Chassis

The tub must be able to withstand the huge forces produced by the high cornering speeds, bumps and aerodynamic loads imposed on the car. The tub is first designed on a Computer Aided Design (CAD) package and from these designs, a computer controlled machine cuts pieces of ureol to make a mock up from which a mould is made.. This material is not unlike wood, but is man-made and does not absorb water. It is also grain less and does not expand under temperature and so a very accurate model of the chassis can be made. This chassis model is then covered in carbon fibre to create a mould from which the actual chassis can be made. Once produced the mould is smoothed down and covered in release agent so the carbon-fibre tub can be easily removed after manufacture.

The mould is then carefully filled inside with layers of carbon fibre. This material is supplied like a typical cloth but can be heated and hardened. The way the fibre is layered is important as the fibres can direct stresses and forces to other parts of the chassis, so the orientation of the fibres is crucial. The fibre is worked to fit exactly into the chassis mould, and a hair drier is often used to heat up the material, making it stick, and to help bend it to the contours of the mould. After each layer is fitted, the mould is put into a vacuum machine to literally suck the layers to the mould to make sure the fibre exactly fits the mould. The number of layers in the tub differs from area to area, but more stressed parts of the car have more , but the average number is about 12 layers. About half way between these layers there is a layer of aluminium honeycomb that further adds to the strength.

Once the correct number of layers have been applied to the mould, it is put into a machine called an autoclave where it is heated and pressurized. The high temperatures release the resin within the fibre and the high pressure (up to 100 psi) spueezes the layer together. Throughout this process, the fibres harden and become solid and the chassis is normally ready in two and a half hours. The internals such as pedals, dashboard and seat back are glued in place with epoxy resin and the chassis painted to the sponsors requirements.

The fuel tank, or 'cell', is located immediately behind the drivers seat, inside the chassis. The cell is made from two layers of rubber, nitrate butadiene, with the outer layer being kevlar reinforced to prevent tearing. The cell is like a bag, it can deform without tearing or leaking. The cell is made to measure exactly and is anchored to the chassis to prevent it moving under the high g-forces. The inside of this tank is very complex and contains various section to stop the fuel sloshing around, and there are up to three pumps sucking out the fuel so to get every last drop. These pumps then deliver the fuel at a constant rate to the single engine fuel pump. The link between the fuel tank and the engine is a breakaway connection so that the fuel flow is stopped automatically if the engine is ripped off the chassis in a large accident. Size of fuel tanks vary, but Jordan's fuel cell holds 135 litres. The picture below shows the tub complete with front suspension:

F1 Engines

The formula one engine is the most complex part of the whole car. With an amazing horsepower production and about 1000 moving parts, this sort of engine makes the greatest cost on a F1 car. Incredible revs exceeding 17,000 rpm and extreme high temperatures make it very hard to make that engine reliable. This table shows current FIA limitations concerning an engine.

• Engine capacity must not exceed 3000 cc.
• Engines may have no more than 5 valves per cylinder.
• Supercharging is forbidden.
• An engine must consist of 10 cylinders and the normal section of each cylinder must be circular.
• The use of any device, other than the 3 litre, four stroke engine to power the car, is not permitted
• Variable geometric length exhaust systems are forbidden.
• The basic structure of the crankshaft and camshafts must be made from steel or cast iron.
• Pistons, cylinder heads and cylinder blocks may not be composite structures which use carbon or aramid fibre reinforcing materials.
  

At the moment, all f1 engines can produce more than 780 bhp with 10 cilinders in V. These engines are mainly made from forged aluminium alloy, because of the weight advantages it gives in comparison to steel. Other materials would maybe give some extra advantages, but to limit costs, the FIA has forbidden non-ferro materials. In this quest to decrease engine weight, the 1998 Mercedes-benz engine was possibly one of the most revolutionary engines ever built. Ford started a new trend that year to drastically decrease the weight of the engine, and thus also improving its performance. Ford Cosworth had been able to produce an engine that was at least 25kg lighter than any other engine. Although they suffered some reliability problems trghout the season, the engine was an example for the others, as it allowed teams to shift some weight in the car. That could be placed more on the front wheels or on the rear wheels which could help the steering or the acceleration of the car.

