grip. When the car would go over a bump or a kerb, the tuned mass damper would pull the nose downwards, keeping up high levels of grip and downforce through the corner.
Although F1 allowed Renault to run the system in 2005, the number of teams developing a solution in 2006 made it clear that there was an aerodynamic advantage to the system. As a result, F1 outlawed tuned mass dampers as they were classified as “moveable aerodynamic devices.”
Another innovation almost a decade later (in 2014) was FRICS – Front Rear InterConnected Suspension. The concept with this arrangement was that the suspension of the two axles, front and rear, were connected through hydraulic fluid to keep the car more stable.
As an example, under braking, the front suspension would compress as the car pitched forward. This would create high pressure in the hydraulic fluid, which would transfer that to the rear axle, where the suspension would also compress as a result. This would minimize the pitching of the car, keeping it more stable and allowing a higher aerodynamic efficiency.
However, if the front and rear axles were connected in order to correct for pitch, then other connections could reduce roll. This prompted complex arrangements of hydraulic fluid connections between individual wheels, all connected by complex mechanical hydraulic valve arrangements. These would allow compensation of roll and yaw through corners and could be adjusted for each track.
The hydraulic components became increasingly complex, and F1 then banned the system. They were deemed to have too great an effect on the aerodynamics of the car, and outlawing them also saved cost and weight.
KEY POINTS• F1 suspension systems have evolved a lot over the years
• It’s a key area of the car where lots of competitive advantages can be gained
• The FIA usually bans such innovations if they are deemed driver aids or too expensive
The suspension of an F1 car works via a complex system of torsion bars and dampers designed to keep the car’s ride height stable. It is made of many different components, composed of materials like carbon fiber, titanium, and steel, and it is highly tunable to suit specific tracks and drivers.