Setup Collaboration (grid-gp)

Reference Material

• RacerAlex Setup Guide
• f1technical.net

Much of the following is from the RacerAlex guide, modified for our GP cars.  Lots of verbosity in the form of physical descriptions of the parts has been removed.  Some theory has been removed, and incorrect theory (namely some aero) that is relevant to know has been corrected.

Aerodynamics

Not only is airflow crucial in generating downforce with the lowest possible drag coefficient, but also serves to cool several systems including brakes, engine and transmission. The most often adjusted aerodynamic items are the front and rear wings and car ride-height.

Wings

This airflow past wings creates its downforce at the cost of aerodynamic friction, or drag. The rear wing is always a compromise of rear downforce vs. top speed. High downforce settings produce serious drag, therefore greatly hindering the cars top speed. When setting rear wing angles, you should always try to obtain maximum rear downforce without impacting the cars ability to reach a competitive top speed. The front wings do not impact drag as much, even at their highest downforce settings. Therefore, the rule of thumb is to use as great a front wing angle as possible without upsetting the cars rear-end balance. While not done often, the both wings are adjustable during a pit stop.

Brake and engine cooling

Brakes and radiators require air at the cost of upsetting the airflow around the car and creating drag. Inside and slightly ahead of each hub/wheel assembly, are the brakes cooling ducts. These ducts are necessary to force cool air over the brake discs. They come in many variations in size. We’ll cover brake temperatures in the later section on brake wear. The car also sports twin radiators whose airflow entry is at the front of the sidepods. These openings can be made larger or smaller depending on the circuit and radiator size. The smaller the inlet, the less friction is created as airflow is allowed to pass along the cars slippery sculptured body pieces. As a side note: The engine runs the most efficiently at its optimum temperature of 105 °C.

Ride Height (rear diffuser)

Airflow underneath the car is another source of downforce, particularly at the rear of the car. The airflow close to the ground is meticulously channeled under and around the plank. This airflow, due to the small gap between the car and road is accelerated forming a low pressure zone. From here, the air expanded by means of the rear diffuser. The diffuser design calculates the amount of space underneath the car, then sculpts an exit of increasing spatial volume.

Much like an aircraft wing creates lift from low pressure by accelerating airflow over its tapered surface, the diffuser creates this low-pressure acceleration in front of the diffusor, and in the opposite direction, as the undercar airflow is literally pulled out from underneath. This suction causes downforce without any drag penalty. Therefore it’s very, very efficient.

One misconception is that the diffusor is where the downforce is centered, but really the downforce is centered where the low pressure is, which is where the air is flowing fastest, which is in front of the diffusor.  The diffusor being bigger helps by making the exit of the air more efficient, allowing more vacuum in front of the diffusor.  This distinction in where the center of downforce is is important because it matters with respect to aerodynamic balance.  This low-pressure downforce increases as the ride height decreases. This is why we want to run the car as low to the ground as possible without drastically affecting plank wear. Ride height is initially dictated by spring rates, which themselves are selected for handling characteristics. Then the cars ride height is fine-tuned by the ride-height adjustments on the suspension push rods. 

Suspension

“In motor racing, including Formula 1, you must always reach a compromise between the various settings which affect the performance of the car. There is no clearly defined procedure that will allow you to find the most effective setup in a scientific and dependable way” – Ayrton Senna, Principles of Race Driving

It’s vital to make a point at this time.  When adjusting suspension components, more so than at any other time, you really are balancing understeer and oversteer from all 4 corners of the car. Because the springs and dampers affect weight transfer, it is possible to dramatically, and directly affect the front of the car by adjusting the rear. And vise versa. Because of the complexity of the suspension, it’s important that you fully understand all the components and their specific purposes.

Springs

Springs store energy by absorbing or deflecting force. That is, when weight is transferred, the resulting energy is stored temporarily within the springs of the car until the weight is returned to its static state. At this point, the springs merely store the energy resulting from the car’s weight under the force of gravity.

The spring’s main function is to suspend the cars mass (thus being called “sprung mass”) while establishing a basic ride height, absorbing bumps and undulations, and controlling the motion of the vehicle under weight transfer during acceleration, braking, and cornering. These are critical functions, as due to the increasing influence of modern aerodynamics, any drastic changes to the car’s pitch and attitude will disrupt the aerodynamic downforce and overall efficiency.

