Suspension in F1 Cars

The suspension system in an F1 car, while fundamentally similar to that of a road car, is designed without regard for comfort. It is extremely stiff, moving only a few millimeters, and is critical for safety, as structural failures can have serious consequences. The suspension connects the car to its wheels and the track, handling all major mechanical forces from acceleration, braking, and cornering, as well as aerodynamic forces from downforce and drag. Therefore, it must be both strong and lightweight.

In contrast to other motorsport disciplines where suspension plays a more significant role in performance, F1's suspension has two primary functions: providing a stable aerodynamic platform by minimizing disturbances and ensuring that the tires operate at optimum efficiency.

A key feature of F1 suspension is the use of inboard springs and dampers, which are mounted on the chassis or gearbox. Springs give the suspension its stiffness, resisting vertical wheel movement, while dampers (often confused with shock absorbers) control spring oscillations, crucial for maintaining tire grip and handling.

Minimizing "unsprung mass"—the weight of components not supported by the suspension springs—is vital. This includes wishbones, push/pull rods, steering arms, and wheels. Reducing unsprung mass lessens the suspension's reaction to track imperfections, maximizing tire contact with the surface, which enhances grip and stability.

The suspension also absorbs weight transfer effects during acceleration, braking, and cornering, helping to maintain consistent tire temperatures and reduce wear. Key design factors affecting handling include wheelbase and track width. A longer wheelbase generally offers more stability, while a shorter one increases agility, though at the cost of stability. A wider track reduces lateral weight transfer.

The suspension system comprises four main components:

1. Linkages: Connect suspension parts and link wheels to the chassis. Key components include wishbones, push/pull rods, and anti-roll bars.

2. Joints: Allow movement within the suspension. Rose joints are commonly used, providing adjustability and mobility.

3. Springs: Resist vertical movement of the wheels.

4. Dampers: Control oscillations of the springs.

Each component's design is crucial for the overall performance of the suspension system.

The Car in Motion

A car moves in "six degrees of freedom" around three axes: vertical, longitudinal, and lateral. Understanding these motions helps to comprehend how various forces affect a car's performance, handling, and suspension. The six degrees of freedom relevant to a car are:

1. Roll: The rolling motion around the longitudinal axis, such as when the car leans during cornering.

2. Pitch: The pitching motion around the lateral axis, like when the front of the car dips during braking.

3. Yaw: The yawing motion around the vertical axis, occurring when the car slides during cornering or spins.

4. Heave: The vertical movement parallel to the vertical axis, such as bouncing over bumps or curbs.

5. Sway: The horizontal movement parallel to the lateral axis, often due to centrifugal force in corners.

6. Surge: The lateral movement parallel to the longitudinal axis during acceleration or braking; this term is less commonly used in motorsport.

In F1, the suspension primarily addresses roll, pitch, yaw, and heave. These motions must be considered when designing suspension geometry and setting it up for specific track conditions.

Suspension Geometry and Adjustment

Suspension geometry significantly affects a car's handling, stability, and overall performance. Designing the suspension involves complex mathematical calculations and simulations, but once the car is built, fine adjustments are still necessary for optimal setup. 

There are seven fundamental parameters for suspension adjustments:

1. Camber

2. Caster

3. Toe

4. Ride Height

5. Anti-Roll-Bar Stiffness

6. Spring Rate

7. Damper Adjustment

Adjusting one parameter often influences others, so changes should be made carefully and in small increments. While caster, camber, and toe angles can be fine-tuned based on wet or dry conditions and driver preference, the primary adjustments focus on anti-roll bars for mechanical balance and ride height via push- and pull-rods for aerodynamic setup.

Camber

Camber is measured as the angle between the vertical axis of the wheel/tyre tread and the vertical axis of the car when viewed from the front or rear. Positive camber tilts the wheels outward at the top, while negative camber tilts them inward. 

During cornering, the car rolls towards the outside, causing the top edge of the loaded outside wheel to roll outward, which can reduce the tire contact patch and grip. To counteract this, F1 cars typically use negative camber at the front wheels to maintain a larger contact patch and improve grip during cornering. 

This setup is exemplified by Lewis Hamilton's Mercedes W13, which featured noticeable negative camber during wet practice for the 2022 Emilia Romagna Grand Prix.

Suspension Geometry: Caster and Toe Settings

Caster Angle

The caster angle measures the angle between the steering axis and the vertical axis of the car when viewed from the side. A positive caster means the top of the steering axis leans rearward, while negative caster indicates it tilts forward. Positive caster enhances directional stability and provides the steering with a self-centering action, which is why modern F1 cars always use positive caster.