It's not exactly known how much oil such a top engine contains, but this oil is for 70% in the engine, while the other 30% is in a dry-sump lubrication system that changes oil within the engine three to four times a minute.

Difference with road engines

• Higher volumetric efficiency. VE is used to describe the amount of fuel/air in the cylinder in relation to regular atmospheric air. If the cylinder is filled with fuel/air at atmospheric pressure, then the engine is said to have 100% volumetric efficiency. On the other hand, turbo chargers increase the pressure entering the cylinder, giving the engine a volumetric efficiency greater than 100%. However, if the cylinder is pulling in a vacuum, then the engine has less than 100% volumetric efficiency. Normally aspirated engines typically run anywhere between 80% and 100% VE. So now, when you read that a certain manifold and cam combination tested out to have a 95% VE, you will know that the higher the number, the more power the engine can produce. Bacause turbos are not allowed in F1, this item does not differ that much from a normal road engine.
• Unfortunately, from the total fuel energy that is put into the cylinders, everagely less than 1/3 ends up as useable horsepower. Ignition timing, thermal coatings, plug location and chamber design all affect the thermal efficiency (TE). Low compression street engines may have a TE of approximately 0.26. A racing engine may have a TE of approximately 0.34. This seemingly small difference results in a difference of about 30% (0.34 - 0.26 / 0.26) more horsepower than before.
• From all that power generated, part of it is used by the engine to run itself. The left over power is what you would measure on a dynamometer. The difference between what you would measure on the dyno and the workable power in the cylinder is the mechanical efficiency (ME). Mechanical efficiency is affected by rocker friction, bearing friction, piston skirt area, and other moving parts, but it is also dependent on the engine's RPM. The greater the RPM, the more power it takes to turn the engine. This means limiting internal engine friction can generate a large surplus in horsepower, and where in F1 the stress is on power, on the road it is also on fuel consumption.

These main optimization necessities are what causes the engineer's headaches. At the end of the line, an F1 engine revs much higher than road units, hence limiting the lifetime of such a power source. It is especially the mechanical efficiency that causes formula one engines to be made of different materials. These are necessary to decrease internal fraction and the overall weight of the engine, but more importantly, limit the weight of internal parts, e.g. of the valves, which should be as light as possible to allow incredibly fast movement of more than 300 movements up and down a second (this at 18.000 rpm).

Another deciding point trying to reach a maximum of power out of an engine is the exhaust. The minor change of lenght or form of an exhaust can influence the horsepowers drastically (for more information about exhausts, look at the article concerning this topic in the Mechanics part).

Engine type

Considering internal combustion engines (thus leaving out oscillating and Wankel rotary combustion engines), there are basically three different types of building an engine. The difference here is how the cylinders are placed compared to each other.

• Inline engines, where all cylinders are placed next to (or after) each other are not used in Formula one since the 60's.
• Boxer engines are actually one of the best ways to build an engine, if all external factors allow it. Two cylinder rows are placed opposed to each other. These engines became popular in F1 because of the low point of gravity, and the average production costs, but later on disappeared out of the picture as this type of engine is not sufficiently stiff enough to whitstand the car's G-forces in cornering conditions.
• V-type engines, as currently used in all F1 cars. As you can see on the picture, it is the same principe as a boxer engine, although the cylinder rows are located both above the cranck shaft, where in boxer engines, these are constructed aside it. With this type of engine, the first question you should ask yourself is how large should the V angle be. Currently most F1 cars run with a 72°, Renault runs a 112° engine in order to obtain a lower gravity point but having to cope with more vibrations and a decreased stiffness of the engine part.

The size of the V angle has to do with firing sequence and primary balance. A circle has 360 degrees and the (included V angle x the number of cylinders) must be a function of 360 in order to achieve evenly spaced cylinder firing and primary balance. That is why a 90 V has either offset crankpins or a funny firing order. That is why a boxer engine is an ideal layout. The cylinders are opposed at 180 degrees so having 2 or 4 or 6 or 8 or 10 or 12 isn't that big a deal. Perfect primary balance is easy to achieve, as long as the reciprocating and rotating parts are in balance and, the firing order is always evenly spaced. However, a boxer in an F1 car would be ungainly.