Dampers

Dampers, or shock absorbers, are oil-filled cylinders which control the movement of the springs travel.  The kinetic energy from the piston movement is damped into the oil, resulting in increased heat.

Dampers control the way the springs react in the transition of loading and unloading energy. Example: under severe braking, the front-end pitches down, and front ride height decreases under weight transfer. While the springs dictate the amount that the nose pitches down, the dampers control the rate at which the pitch occurs. And of course, this applies to all transfer of weight during acceleration, braking and cornering.

Dampers on an GP car are 4-way adjustable. You may adjust the slow and fast response of the “bump”movement (energy loading into the springs), and the slow and fast response to the “rebound” movement (energy unloading out of the springs). The terms fast and slow do not correlate to the speed of the car, but rather the speed of the piston’s travel within the cylinder under the force of the push rod’s energy transfer. An easy method to analyze this is as follows: slow damping affects the weight transfer of the cars sprung mass (chassis pitch and roll) on the springs; fast damping controls the springs response to the deflection of the cars unsprung weight (the tire/wheel/hub assembly reaction to bumps). In other words, slow fine-tunes the cornering balance, fast fine-tunes the cars ability to handle over bumpy surfaces.

Dampers are the most finely tuned adjustments made to the suspension. The dampers should be the finishing touches to a well-crafted car setup. Because the nature of the dampers is so critical to the ultimate performance of the racecar, I suggest reading as much as possible on this topic.

Packers

Packers are composite “spacers” placed on the piston rod of the dampers. The packers are a last ditch effort to keep the plank underneath the car from being damaged. When the suspension push rod moves up with extreme force, compressing the spring and dampers to their maximum, the packer stops the travel of the suspension by impacting the damper cylinder body and the bump rubber. If you look closely at the picture on the previous page, you’ll see the packers are free to move along the damper piston rods.

Anti-Roll Bars

So far, the springs, dampers, and packers are grouped where each wheel/tire has independent control. And even though all 4 corners of the car are completely independent, most adjustments to these components are made symmetrically, with both left and right front spring/damper settings adjusted the same and both left and right rear spring/damper settings adjusted the same. This way, they handle the transfer of weight from front to back very efficiently, and handle bumps at each wheel extremely well. But, weight transfer from inside to outside during steady state cornering is not yet at maximum efficiency. The inside tires lose traction while the outside tires load-up during cornering. This is where anti-roll bars come into play.

How it all works together

All of these components work together create mechanical grip. Remember the objective it to get the tires up to their optimum operating temperature so they can produce their maximum grip. Those temperatures are a direct result of the weight loaded into the tire. While mechanical grip does assist the dominant aerodynamics at high speeds, it really contributes greatly at lower speeds when aerodynamic downforce is less influential. Here’s how the suspension contributes to mechanical grip:

1. The springs establish a basic ride height and mechanical grip balance from front to rear.
2. As the car brakes for a turn, lighter rear springs efficiently deal with the transferring weight from the rear, allowing the suspension to maintain some rear-end grip by not fully unloading the tires. The dampers control the springs transition and reactions from sudden bumps that may upset that the spring’s ability to transfer this weight.
3. On initial turn-in, the dampers continue to control the transition of the springs as the weight transfer shifts from inside to outside on the chassis
4. As the car transits from turn-in to steady state cornering, the anti-roll bars limit the chassis roll from inside to outside, thus reloading the inside tires with weight.
5. As the car approaches the exit of the turn, the anti-roll bars begin releasing their energy, placing the weight transfer back onto the springs under the control of the dampers.
6. On exit as power is reapplied to the rear tires, the weight transfers to the rear. The softer rear springs now allow the rear to absorb that energy quicker and apply it towards maximum traction under acceleration.

Note: A compromise must always be obtained when setting up the car.  Example: Damper values set too high when using soft spring rates will negate the spring rate all together as they will control the loading to such a degree as the spring never fully loads, or to a more detrimental degree unloads more rapidly. All components should work together, each one doing its specific part, and it’s this synergy that allows the most efficient handling of weight transfer over the various attributes of the given circuit.

Third Springs

Third springs were created for cars with high downforce. The strategy is to run a third spring and/or damper on either axle, in order to separate out roll characteristics from those controlling vertical motion. This permits single-wheel motion to have a relatively soft spring rate, whereas moving both wheels at the same end in the same direction, say up, causes the 3rd spring to be compressed so the effective spring rate at the wheel appears to be much higher. This permits improved control over ride height and hence downforce, and improved handling.