Adjustments to the caster angle are rare because they involve changing the mounting points of the wishbones or uprights, requiring significant modifications.

Toe Setting

The toe setting refers to the angle between the longitudinal axis of the car and the longitudinal centerline of the wheel/tyre tread when viewed from above. 

- Toe-in: Front edges of the wheels point towards each other.

- Toe-out: Front edges point away from each other.

F1 cars typically have toe-out at the front to improve cornering responsiveness and toe-in at the rear to counteract the tendency of the wheels to spread under load. Front toe-out can be adjusted by changing the track rod lengths, while rear toe-in adjustments are made by altering the toe link lengths.

Balancing the camber angle is crucial to maintaining grip during cornering while minimizing tire wear on straight sections. The goal is to achieve even tire temperatures across the tread, which is closely monitored.

For the rear wheels, a negative camber angle is common, but it is less pronounced than at the front. This adjustment ensures a larger contact patch for better traction during acceleration. In some cases, zero camber may be used at the rear for optimal traction when the car is not cornering.

Camber adjustments can be easily made using shims at the wishbone mountings to the uprights, allowing for precise tuning as part of the mechanical setup.

Ride Height and Anti-Roll Bar Adjustment

Ride Height

In F1, the front ride height is typically lower than the rear, creating a higher rake angle. The ride height measures the distance from the car's floor to the track, and the difference between front and rear heights is referred to as "rake." Recent trends show that teams like Red Bull Racing have adopted a more pronounced rake, which is a key setup parameter impacting aerodynamic performance. 

Maintaining a consistent ride height across all four corners is crucial, as even minor adjustments can significantly affect the car's aerodynamic efficiency. Ride height is usually adjusted using threaded links that modify the length of the push-rods or pull-rods.

Anti-Roll Bar Adjustment

The anti-roll bar (ARB) counteracts the tendency of the car to roll during cornering. Modern F1 cars typically use twin-rocker-type ARBs at both the front and rear. 

To alter the car's roll characteristics, the ARBs must be changed rather than simply adjusted. This adjustment is primarily aimed at improving the car's balance, influencing its tendency to understeer or oversteer. For example, to reduce understeer, one might decrease the stiffness of the front ARB or increase the stiffness of the rear ARB, and vice versa to address oversteer.

Vehicle Dynamics

While a comprehensive theory of vehicle dynamics is beyond this book's scope, understanding key parameters can illuminate the complexities of suspension design. Here are the critical factors that affect car performance and suspension design:

Centre of Gravity (C of G)

The centre of gravity is the central point where the total weight of the car's components is concentrated. For racing cars, the C of G is defined as a specific point in space, measured along the longitudinal axis and a specified height above the ground. Designers aim to keep the C of G as low as possible to enhance stability and handling.

Polar Moment of Inertia

In motorsport, the polar moment of inertia refers to the car's tendency to pivot around a vertical axis through its centre of gravity. A lower polar moment of inertia allows the car to spin more easily, but it also enables quicker response to the driver’s inputs. Designers strive to position heavier components, such as the power unit and driver, as close to the C of G as feasible to optimize this balance.

Centre of Pressure (C of P)

The centre of pressure is the point on the car where the sum of aerodynamic forces acts. For neutral handling, the C of P should ideally be close to the centre of the car, ensuring balanced aerodynamic effects during motion.

Roll Centre

Each car has separate roll centres for the front and rear suspension, which shift as the suspension moves. The roll centre is the point in the transverse plane between the tyre contact patches, around which the chassis rotates when subjected to forces, such as during cornering. This movement influences the car’s stability and handling characteristics. 

Understanding these parameters helps designers create more effective suspension systems, enhancing performance and handling in various racing conditions.

Key Concepts in Vehicle Dynamics

Weight Transfer

Weight transfer refers to how the load on the tyres shifts during different driving conditions, such as braking, acceleration, and cornering. When a car brakes, it pitches forward, causing weight to transfer from the rear to the front tyres. This can lead to wheel lock-up, as seen with Lance Stroll’s RP19 at the 2019 Japanese Grand Prix. Conversely, during acceleration, weight shifts from the front to the rear. In cornering, weight transfers from the inside tyres to the outside tyres, affecting grip and handling.

Roll Centre and Roll Axis

The roll centre is a point in the transverse plane of the car, influenced by the angles of the suspension wishbones. As the car corners, centrifugal force acts through the centre of gravity, causing the vehicle to rotate around the roll centre. The roll axis is the imaginary line connecting the front and rear roll centres, and the position of these centres can change with suspension load.