Cooling

Just above the driver's head there is a large opening that supplies the engine with air. It is commonly thought that the purpose of this is to 'ram' air into the engine like a supercharger, but the airbox does the opposite. Between the airbox and the engine there is a carbon-fibre duct that gradually widens out as it approaches the engine. As the volume increases, it makes the air flow slow down. The shape of this must be carefullly designed to both fill all cylinders equally and not harm the exterior aerodynaimcs of the engine cover, this all to optimize the volumetric efficiency.

This picture shows the whole engine part and surroundings on the Toyota F1 car of 2002. The black carbon box above the engine is the airbox, providing air to the engine to be mixed with fuel in the cylinders. Secondly, the flat panels located nearly vertically in the front of the side pods are the radiators. These use air flowing through to cool down the engine and its oil. The position can vary a lot, as it is not a much importance as long as it can catch enough air, preventing the engine to overheat. One thing that greatly influences the radiator positioning is to lower the side pod and improve the coke bottle effect, thereby optimizing aerodynamic efficieny.

Transmission

Considering the enormous power the engine produces at full throttle, it's not a piece of cake to transmit it nicrely and with the least possible power loss to the rear wheels. All parts of the tranmission can be named a gearbox, as it is just a name as it looks like one case to the outside with some electronics and the suspension, which has actually nothing to do with the engine, although it is fitted onto the gearbox, as are all the rear car parts. The gearbox is in fact the most differing part in comparison to a road car's gearbox.

The weight for example, the height from the ground and the size are the most logical. But thinking that a transmission can be as hot as 1000°C when the power is brought to the wheels at the start of each race is certainly very important for the engineers. Each team builds their own gearbox, either independently or in partnership with companies such as X-trac. The regulations state that the cars must have at least 4 and no more than 7 forward gears as well as a reverse gear. All teams are currently using gearboxes with 7 forwards gears and one reverse, with the 7 forward gear introduced by Ferrari in 1999.

In contrast to the more usual type, f1 gearboxes are part of the carrying chassis, thus undergoing lots of different forces. It is directly attached to the engine with 6 bolts. To be able to deal with the forces and be strong enough in crashes, it is normally made of fully-stressed magnesium or carbon fibre (new since 1998, introduced by Stewart and Arrows). The gearbox on the other hand is linked directly to the clutch, made from carbon fibre. Two manufacturers, AP racing and Sachs produce F1 clutches which must be able to tolerate temperatures as high as 500 degrees. Clutches are electro-hydraulically operated and can weigh as little as 1.5 kg. Each gearchange is controlled by a computer, taking between 20-40 milliseconds, thereby only needing the driver to manually operate the clutch at a starting procedure.

Gear cogs or ratios are used only for one race, and are replaced regularly during the weekend to prevent failure, as they are subjected to very high degrees of stress. Oil within the gearbox usually operates at 125 degrees, and in theory, metal never touches metal due to the high performace and quality of oil that is used.

Transmission

Just like in your family road car, F1 cars have a clutch, gearbox and differential to transfer the 900 bhp into the rear wheels. Although they provide the same same function as on a road car, the transmission system in an f1 car is radically different....

Clutch

The engine is linked directly to the clutch, fixed between the engine and gearbox. Two manufacturers, AP racing and Sachs produce Carbon/Carbon F1 clutches which must be able to tolerate temperatures as high as 500 degrees. The clutch is elctro-hydraulically operated and can weigh as little as 1,5 kg.

They are multi-plate designs that are designed to give enhanced engine pick-up and the lightweight deigns mean that they have low inertia, allowing faster gear changes. The drivers do not manually use the clutch apart from moving off from standstill, and when changing up the gears, they simply press a lever behind the wheel to move to the next ratio. The on-board computer automatically cuts the engine, depresses the clutch and switches ratios in the blink of an eye. The picture shows the range of clutches produced by AP Racing. The clutches on the left are designed for road based racing or rally cars, whilst those on the right are the ones used in F1 cars, and are only 100 mm in diameter.

Gearbox

F1 car gearboxes are different to road car gearboxes in that they are semi-automatic and have no synchromesh. They are sequential which means they operate much like a motorcycle gearbox, with the gears being changed by a rotating barrel with selector forks around it. The lack of a synchromesh means that the engine electronics must synchronise the speed of the engine with the speed of the gearbox internals before engaging a gear.