By using a 3rd spring, it is possible to achieve stiffer suspension whilst the car's tyres are being displaced by the same amount (eg. traveling down a straight), yet at the same time it is possible to still reap the benefits from a softer suspension setup whilst cornering (bump or rolling motion).

When both tyres are displaced by the same amount (as they would through aerodynamic forces pushing the car down on the straight), all 3 springs/dampers work together, providing a very stiff system.

When only one tyre is displaced only the spring/damper that corresponds to that wheel is worked. 

Tires

The optimum tire temperature for our GP tires is 105C. The general rule is the softer the compound, the higher the tyres' grip level. But the softer tyre is more susceptible to heat therefore increased wear.

Because the tyres are the cars sole contact patches with the track, we can learn a wealth of information by taking temperature readings from each tyre throughout a session. This is the single most important physical indicator of what the suspension is doing. These readings are taken from three locations across the tyre tread: inside edge, middle, and outside edge. Using these readings, you can accurately set up the tyres camber angle adjustments and tyre pressure, as well as getting indications as to the efficiency of your spring rate and damper choices. When all temperatures across a specific tyre are equal, this indicates the tyre contact patch is averaging flat against the track over a lap. 

The tyres will achieve maximum grip when run at their associated optimum running temperatures. The higher the temperatures, the more loading under weight transfer that tyre is experiencing. The lower the temperature, not enough weight is being loaded into the tyre (or too much weight is being unloaded from that tyre).

Camber and Tire Pressure

Camber adjustments and tire pressure settings allow us to fine-tune the tire contact patch to the road surface. The camber adjustment fine-tunes how flat the tires contact patch is to the ground by tilting the top of the wheel/hub assembly towards or away from the chassis. With this in mind, the camber helps us even out the individual tire wear based on temperature readings from the tires inside and outside edges.

Negative camber is when the top of the wheel/tire assembly leans in towards the car. Under nominal conditions, this extreme amount of negative camber setup will heat the inside edges of the tires prematurely and yield uneven tire wear plus less than the maximum amount of mechanical grip. However, some degree of negative camber is the most efficient setting for maximizing tire grip. As the car turns-in with a slight amount of chassis roll, weight is transferred to the outside tires. The outside tire bears the majority of the load during cornering. Negative camber helps the outside tires move into a more perpendicular position under this weight transfer.

The amount of laps and how hard the car was pushed should always be taken into consideration when taking tire temperature readings. A setup with negative camber will be heating up tires inside edges under straight-line running. However this heat (tire wear) is insignificant to the amount of heat built-up during hard cornering. Still, it raises an interesting observation. Should you apply negative camber to a setup, then go out and run two laps at 80% of the cars ability (not really pushing it), your temperature readings might prove false information by showing hotter inside temps than when the car is being pushed hard. For best results, you should run at least three laps at 95% of the cars ability before expecting conclusive temperature readings.

Tire pressure is the way to increase or decrease the middle temperature reading (at the tires ‘crown’) on each tire relative to the edges.  The sidewall of a racing tire is fairly stiff, so if tire pressure is low, the tire tends to bulge in the sides (where it begins to bare the static weight of the car) and pull the middle of the treads crown inward towards the wheel rim. In this condition, the outside edges heat up more than the inside since they’re contacting the road more than the center. Likewise, if the tire is over-inflated, the middle of the tires crown will protrude outward further than its two edges. In either case, if the tire is not flat against the track, the point that impacts greatest will generate higher temperatures under increased friction. The result is less grip, more wear.

All this factors into the suspension settings as well. If we are to lower the spring rates, then it will effect the camber adjustments. Since the softer springs absorb more weight, the static ride height lowers. Under the suspension compression, the tires begin to lean in as the wishbones move up. This in turn causes the need for a camber adjustment to counter the effects and place the tires back perpendicular to the road surface. The process continuously cycles through. But don’t worry, as you get the car closer and closer to your liking the changes will become smaller and smaller.