Roll Stiffness

Roll stiffness is the resistance of the car's sprung mass (the weight supported by the suspension springs) to rolling about the roll axis. Each car has separate roll stiffness for the front and rear, which can be adjusted through the anti-roll bars. Increased roll stiffness raises the load on the outside tyre during cornering, enhancing grip, while reduced stiffness has the opposite effect.

Weight Distribution

Weight distribution refers to how the car's weight is distributed between the front and rear axles. An F1 car typically has a rear-biased weight distribution, often around 45% front and 55% rear. This affects the centre of gravity, which shifts toward the axle carrying more weight, influencing handling and stability.

Tyre Slip Angle

The tyre slip angle is crucial for generating grip. It is the angle between the car's longitudinal axis and the direction the tyre is pointing. As a tyre deforms during cornering, this slip angle produces cornering force. Excessive slip angles can lead to sliding or drifting, which is not the same as normal grip operation.

Understanding these dynamics is essential for optimizing performance and handling in high-speed racing conditions.

Anti-Dive and Anti-Squat

Anti-Dive:

Anti-dive geometry is designed to counteract the tendency of a car's front end to "dive" toward the track during braking or deceleration. When the car slows down, it rotates around its center of gravity, causing the front to drop and the rear to lift. Anti-dive is achieved by angling the front upper and lower wishbones away from each other at their front ends, which helps maintain stability and prevents excessive forward pitch.

Anti-Squat:

Conversely, anti-squat geometry resists the rear of the car from "squatting" under acceleration. During acceleration, the rear of the car tends to drop, which can negatively affect handling and traction. Anti-squat is implemented by angling the rear upper and lower wishbones away from each other at their rear ends. 

Both anti-dive and anti-squat are integral to the car's suspension design and cannot be adjusted post-manufacture. Designers must consider the front-to-rear brake bias, as it influences force distribution during braking.

Suspension Layout

F1 suspension design is a balance of several factors:

- Aerodynamics: The optimal location of suspension components must minimize airflow disruption and potentially enhance aerodynamic performance.

- Stiffness Requirements: The suspension must be stiff enough to support the car's weight and manage dynamic forces.

- Control of Wheel Motion: Proper design ensures that wheels maintain optimal contact with the track.

Each corner of an F1 car typically features up to six structural suspension members: upper and lower wishbones (counting as four), along with push-rods or pull-rods for the springs and dampers, plus steering arms at the front and toe links at the rear. 

To enhance aerodynamic performance, teams often fit carbon aerodynamic shrouds over suspension components to minimize airflow disruption or manage airflow beneficially.

Multi-Link Suspension

Recently, some teams, notably Red Bull Racing, have adopted multi-link suspension designs. For example, the 2019 RB15 utilized a multi-link setup at the front, featuring upper wishbone arms connected to separate mountings on the upright. This configuration allows for greater tuning and flexibility compared to traditional double wishbone layouts, improving handling and performance characteristics.

Front Suspension Configuration

The standard configuration for an F1 car's front suspension is typically a double wishbone layout, featuring inboard torsion-bar springs, dampers, and an anti-roll bar. This system is usually activated by push-rods or pull-rods connected to the upright.

Key Components:

- Push-Rods/Pull-Rods: These connect the springs and dampers to the wishbones, with each positioned between the forward and rear legs of the wishbones. The push-rod is usually inclined, connecting the bottom of the upright to a rocker mounted high on the chassis. The pull-rod runs closer to horizontal, connecting the top of the upright to a rocker mounted lower on the chassis.

- Track Rod: Positioned between the upper and lower wishbones, this rod connects to the steering rack at the outboard end and the upper wishbone at the inboard end.

Advantages of Pull-Rod vs. Push-Rod

- Pull-Rod Advantages:

  - Aerodynamics: The near-horizontal angle of the pull-rod minimizes disruption to airflow from the front wing to the floor and sidepods.

  - Lower Center of Gravity: Components can be mounted lower on the chassis, which contributes to improved handling dynamics.

- Pull-Rod Disadvantages:

  - Strength Requirements: A pull-rod setup necessitates stronger (and often heavier) upper wishbones and additional reinforcement for the upper wishbone mountings on the chassis since it does not bear a portion of the suspension load as effectively as a push-rod setup.

Trends in F1 Suspension

While most teams traditionally favor push-rod configurations for the front suspension, the 2022 FIA regulations prompted some teams, like McLaren and Red Bull Racing, to adopt pull-rod setups again, highlighting the evolving nature of suspension design in response to regulatory changes.

Rear Suspension Configuration

The rear suspension layout in an F1 car is generally similar to the front, incorporating upper and lower wishbones, inboard torsion-bar springs, dampers, and an anti-roll bar. However, instead of a track rod, a toe link is used to control the toe setting.