Each team builds their own gearbox either independently or in partnership with companies such as X-trac. The regulations state that the cars must have at least 4 and no more than 7 forward gears as well as a reverse gear. Most cars have 6 forward gears, although there is the start of a trend towards using seven. Seven speeds are used if an engine has a narrow power band, having more ratios in the gearbox keeps the engine working in this ideal band. The gearbox is attached to the back of the engine via four or six high-strength studs, with both the engine and gearbox being fully stressed members of the car. The suspension for the rear wheels bolts directly onto the gearbox casing, carrying the full weight of the rear of the car. As a result, the gearbox must be very strong, and so it is normally made from fully-stressed magnesium. In 1998, Stewart and Arrows produced gearbox casings made from carbon-fibre. This helped weight distribution but caused many problems related to heat and the forces imposed by the suspension arms. Minardi were the first team to fabricate their gearbox out of titanium in 2000, having advantages of a 5 kg decrease in mass when compared with forged magnesium. Ferrari have followed suit, using fabricated titanium parts in the gearbox of the 2001 car. The 2000 Minardi gearbox produced by CRP Technology is shown above left.

Gear cogs or ratios are used only for one race, and are replaced regularly during the weekend to prevent failure, as they are subjected to very high degrees of stress. The gear ratios are an important part of the set-up process of the car for each individual track. The teams will adjust the final gear (sixth or seventh depending on how many gears their gearbox have) so that the car will just be approaching the rev limit at the end of the straight. (For the race it will be a few revs less than the limit to allow for the revs to rise in the slipstream of another car.) Next, the lowest gear needed on the track will be adjusted to give the best acceleration out of that corner, then the other gears will be chosen so that they are spaced out equally between the two pre-determined gears.

F1 cars have a reverse gear, but these are designed to satisfy the regulations rather than being of much practical use. Most teams build avery small and flimsy reverse gear on the outside of the gearbox to help keep the weight of the gearbox down, as reverse gear is seldom used (apart from the odd trip down an escape road at Monaco...)

Each gearchange is controlled by a computer, taking between 20-40 milliseconds. The gearbox is built to enable the mechanics to easily change the ratios, as they can even be dependent on the wind direction. It takes about 40 minutes for the six ratios to be changed in the pits.

Differential

To enable the rear wheels to rotate at different speeds around a corner, F1 cars use differentials much like any other forms of motorised vehicle. Formula One cars use limited-slip differentials to help maximise the traction out of corners, compared to open differentials used in most family cars. The open differential theoretically delivers equal torque to both drive wheels at all times, whereas a limited slip device uses friction to change the torque relationship between the drive wheels. Electro-hydraulic devices are used in F1 to constantly change the torque acting on both of the drive wheels at different stages in a corner. This torque relationship can be varied to 'steer' the car through corners, or prevent the inside rear wheel from spinning under harsh acceleration out of a bend.

The FIA allows the use of these devices provided that their characteristics are fixed once the car is out on the track. A Moog valve will constantly adjust the friction between the two shafts around the track to maximise the performance of the car dependent on what characteristics have been entered into the on-board computer. The Moog valve opens and closes depending on what the software is telling it to do, but the valve must work to the same set of conditions that are pre-programmed whilst the car is in the pits. This means that the driver cannot actually alter the characteristics of the differential due to a change in tracks conditions for instance, which was allowed in the days of the many driver aids around 1993.

Brakes

In physical terms we can state that energy is the power to do work. When a car comes down a straight line at 300 km/h or more, that car has lots of kinetic (movement) energy. Due to the fact that energy does not get lost, but can only be transformed one kind into another, at braking most of the kinetic energy is transformed into potential energy, more specifically warmth. Formula One cars must sometimes decelerate in a matter of seconds from 350 km/h to about 70 km/h. This procedure generates enormous heat, resulting in brake temperatures up to 1000°C, where on the end of the straight, right before braking, that is nearly 400. That 1000°C occurs at the end of the braking, and is about the highest temperature a carbon brake disc (as they are used in F1, and limited to 28mm thickness and 278mm diameter by the FIA) can take.