“The aim of a driver and his team in setting up the car is to ensure that the tyres operate in the best possible conditions. Only in this way will a tyre, which is one of the fundamental components of a Formula 1 car, perform to the limit of its potential” – Ayrton Senna, Principles of Race Driving

Toe-in

Toe is the static angle of the wheels, as seen from above, as to whether they point in (leading edge towards the car, which is negative or toe-in) or out (leading edge away from the car, which is positive or toe-out). The reason most cars have a bit of front negative toe, or toe-in, is to promote straight-line steering stability. If a car was to have 0-degree toe it would be very nervous on a straight road, wanting to dart and wander at any little bump, rut or groove. By adding toe-in (negative toe), each wheel attempts to turn the car “inward” at all times. This in turn creates that centering feel we have through the steering wheel and promotes better straight-line stability.

Rear toe is a highly debated topic. On the negative side, critics claim rear toe only adds to increased and uneven tire wear. And this comes with no discernable performance advantage. On the positive side, pundits claim a slight positive toe, or toe-out, at the rear can help stabilize the rear of the car under acceleration.

But be mindful; too much negative toe-in will heat the outside edges of the tires, creating friction and affecting speed to a small degree. Excessive toe-out meanwhile will heat the tires inside edge. You should counter these reactions with small camber adjustments.

Weight Distribution

When mass is shifted fore or aft that mass does indeed apply more download towards that end of the car. However, it also increased the sideload demand of the tires, which means those tire need more grip. So you get more, but you need more. If the additional amount of grip you get outweighs the additional amount you require, then you shift the balance more in that direction and visa versa. 

Braking System

The braking system of a GP car is a conventional hydraulic pressurized piston, pad, and disc system.

Brake Pressure

Higher brake pressure means more maximum braking potential, but more difficult modulation.  Too much brake pressure throws away modulation (basically at whatever position the pedal is at at a given instance to cause lockup, any pedal left is wasted with respect to modulation).  Too little brake pressure throws away braking capability (whenever you are at full pedal but are not locking up yet, you are wasting braking capacity).

Brake Bias

Since the performance of a BP car is based on it’s ability to exploit weight transfer, it is necessary to alter the braking balance of the car. When we alter the braking balance, we’re merely shifting the force of the brakes so as half the car experiences more stopping power to the wheels than the other. The half we always shift towards is the front for the simply reason that weight transfers to the front under braking. We compensate because without this shift in bias, the transfer tends to makes the rear tires less tractable.

With 50/50 braking bias, the rear wheels will lock prematurely as the weight shifts away from them under braking causing the car to oversteer during corner entry. The rule of thumb is to set the greatest amount of front bias without locking the front wheels under nominal braking conditions. Shifting this forward however will increase the cars tendency to understeer on corner entry.

Brake Heat

A common braking system problem is fade brought on by excessive heat.

Brakes require a certain temperature to operate at maximum efficiency. Cold brakes do not have the stopping force of a heated disc. At optimum temperature the brake will produce the most amount of stopping force. However, since the stopping friction creates heat, heat then turns into a detriment, causing “brake fade”, or reduced stopping force. Running the brakes at close to their optimum temperature is crucial. Altering the brake cooling duct sizes controls this.

Note that brake bias can dynamically change when the brakes are outside of their optimum range. For example, if your front brakes overheat, but your rear brakes are still at optimum temp, then you'll result in a possibly massive brake bias shift rearwards.

Transmission

grid-gp drivelines

• helotek – 5 speed pure RWD
• gyrotek - 5 speed anti-spin semi-AWD via plate diffs
• as2 -- 5 speed anti-spin semi-AWD via viscous diffs

Gearing

When selecting gear ratios, two factors control the first decision: what are the circuits expected top speed and what is the slowest corner on the racecourse. The latter most of the time is a second gear corner so we’ll initially focus on second gear and then the fifth gear. After establishing those ratios, we will even space the remaining 3rd and 4th gears for maximum and even acceleration up to the top speed

If the circuit has a hairpin (like Magny-Cours in France) then sometimes 1st gear will be chosen for dependable navigation of that corner. If the slowest corner is a 2nd gear corner, then first gear is selected solely for the start of the race. Even then, certain factors play a role in making the ratio selection. The initial selection should be made for maximum acceleration up to 2nd gear from a flat starting grid position. If the qualified grid position is on a decline, one might want to shorten the ratio by 1 increment. If the qualified grid position is on a slight incline, the opposite would be true. With the advent of launch control systems, it is less crucial to set this, but none the less it makes good sense to better the cars performance in any way possible.