Key Components:

- Toe Link: Positioned behind the wishbones, this component connects the gearbox casing (or rear crash structure) to the upright, allowing precise adjustments to the toe angle.

Push-Rod vs. Pull-Rod Rear Suspension

- Historical Context: Until 2009, push-rod rear suspension was standard for about a decade. Adrian Newey's innovative design on the Red Bull RB5 introduced pull-rod rear suspension, which quickly became popular.

- Advantages of Pull-Rod Layout:

  - Lower Packaging: The major components (springs, dampers, and rockers) can be positioned lower on the car, near the bottom of the gearbox casing, aiding overall packaging.

  - Lower Center of Gravity: This setup contributes to improved handling dynamics.

  - Aerodynamic Benefits: The positioning reduces disruption to airflow, particularly around the rear wing and the newly introduced underbody venturis.

Recent Trends

Although the pull-rod configuration dominated since 2012, for the 2022 season, both McLaren and Red Bull Racing reverted to a push-rod rear suspension layout. This change likely aimed to optimize aerodynamic packaging tailored to their specific design solutions, reflecting the ongoing evolution in F1 suspension strategies.

Aerodynamic Considerations

Aerodynamic shrouds have been extensively used on both front and rear suspension components to minimize airflow disruption, particularly important at the rear of the car where airflow affects the performance of the rear wing.

Suspension Compromises for Aerodynamic Gain

In modern F1 racing, aerodynamic performance has become the paramount factor influencing overall car performance. As a result, teams often compromise on ideal suspension designs to achieve better aerodynamic outcomes, particularly at the rear of the car where pull-rod suspension configurations are frequently employed.

Red Bull Racing RB6

A notable example of this approach occurred during the 2010 season with the Red Bull Racing RB6. The team designed the car to incorporate a double diffuser, which required significant modifications to the suspension layout:

- Lower Wishbone Positioning: To maximize the size of the diffuser tunnels, the lower wishbone was positioned further forward and higher than conventional designs. 

- Structural Compromise: This adjustment compromised the ideal spacing between the upper and lower wishbones, essential for maintaining suspension stiffness. As the rear leg of the lower wishbone was swept forward, it became heavier to ensure adequate structural strength.

- Trade-offs: Despite the drop in stiffness, the aerodynamic gains from the diffuser were deemed worthwhile, showcasing how structural integrity can be sacrificed for performance enhancements.

Evolution of Design Practices

This concept evolved in subsequent seasons, with teams increasingly raising the lower rear wishbone to align with the driveshaft. This change allowed for the addition of aerodynamic fairings around the rear leg of the lower wishbone, toe link, and driveshaft.

- Raising Upper Wishbones: To counteract the stiffness loss from raising the lower wishbones, the upper wishbones were also elevated. This necessitated redesigning the upright, extending its depth upward beyond the inside diameter of the wheel to accommodate the new attachment points.

Regulatory Changes

However, regulatory changes introduced for the 2022 season specified that outboard suspension member attachment points must lie within the diameter of the wheel drum (the shroud or "cake tin" surrounding the upright and brake assembly). This effectively outlawed the previous practice of extending upright wishbone attachment points, ensuring that teams adhere to stricter design constraints while balancing aerodynamics and suspension performance.

Suspension Components in F1 Cars

Shrouding for Aerodynamic Efficiency

To minimize the disruption caused by suspension components, shrouds are commonly used around the rear suspension setup. These shrouds help to streamline airflow at the rear of the car by encasing the driveshaft and isolating it from the aerodynamic environment. 

- Regulatory Constraints: Regulations dictate that shrouds must be aerodynamically neutral and positioned horizontally. This necessitates careful design to align with the driveshaft, often requiring compromises in the mechanical performance of the rear suspension.

Innovative Rear Suspension Layout

In 2020, Mercedes innovated the layout of the rear suspension by swapping the positions of the lower wishbone and toe link. Typically, the lower wishbone is located in front of the driveshaft, with the toe link behind it. 

- Benefits of the New Layout: By moving the lower wishbone behind the driveshaft and the toe link in front, Mercedes created a more compact design. This shift allowed for improved airflow to the rear wing and diffuser, enhancing aerodynamic performance. Red Bull Racing followed this design approach with their RB16B in 2021.

Uprights and Axles

The uprights play a critical role in the suspension system, carrying various components essential for the vehicle's dynamics:

- Functionality: They hold the stub-axle bearings, stub axles, brake discs, and calipers, as well as adjustment mechanisms for camber and toe settings. They connect to the wishbones and push/pull-rods.