Facts and figures

A mere 4 seconds is the amount of time it takes for a Formula One car to go from 300km/h to a complete halt. At 200 km/h, a Formula One contender requires just 2.9 seconds to stop completely, a process that will have been accomplished over 65 meters. At 100km/h, these values are just as mind-blowing: 1.4 seconds and 17 meters! Under these heavy braking periods, a driver is subjected to a horizontal deceleration of close to 5,2G.

The only configuration that allows this performance at the moment is a brake disc/caliper combination of carbon fibre. Its crude performances fast decelerations while its weight allows for each break-disk to remain below the1 kg/each mark. Furthermore, its capacity to take on and dissipate heat provides unequalled longevity: even when heated to over 1000°C prior to cornering, about 800 times per race, the carbon-fiber will last for the duration of a Grand Prix event without complaint. Steel, used until the 80's, was abandoned without any regrets and the overall performance in F1 came out on top.

”The use of carbon-fibre brakes requires a little time to get used to,” states Jarno Trulli. “In fact, during the first milliseconds after pressing the brake-pedal; it feels like nothing is happening.” This delay is in fact the length of time required by the disk/caliper tandem to reach operating temperature, which increases by 100°C per tenth of a second for the first half-second of braking, after which it can reach up to 1200°C. After that short period, deceleration is immediate, and brutal.

From within their cockpits, drivers can adjust the distribution of braking power between the front and rear of their contenders.This influences the handling of the car. Generally speaking, the front has a priority to within a 51% to 60% margin, depending on track conditions. During a race, reducing the rear braking power allows for reduced rear tyre-wear and thus influences the traction.

General construction

The most important elements of a brake system is the brake disc, rotating at the same speed of the wheel. Today, these are made from carbon, while CART still uses steel brake discs. This material is responsible for the brake power advantage Formula one has to CART. The brakepad with brake blocks are located aside and around the brake disc. When the driver pushes the brakepedal, the blocks are pressed against the brake disc, which slows and heats up according to the friction that occurs (dependent on the brakepower the driver asks by pushing the pedal down).

The rotating discs are gripped by a calliper which squeezes the disc when the brake pedal is pushed. Brake fluid is pushed into pistons within the calliper to push the brake pads onto the disc to slow the wheel down. The discs are often drilled (as shown in the drawing below) so that air will flow through and keep the temperature down.

The picture on the right shows the two brake master cylinders on the Ferrari F1-2000, only visible when the nose cone is removed. These master cylinders contain the brake fluid for both the front and rear brakes. The front and rear systems are connected separately so if one circuit would fail, the driver would still have either the front or rear system with which to slow the car. Also visible is the steering rack and the plumbing for the power steering system.

A newer thing in formula one are the brake ducts. Ferrari introduced these in 2001, with all other teams having it adopted by the end of the season. The right picture shows the box on the inside of the wheel, and the smaller air inlet. The brake duct actually contains a large fan, that rotates around the wheel's axis (upright) and at its same speed. It is in a way some kind of a gas turbo for the cooling of the brakes, powered by the rotating wheel. This causes the fan to rotate very quickly at high speeds, and thus sucking air onto the brakes, where without a brake duct, the air is pushed onto it, just guiding the air to the brake. This brake duct allows the air inlet to be way smaller than it used to be, which generated a considerable aerodynamic advantage.

McLaren	Ferrari

Elements

These brakes are extremely expensive as they are made from hi-tech carbon materials (long chain carbon, as in carbon fibre) and they can take up to 5 months to produce a single brake disk. The first stage in making a disc is to heat white polyacrylo nitrile (PAN) fibres until they turn black. This makes them pre-oxidised, and are arranged in layers similar to felt. They are then cut into shape and carbonised to obtain very pure carbon fibres. Next, they undergo two densification heat cycles at around 1000 degrees Celsius. These stages last hundreds of hours, during which a hydrocarbon-rich gas in injected into the oven or furnace. This helps the layers of felt-like material to fuse together and form a solid material. The finished disc is then machined to size ready for installing onto the car.