Differential (gyrotek and as1)

For these semi-AWD drivelines, the anti-spin setting are what matter most, and they simply set how readily excess torque transfers between the rears and fronts during forward (throttle) or backwards (brake) load.  0% approches how a helotek might feel, although without the pump and coast control that the helotek has.

Differential (helotek)

The differential is the mechanical coupler between the transmission output and the driveshafts of the rear wheels and in an GP car is integrated into the gearbox itself. This is where the engines crankshaft rotation, after being applied through the clutch and specific selected gear, is transferred by the associated final drive gearing ratio to the drive wheels.

“To assist in the process of setting up the car for a circuit a driver has to use all his powers of concentration. First of all, he has to tackle each corner in three stages. Then, once he has to establish reference points and the correct racing line, he should try to stick to them as closely as possible. Varying the line from one lap to the next alters the cars behavior and creates extra problems. As soon as a driver has got to grips with a circuit, he should be able to complete a lap in the same fashion time after time. If each lap follows the same pattern, the driver is better able to analyze events objectively. Indeed, such consistency makes the driver a reference point himself. This requires much attention to detail, but by maintaining the same procedure for lap after lap you become a good test driver” – Alain Prost and Pierre-Francois Rousselot, Competition Driving

Note: copied from an rscnet forum post. 

Differential Pump

This is the setting you all are most familiar with. Diff Pump works just like a viscous differential coupling, with spinning plates and a viscous fluid.

The HowStuffWorks explanation: The viscous coupling has two sets of plates inside a sealed housing that is filled with a thick fluid, as shown in below. One set of plates is connected to each output shaft. Under normal conditions, both sets of plates and the viscous fluid spin at the same speed. When one set of wheels tries to spin faster, perhaps because it is slipping, the set of plates corresponding to those wheels spins faster than the other. The viscous fluid, stuck between the plates, tries to catch up with the faster disks, dragging the slower disks along. This transfers more torque to the slower moving wheels – the wheels that are not slipping. When a car is turning, the difference in speed between the wheels is not as large as when one wheel is slipping. The faster the plates are spinning relative to each other, the more torque the viscous coupling transfers. The coupling does not interfere with turns because the amount of torque transferred during a turn is so small. However, this also highlights a disadvantage of the viscous coupling: No torque transfer will occur until a wheel actually starts slipping.

You'll see in telemetry that setting this to 100% does not mean that your rear wheels are firmly locked together, but it does offer a nice stabilizing force in yaw and generally better traction while accelerating. The downside of a higher setting can be understeer and you may not like how the chassis loses some of it's responsiveness.

This setting can be used alone to set up your differential (after all this is the only setting available with the standard F1 cars). It is highly advised that you use Diff Pump in conjunction with PowerSide and CoastSide as there are some shortcomings of those two settings with respect to the ramp angle&clutch pack setup you may be familiar with from GPL. In this case you can kinda treat Diff Pump as the clutch pack to smooth the action from one side to the other.

Differential Power Side

This setting, together with Coast Side, work somewhat like the ramp angles of a typical clutch plate differential. The simplest way to describe how it works is that if a different amount of torque is being applied to the drive wheels, the differential will transmit a certain percentage of that difference through the axles in attempt to equalize the driving/braking torque on either side of the car. Still not so simple an explanation, eh? Think of it in cause and effect then: Setting the power side to 100% means that, when you are on the gas, the rear wheels lock together. A setting of 0% means that power will follow the path of least resistance and you'll get a one-wheel burnout (much like in an open differential). Anything in between will give you…well something in between.

Differential Coast Side

Works just like Diff Power Side, except under braking torques rather than power. Most effective at controlling how the car behaves during turn in, as you are usually still braking somewhat while doing that. Higher settings will feel more stable but cause understeer. Too low a setting can allow the car to violently snap away from you during braking.

Differential Preload

Diff Preload is something like a clutch that must be disengaged before wheelspin can occur. Higher settings mean that a larger difference in wheel torques must be present before any wheelspin, and thus differential action, happen. For the Sport35L cars this has little effect, but will be more important in later addon cars which sometimes ran a spool - locked - differential for added stability. In those cases there will only be two settings available: 0 - typical parasitic locking caused by friction of parts. Relatively small and wheelspin will easily begin 1 - Spool diff. No way will you reach the preload value and the rear wheels will be solidly locked together. Can give stability at the cost of understeer and very likely will completely change the driving characteristics of the car.