- Strength Requirements: Given the extreme forces acting on them during acceleration, braking, and cornering, uprights must be incredibly strong. Rear uprights endure torque from the engine transmitted through the axles, while front uprights also bear the loads from steering.

- Cooling Considerations: High brake temperatures necessitate that uprights facilitate effective brake cooling, further complicating their design.

- Stiffness Importance: Any flex in the uprights can adversely affect suspension geometry, tire performance, handling, and overall aerodynamic setup. For drivers, flexing in front uprights can diminish the accuracy of steering feedback.

- Material Use: Until 2009, many teams utilized Metal Matrix Composite (MMC) for uprights, a material blend of aluminum alloy and other composites, to reduce weight.

Suspension Components in F1 Cars

Uprights and Wheel Locking Mechanisms

From the 2010 season, the use of Metal Matrix Composites (MMC) for uprights was outlawed in F1 regulations, leading teams to use stiff aluminum alloys for their construction. 

- Stub Axles: Typically made from steel, stub axles incorporate locking mechanisms to secure the wheel nuts. The end is threaded to accommodate a single wheel nut, which is secured using a two-stage locking mechanism as per regulations.

- Captive Wheel Nuts: Recent developments have focused on making wheel nuts captive within the wheels. This innovation aids alignment and minimizes the risk of cross-threading during rapid pit stops, enhancing efficiency in tire changes.

Wishbones

Most modern F1 cars utilize double wishbones at each corner, with some teams exploring multi-link systems in recent seasons. 

- Material and Design: Wishbones are predominantly made from carbon fiber with metal inserts for mounting to the chassis, gearbox, or rear crash structure. This compact design helps with aerodynamic performance, but it also makes them relatively heavy.

- Configuration: The double wishbone setup features unequal lengths: the lower wishbones are longer than the upper ones. This design helps manage wheel camber angles. During cornering, the longer lower wishbone pushes the bottom of the tire outward more than the shorter upper wishbone pushes the top, which increases the camber angle. This results in a more consistent tire contact patch, thereby improving lateral grip.

- Wheel Diameter Constraints: Because the upright and hub must fit within the wheel's diameter, the attachment points of the wishbones are typically determined by this constraint. 

- Extended Upright Design: Introduced in the 2017 season by teams like Mercedes and Toro Rosso, this configuration features an upright that extends above the wheel diameter via an angled bracket. This allows the top wishbone to be mounted higher and closer to horizontal, offering additional aerodynamic benefits.

Suspension Components in F1 Cars 

Wishbone Design and Regulations

- Non-Parallel Wishbones: The use of non-parallel wishbones allows for greater design flexibility. This configuration helps optimize geometry changes as suspension loads vary, particularly regarding the positioning of the roll center, which is crucial for handling dynamics.

- Aerodynamic Considerations: The placement of upper and lower wishbones is vital not just for suspension performance but also for aerodynamics. To reduce airflow disruption, aerodynamic shrouds are commonly fitted around the wishbones.

- Wheel Tethers: Both front and rear wheels are required to have wheel tethers. These tethers, along with wiring for suspension and brake sensors, are often routed within the wishbones to maintain tidiness and reduce aerodynamic drag.

Structural Integrity and Adjustability

- Testing and Inspection: Given the critical structural role of wishbones, they undergo rigorous testing and regular inspections to ensure they can handle the extreme loads experienced during races.

- Adjustments: While there are no direct adjustments for the wishbones themselves, changes to camber angles are typically made at the uprights. Adjustments for toe angles are made using track rods in the front suspension and toe links in the rear suspension.

Suspension Components in F1 Cars

Uprights and Wheel Locking Mechanisms

- Material Changes: Starting from the 2010 season, the use of Metal Matrix Composites (MMC) for uprights was banned, leading teams to adopt stiff aluminum alloys for durability and performance.

- Stub Axles: Made from steel, stub axles feature locking mechanisms to secure wheel nuts. Each axle is threaded to accommodate a single wheel nut, which must be secured using a two-stage locking mechanism, as mandated by regulations.

- Captive Wheel Nuts: Recent advancements have introduced captive wheel nuts, which are integrated within the wheels. This design enhances alignment and reduces the risk of cross-threading during rapid pit stops, contributing to quicker tire changes.

Wishbones

- Double Wishbone Configuration: Most modern F1 cars use a double wishbone setup at each corner, though some teams have experimented with multi-link systems in recent seasons.

- Material and Structure: Wishbones are primarily constructed from carbon fiber, with metal inserts for secure mounting to the chassis or gearbox. This compact design aids aerodynamic performance, though it does result in added weight.