The main company that makes brakes for F1 cars is Brembo. Carbon discs and pads are more abrasive than steel and dissipate heat better making them advantageous. Steel brakes as used in CART are heavier and have disadvantages in distortion and heat transfer. Metal brake discs weigh about 3 Kg, carbon systems typically 1.4 Kg. Metal brakes are advantageous in some aspects such as 'feel'. The driver can get more feedback from metal brakes than carbon brakes, with the carbon systems often being described like an on-off switch. The coefficient of friction between the pads and the discs can be as much as 0.6 when the brakes are up to temperature. You can often see the brake discs glowing during a race, this is due to the high temperatures in the disc, with the normal operating temperature between 400-800 degrees Celsius.

Suspension

Unless formula one car suspensions have an incredible stifness, these are one of the most important things to make a car drivable. It is probably one of the most difficult things that can be set on a car, and influences understeer and oversteer hugely. As tires are the only contact between the car and the road surface, you can image how important it is to keep the tires as good as possible on the track, no matter what bump or speed the car may encounter.

Forces to cope with

Weight transfer is the general term for most forces a car undergoes in any change of condition. It is a shifting of loading on the four outmost corners of the car. Acceleration means load is transferred to the back of the car, the opposite occurs when braking. In corners, most weight becomes lying in the two outside wheels. These kinds of weight transfer can be expressed and calculated with the following formula:

• with dW symbolising the total weight transfer due to an acceleration a (m/s²),
• a total vehicle mass m  (in kg),
• h the height is the height of center of gravity,
• t is the track width. (For longitudinal weight transfer, use wheel base instead of t).

Different types of weight transfer:

• Heave is the motion of the chassis when all four wheels go up or down in unison i.e. when a car drives through Aux Rouges at Spa, that car is pushed down onto the track, due to the surface which is basically a narrow valley. When thus driving over a hill, the opposite occurs and the car wants to fly away.
• Pitch is when the front and rear of the chassis go in opposite directions, either up or down. This occurs at braking when the car seemingly bends forward, or accelerating so that the car want to raise its nose.
• Roll is a side-to-side movement of the car. The suspension on the outer side of the car compresses while the inner suspension extends. This occurs during cornering.
• Warp is the movement of the diagonally opposed wheels in opposite directions i.e. the front left suspension compresses as the right rear extends.
• Yaw is the rotation of the car in a horizontal plane around a vertical axis. This occurs during cornering.

Weight transfer has to be absorbed or taken up by the suspension system, otherwise it will be expended at the tire contact patch meaning a loss of adhesion and a spin-out. How this weight is divided between the front end suspension and the rear end suspension is a relationship known as "roll couple distribution".

Suspension technology

The above picture shows the virtual front of a formula one car without its nose. I must say virtually, as in reality, the rockers (see further) cannot be seen when taking off the nose, as they are placed a little deeper into the chassis.

Pushrod and pullrods are the diagonal bars between the car's body and the upright (where the suspernsion arms are attached to the wheels, near the brakes). There is always one for each wheel, but a car does not have pull and push rods at the same time. That would be completely useless, as these arms just do the same, it's only another way to get the same effect. The difference can be found in its name, as the pull rod pulls the rocker, while the push rod pushed it. On the picture we have push rods (when the wheel is pushed up, due to a burb or something, the push rod pushed the rocker up) connecting a rocker in the upper part of the chssis with the lower upright. A pull rod goes the other way, connecting a rocker located low in the chassis, with the upper site of the wheel, almost where the upper suspension arms meet the upright.
Pull rods were first brought to Formula 1 by Gordon Murray with Brabham in the 70s but now all formula one teams make use of the push rods, as pull rods are quite hard to implement in a high nosed car. The advantages of a pull rod lie in the possibility to make the nose lower, assemble most suspension parts lower to the ground and thus lowering the height of the center of gravity.

Rockers are also known as bell cranks or linkages. This is the lever that translates the push\pull rods motion into the rotary force on the torsion bar and the up\down motion of the damper. the rocker also has mounts for antiroll bars and sensors for wheel travel. The rocker translates the wheel movement onto the dampers with a multiplicator. The movements of the damper are thus larger than those of the wheel itself. That means if a wheel moves 1cm, the damper will undergo a movement of about 2 to 3 cm (these are only estimated numbers). It's partially this principly of multiplicating the movement onto the damper that causes the enormous stiffness of the suspension.