- Length Variations: The configuration features unequal lengths, with lower wishbones being longer than upper ones. This design helps control wheel camber angles; during cornering, the longer lower wishbone pushes the tire's bottom outward more than the shorter upper wishbone pushes the top, thereby increasing camber angle and maintaining a consistent tire contact patch for improved lateral grip.

- Design Constraints: The placement of wishbone attachment points is often determined by the need for components to fit within the wheel diameter. 

- Extended Upright Design: Introduced in the 2017 season by teams such as Mercedes and Toro Rosso, this configuration utilizes an upright that extends above the wheel diameter with an angled bracket. This allows for a higher and more horizontal mounting of the top wishbone, offering aerodynamic advantages.

Rear Toe Link and Suspension Rods in F1 Cars

Rear Toe Link

- Function: The rear toe link, sometimes called a track rod, connects the upright to the gearbox or rear crash structure, located behind the driveshaft. It includes an adjuster link for modifying the rear toe angle, allowing for fine-tuning of the car's alignment.

- Design Innovation: In 2020, Mercedes altered traditional design by switching the positions of the lower rear wishbone and the toe link, a configuration adopted by Red Bull in 2021. This innovative approach contributes to better aerodynamics and performance.

- Aerodynamic Shrouding: The toe link is typically positioned within an aerodynamic shroud, which conceals it from view and minimizes disruption to airflow around the car.

Push-Rods and Pull-Rods

- Purpose: Push-rods and pull-rods activate the suspension's springs and dampers to counteract vertical wheel movement. They allow these components to be positioned inboard on the chassis or gearbox, enhancing aerodynamic efficiency.

- Mechanics of Operation:

  - Push-Rods: Operate in compression, pushing the rocker when the wheel moves upward over bumps or curbs.

  - Pull-Rods: Operate in tension, pulling the rocker as the wheel moves up.

- Configuration Benefits:

  - A pull-rod system generally allows for a lower mounting of the rocker and spring assembly, benefiting the car's center of gravity and aerodynamics. However, this can complicate access for adjustments.

  - The choice between push-rod and pull-rod systems is often driven by packaging constraints and aerodynamic goals rather than mechanical superiority.

Material and Aerodynamics

- Materials Used: Both types of rods are designed to minimize aerodynamic drag. They can be constructed from carbon fiber with metal inserts for mounting or from metal, depending on the specific design requirements of the car's suspension.

- Ride Height Adjustment: Ride height can be easily modified by altering the length of the push-rods or pull-rods, utilizing shims or threaded adjuster links. Adjusting the effective length allows teams to raise or lower the car's ride height, which is crucial for optimizing aerodynamic performance.

- Adjustment Techniques: 

  - Mechanics can change the adjustment shim on push-rods to alter ride height by loosening a nut, sliding out the current shim, and replacing it with one of a different thickness.

Rear Toe Link and Suspension Rods in F1 Cars

Rear Toe Link

- Function: The rear toe link, also known as a track rod, connects the upright to the gearbox or crash structure, positioned behind the driveshaft. It includes an adjuster link for modifying the rear toe angle, allowing for precise alignment adjustments.

- Design Innovation: In 2020, Mercedes innovatively switched the positions of the lower rear wishbone and the toe link, a design adopted by Red Bull in 2021. This adjustment helps improve aerodynamic efficiency.

- Aerodynamic Shrouding: Typically, the toe link is housed within an aerodynamic shroud, minimizing its visual impact and reducing airflow disruption.

Push-Rods and Pull-Rods

- Purpose: Both push-rods and pull-rods activate the suspension's springs and dampers, which counteract vertical wheel movement. They allow for inboard placement of these components on the chassis or gearbox, which is beneficial for aerodynamics.

- Mechanics of Operation:

  - Push-Rods: Function in compression, pushing the rocker when the wheel rises over bumps or curbs.

  - Pull-Rods: Operate in tension, pulling the rocker as the wheel moves upward.

- Configuration Benefits: A pull-rod system typically allows the rocker and spring assembly to be mounted lower on the car, which lowers the center of gravity and improves aerodynamics. However, this can make access for adjustments more challenging. The choice between push-rod and pull-rod systems is influenced more by packaging and aerodynamic needs than by mechanical advantages.

Material and Aerodynamics

- Materials Used: Push-rods and pull-rods are designed to minimize aerodynamic drag and may be constructed from carbon fiber with metal inserts for mounting, or entirely from metal, depending on the specific design requirements.

- Ride Height Adjustment: The car's ride height can be easily modified by adjusting the lengths of the push-rods or pull-rods using shims or threaded adjuster links. 

- Adjustment Techniques: For example, a mechanic can change the adjustment shim on a push-rod by loosening a nut, sliding out the existing shim, and replacing it with a different thickness to alter the ride height. This adjustment can be made either at the inboard mounting or at the upright mounting point.