On this particular drawing you can also notice the torsion bar passing trough the middle of the rockers. The torsion bar is thereby fixed onto the chassis, allowing the rocker to rotate around it. When a wheel pushed the rocker up, it twists and pushed the damper down.

As you can also see on the picture, both rockers on each side are connected with each other with an anti-roll bar (roll : see types of weight transfer). Anti-roll bars resist roll by twisting themselves, acting as torsion springs. The anti-roll bar should be handling approximately 50% of the front roll resistance, with the other 50% split between the front springs. To avoid some misunderstandings, a roll bar has nothing whatsoever to do with spring rate. Changing bars can only make the front end stiffer or softer in terms of roll rate and not spring rate.

What cannot be seen on this image are the springs, which absorb bumps, limit the motion of the vehicle due to acceleration, braking, cornering, etc.

Shock absorbers on the other hand dampen the motion of suspension. They do not absorb impacts, but damp the motion of the vehicle. As the name itself says, it particularly acts on the first impact, while the springs work during all  the event. If you would have a car with springs, but no or bad shock absorbers, you will keep bumping up and down for a while, and in corners, a wheel might get off the ground a lot easier, because the opposite wheel bends down too much. Shock absorbers are thus tie-down devices for springs which control the springs' oscillation. Oscillation is the up and down movement of a spring, and unless it has a damping device on it, the spring will oscillate infinitely until internal friction in the spring stops its movement. Shock absorbers can be adjusted for "rebound' and "bump".

Packers or bump rubbers can be used to prevent the springs or torsion bars compressing too far. This allows the suspension to be soft, and preserverves the car to hit the ground due to the high downforce. These packers should although not come into play in corners, because if the suspension is that soft that it leans on the packers in a corner, no more energy is dissipated into the suspension, which results in decreased grip. They are useful on modern cars to preserve the wooden plank under the car, the rules stating that no more than 1 mm can be worn during the race. (Hence Schumacher's exclusion from Spa 1994)

Tyres

Tyres regulations have changed a lot in Formula One history in order to limit cornering and acceleration speeds of the cars. After all, the tyres are the only contect patch between a car and the ground. It needs no explanation that any change in tyre regulation can greatly influence the performance of a racecar. It is therefore very important for the FIA to study all possibilities if they decide to change any of these regulations. Changes of tyre width had proven to have the opposite effect than intented. A smaller tyre in fact reduces grip, but it also reduces aerodynamic drag, hence enabling higher straight speeds. It was also a considerable advantage that the corners could be taken sharper, as the total width of the car was reduced a little.

Tyre basics

The more rubber, the more grip. To get the maximum amount of grip out of a tyres, the tyre is as wide as possible, which means exactly the maximum limit the FIA has set. Another advantage from having as much as possible tyres thread is to decrease wear, as more rubber surface absorbs wear better, this extending the lifetime of a tyre, or allowing the manufactures to use softer rubber compounds.

To compensate for lost footprint area in F1 tyres, compared to the optimal (maximal diameter) size, tyre engineers are designing the smaller diameter tyres with more flexible sidewalls so more tyre will come in contact with the track. Judging from this knowledge, it is wise to choose a tyre with a taller carcass when running on a track with a rough or bumpy surface so the stiffer sidewall will help cope with the bumps and irregularities.

Manufacturing and design

Comprising more than one hundred ingredients, the compound is based on three main elements: carbon, oil and sulphur. More or less soft depending on the characteristics of each circuit, this sector changes considerably from one race to the next, whereas the structure evolves little by little throughout the season. The structure is composed of a Nylon and polyester framework, in a complex weave. This is the skeleton of the tyre. It provides rigidity against high aerodynamic load (more than one tonne of force at 250 km/h), strong longitudinal forces (4 G), lateral forces (5 G), and violent crossing of the vibrating strips. The problem to be solved on the dry, as regards structure, comes from the specificity of the grooves: changes in direction become harder, as the rubber in contact with the track between the grooves has a tendency to become deformed. Another headache.

The performance of the grooved tyre is a result of the interactions between dimensions-compound-structure-track-car... which changes significantly 17 times during a season. This balance to be found is called "centring" by the Michelin engineers. For each race, the margin of manoeuvre is small: only two types of tyres are allowed during trials. The drivers must chose only one before the qualifications... And cannot change their mind.