Torsion Bars, Dampers, and Heave Spring/Damper Units in F1 Cars

Torsion Bars

- Function: Torsion bars are longitudinal springs running along the car, mounted at the front chassis or gearbox casing. They act as pivots for the suspension rockers and provide resistance when the wheel moves upward over bumps.

- Operation: As the wheel and upright move up, they push or pull the push-rod or pull-rod, which then moves the rocker. The rocker pivots and twists the torsion bar, providing an opposing force. By changing the torsion bars, teams can adjust the effective spring rate to suit different track conditions.

Dampers

- Purpose: Dampers control oscillations of the suspension springs to keep the tires in maximum contact with the track. They are tunable, with adjustable valving for both bump (compression) and rebound (extension).

- Weight Considerations: Since refueling was banned starting in **2010**, a car's weight during a race becomes variable as fuel is consumed. This variability complicates the set-up process and often necessitates compromises in damping settings.

- Motion Ratio: The damping action depends on the speed at which the piston moves through the fluid, determined by the "motion ratio." A 1:1 motion ratio means the piston moves exactly as the wheel does, while a 0.5:1 ratio means the piston moves half as far. Changes in the car's mechanical setup can affect the motion ratio, requiring corresponding adjustments in damper valving.

- Design: Most teams utilize bespoke, fluid-filled, linear dampers. These are typically configured as four-way dampers, allowing independent adjustments for high- and low-speed damping. 

- Current Systems: Recent configurations often use two dampers at each end of the car: a heave damper connecting the two rockers and a single roll damper connected diagonally. This setup provides effective control over both roll and heave dynamics.

Heave Spring/Damper Units

- Definition: Heave spring/damper units, sometimes called "third springs" or "third elements," are connected between the suspension rockers at both the front and rear of the car. They compress when both wheels on an axle move vertically together (pitching).

- Functionality: The heave unit dampens pitch without affecting roll stiffness. This is particularly important in modern F1 cars where aerodynamic performance has become paramount.

- Importance: With aerodynamics playing a dominant role in performance, heave spring/damper units help teams fine-tune their setup for better handling and stability, particularly during high-speed cornering and braking.

Dampers and Heave Spring/Damper Units in F1 Cars (Continued)

Damping Action and Motion Ratio

- Damping Action: A damper's effectiveness is influenced by the speed at which its piston moves through the fluid. This speed is determined by the "motion ratio" of the rocker operating the piston.

- Motion Ratio Explained:

  - A 1:1 motion ratio indicates that the piston moves the same distance as the wheel.

  - A 0.5:1 motion ratio means the piston moves only half as far as the wheel.

- Impact of Mechanical Setup: The motion ratio is affected by the arc of the rocker’s movement, which changes with the car's mechanical setup, primarily ride height. Significant changes to the setup will require adjustments to damper valving to maintain optimal performance. However, teams usually establish a base setup that requires minimal alterations to the damper settings.

Damper Design

- Types of Dampers: Most F1 teams use bespoke fluid-filled, linear dampers tailored to their car's specific packaging and suspension characteristics.

- Adjustability: These dampers typically feature four-way adjustability with independent high- and low-speed damping. Removable valving cartridges allow for easy adjustment of bump and rebound settings.

- Recent Trends: Traditionally, F1 cars had three dampers at each end: one roll damper per side and one heave damper connecting the rockers. Recently, a two-damper system has become more common, consisting of:

  - A heave damper connecting the two rockers horizontally.

  - A single roll damper connected diagonally between the rockers. This configuration provides sufficient adjustability to control both roll and heave effectively.

- Remote Reservoirs: Many F1 dampers feature remote reservoirs, which help with component packaging and efficiency.

Heave Spring/Damper Units

- Definition: Heave spring/damper units (or "third springs") are connected between suspension rockers at both the front and rear of the car. They are designed to compress when both wheels on an axle move vertically together.

- Functionality: The heave unit dampens pitch without affecting roll stiffness, which is crucial for maintaining aerodynamic performance during cornering.

- Importance: As aerodynamics has become a critical factor in F1 performance, the ability to manage heave independently from roll has gained significance. This allows teams to optimize handling and stability, especially during dynamic race conditions.

Anti-Roll Bars and Inerters in F1 Suspension Systems

Anti-Roll Bars

- Function: Front and rear anti-roll bars are designed to resist the car's tendency to roll during cornering. They are crucial for adjusting the mechanical balance of the car.

- Connection: Anti-roll bars connect the left and right sides of the car, typically fitted between the push/pull-rod rockers.

- Torsion-Bar Anti-Roll Bars: Many teams have adopted torsion-bar designs, which resist twisting as the rockers on each side rotate out of phase. This allows for easy adjustments of the anti-roll bar's characteristics.

- Twin-Rocker Systems: Some teams have experimented with a twin-rocker anti-roll bar system, where an additional rocker connects to the torsion-bar springs. This setup allows the inner ends of the blades to slide within a guide link, effectively resisting roll while remaining neutral during heave.

- Adjustability: Anti-roll bars can be modified during practice sessions to fine-tune the car's setup for optimal performance.

Inerters

- Introduction and Development: The concept of the inerter was developed by Professor Malcolm C. Smith during his work on active suspension systems in the late 1980s and early 1990s. After patenting the design in 2001, McLaren introduced it in the 2005 season.

- Functionality: An inerter functions like a mechanical capacitor, storing energy during tire movement. It helps reduce tire oscillations, improving grip and stabilizing the aerodynamic platform.

- Operation Principle: The inerter has two movable connections, where linear forces applied to these connections are equal and opposite. The force is proportional to the relative acceleration between the two connections.

- Impact on Suspension: Inerters work alongside springs and dampers, enhancing the overall efficiency of the suspension system. They became an integral part of F1 car suspension until the end of 2021.

- Design Considerations: Various designs exist for inerters, and their implementation must consider the specific packaging and performance requirements of an F1 car.

Inerters in F1 Suspension Systems

Design Variations

- Secrecy and Complexity: Teams have kept specific details of their inerter designs secret, and various configurations have been used across the grid.

- Suggested Designs by Professor Smith:

  - Hydraulic Device: Operates through hydraulic mechanisms.

  - Rack-and-Pinion Design with Flywheels: Movement of the rack spins dual flywheels, generating opposing force.

  - Threaded Rod Design: A threaded rod connected to one mounting, with a flywheel inside the casing that spins to oppose movement as the rod shifts.

- Common Choices: Most teams have opted for the concentric flywheel design, while some employed complex hydraulic systems.

- Installation: Inerters were fitted at the front and rear of the car, replacing traditional heave dampers.

- Optimization: Effective integration of the inerter with other suspension components is crucial for optimal performance.

Regulatory Changes

- 2022 Regulations: The introduction of new regulations banned the use of inerters. Additionally, the transition to larger and heavier wheels and tires from 2022 reduced the efficacy of the inerter concept.

FRICS (Front and Rear Inter-Connected Suspension)

- Historical Context: The FRICS concept emerged in the 1990s but gained widespread use as teams sought to optimize aerodynamic performance. By 2014, it had become common, though teams agreed to disconnect the systems mid-season following FIA investigations.

- Interconnection Scope: While the name suggests a focus on front and rear suspension, some teams interconnected all four corners, allowing precise control over pitch, roll, and heave.

- Functionality: FRICS aimed to maintain a stable aerodynamic platform by managing ride height changes due to varying loads during cornering, braking, and acceleration. This system helped keep the car's floor attitude consistent relative to the track surface.

- Technical Implementation: Most teams utilized hydraulic systems for interconnecting suspension components, including springs and dampers at all four corners, with some integrating inerters into the system for enhanced control.

- Complexity and Cost: The intricacy and cost of developing FRICS systems contributed to their discontinuation.

Active vs. Reactive Suspension Systems in F1

Active Suspension

- Historical Context: Active suspension systems first emerged in the 1980s, with teams like Williams pioneering the technology. The FW14B and FW15C are notable examples that dominated the 1992 and 1993 seasons.

- Functionality: These systems aimed to maintain a consistent ride height, providing a stable aerodynamic platform. They utilized hydraulic actuators to replace conventional spring/damper/anti-roll-bar arrangements.

- Control Mechanism: Active systems employed electronic control systems and sensors to monitor the car’s dynamics. By separating load-bearing capability from suspension movement, they achieved precise control over ride height, both in straight lines and during cornering, which significantly improved aerodynamic consistency and lap times.

FRICS (Front and Rear Inter-Connected Suspension)

- Nature of Operation: Unlike active systems, FRICS is a reactive system. It responds to inputs transmitted through the suspension components directly from the track surface, without active control mechanisms.

- Functionality: While FRICS helps manage ride height changes and improves handling by interconnecting suspension components, it does not independently adjust the vertical movement of the wheels based on external conditions.

Key Differences

- Control: Active systems use hydraulic actuators and sensors for dynamic control, while FRICS systems respond passively to track conditions.

- Performance Enhancement: Active suspension offers a higher level of precision in maintaining optimal ride height, leading to enhanced aerodynamic performance compared to reactive systems like FRICS.