The dimensions of the dry surface tyre are dictated above all by the maximum dimensions stipulated by regulations, but the Michelin engineers do not necessarily give preference to the greatest width possible: of course, the contact area would be considerably increased, but at 300 km/h, the time loss caused by a few unnecessary millimetres can be counted in tenths of seconds. This must be taken into account. Comprising more than one hundred ingredients, the compound is based on three main elements: carbon, oil and sulphur. More or less soft depending on the characteristics of each circuit, this sector changes considerably from one race to the next, whereas the structure evolves little by little throughout the season.

The whole thing operates at an optimal temperature of around 100° C, resulting from “centring” and should, in theory, be ideally distributed between the outside, the centre and the inside of the tyre tread. This temperature should also be identical from left to right, and from front to rear of the car. Too much heat at the rear? The car will tend to over-steer. Too much heat at the front? It will under-steer.

Measuring the tyre pressure as often as possible is also a priority. Although low pressure (of about 1.1 kg/cm2) allows the envelope to grip the track better and provides a greater contact area, a variation of just 0.2 kg/cm2 can “ruin” the performance of the car. In order to ensure the lowest possible variations in tyre pressure (heat increases the pressure), F1 tyres are filled with a special mixture.

Operating

The whole thing operates at an optimal temperature of around 100° C, resulting from “centring” and should, in theory, be ideally distributed between the outside, the centre and the inside of the tyre tread. This temperature should also be identical from left to right, and from front to rear of the car. Measuring the tyre pressure as often as possible is also a priority. Although low pressure (of about 1.1 kg/cm2) allows the envelope to grip the track better and provides a greater contact area, a variation of just 0.2 kg/cm² can “ruin” the performance of the car. In order to ensure the lowest possible variations in tyre pressure (heat increases the pressure), F1 tyres are filled with a special mixture.

Previous pictures show all three different types of tyres, and a worn tyre spec. From left to right are a Michelin raintyre, a Bridgestone intermediate, Bridgestone dry tyres and a worn dry spec Bridgestone tyre. Note that the worn tyre has almost no more visible grooves, which has been a fuss during the first years of the grooved tyre introduction. A rule existed that a car could be disqualified if at the end of use, a tyre's obliged grooves were less than 50% existent due to wear.

Wheels

F1 wheels are usually made from forged magnesium alloy due its low density and high strength. They are machined in one piece to make them as strong as possible, and are secured onto the suspension uprights by a single central locking wheel nut. This 'lock' is quickly pushed in to release the wheel during a pit stop, and the tyre changer then pulls it again to lock the wheel once the tyres have ben changed.

The teams buy wheels from companies such as OZ Racing, Enkei and Fondmetal. Once at the track, teams deliver their bare wheel rims to the tyre manufacturers truck where the tyres are put onto the rims with special machines. The tyres are then inflated and delivered back to the teams.

Wheel tethers

Since 1998, F1 cars have had to fit wheel tethers connecting the wheels to the chassis. This rule was introduced to try to stop wheels coming free and bouncing around dangerously during an accident. Unfortunately, wheels still do come off the cars during crashes, tragically killing a marshall at the Italian GP in 2000. The FIA have introduced an extra tether to each wheel for the 2001 season to try to stop the wheels coming off and causing injury to other drivers, marshals or spectators. The tether must attach to the chassis at one end, with the other end connecting to the wheel hub.

The wheel tethers are made by one of three companies in the UK, Future Fibres in London being one of them, and take the form of a rope. The tethers used in F1 are a derivative of high performance marine ropes, made especially for each car. They are made from a special polymer called polybenzoaoxide (PBO) which is often called Zylon. This Zylon material has a very high strength and stiffness characteristic (around 280GPa) much like carbon, but the advantage of Zylon is that it can be used as a pure fibre unlike carbon which has to be in composite form to gain its strength. The drawback of Zylon is that is must be protected from light, so it is covered in a shrink wrapped protective cover. The tethers are designed to withstand about 5000 kg of load, but often they can break quite easily during an accident, especially if the cable gets twisted by the broken suspension members. The teams normally replace the tethers every two or three races to ensure that they can withstand the loads put on them during an accident.

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