iRacing IR18 Dallara User Manual

iRacing IR18 Dallara

Dear iRacing User, Congratulations on your purchase of the Dallara IR18! From all of us at iRacing, we appreciate your support and your commitment to our product. We aim to deliver the ultimate sim-racing experience, and we hope that you’ll find plenty of excitement with us behind the wheel of your new car! American open-wheel’s latest generation car, the Dallara IR18, was designed to not only look better on track but also improve the racing. All cars in this series will race with the same aero kit, designed and built by Dallara, regardless of the engine manufacturer they choose. This will make for closer racing, more opportunities for on-track passes, and more exciting races overall. It features two distinctly different aero packages – one low downforce package for super speedways like Indianapolis and another high downforce package for street and road courses. Under the hood, the power plant remains at a 2.2 liter turbocharged V6 that produces upwards of 700 bhp. The following guide explains how to get the most out of your new car, from how to adjust its settings off of the track to what you’ll see inside of the cockpit while driving. We hope that you’ll find it useful in getting up to speed. Thanks again for your purchase, and we’ll see you on the track!

Introduction

The information found in this guide is intended to provide a deeper understanding of the chassis setup adjustments available in the garage, so that you may use the garage to tune the chassis setup to your preference. Before diving into chassis adjustments, though, it is best to become familiar with the car and track. To that end, we have provided baseline setups for each track commonly raced by these cars. To access the baseline setups, simply open the Garage, click iRacing Setups, and select the appropriate setup for your track of choice. If you are driving a track for which a dedicated baseline setup is not included, you may select a setup for a similar track to use as your baseline. After you have selected an appropriate setup, get on track and focus on making smooth and consistent laps, identifying the proper racing line and experiencing tire wear and handling trends over several laps. Once you are confident that you are nearing your driving potential with the included baseline setups, read on to begin tuning the car to your handling preferences.

GETTING STARTED

To start the car turn on the Ignition and then press and hold the starter button until RPM rises above 3000rpm, after which the starter can be released. To leave the pits depress the clutch (if Auto-Clutch is not in use), press “upshift” to put the car in gear, and apply the accelerator pedal while slowly releasing the clutch. Once the car is in motion, all shifting is clutchless and doesn’t require manual throttle cuts for upshifting or downshifting. Upshifting is recommended around 12,000rpm, once all shift lights are illuminated.

LOADING AN iRACING SETUP

Upon loading into a session, the car will automatically load the iRacing Baseline setup [baseline.sto]. If you would prefer one of iRacing’s pre-built setups that suit various conditions, you may load it by clicking Garage > iRacing Setups > and then selecting the setup to suit your needs. Due to this car utilizing multiple packages for various track characteristics, some setups may fail tech if loaded at a track which the setup was not built for. If you would like to customize the setup, simply make the changes in the garage that you would like to update and click apply. If you would like to save your setup for future use click “Save As” on the right to name and save the changes. To access all of your personally saved setups, click “My Setups” on the right side of the garage. If you would like to share a setup with another driver or everyone in a session, you can select “Share” on the right side of the garage to do so. If a driver is trying to share a setup with you, you will find it under “Shared Setups” on the right side of the garage as well.

Dash Pages

The Dallara IR18 features a dash display built into the steering wheel with two display pages, each showing different data values that may be relevant in racing conditions. The steering wheel also features a row of lights to aid in shift timing and two clusters of LED lights to notify the driver of yellow- flag conditions.

LED INDICATORS

SHIF T LIGHTS
The uppermost row of LED lights above the display are shift lights linked to engine RPM. As RPM approaches the maximum, the lights will begin to illuminate left to right starting with green, then yellow, then red. Once all ten lights have illuminated and RPM climbs further, the lights will turn blue and begin flashing to signal an upshift is necessary.

TRACK/STATUS LIGHTS
If a Caution period begins, the two clusters of three LEDs on either side of the main display will illuminate in yellow. If a critical engine situation occurs, the right set of lights will illuminate in red and a message showing the problem will appear on the main display within a red border.

• DASH CONFIGURATION
  The first page of the display is primarily a screen displaying timing information as well as some information about the car’s configuration and status.

• Dist Car Forward In Race sessions, this will display the gap to the car one position ahead in seconds.

• Dist Car Behind In Race sessions, this will display the gap to the car one position behind in seconds.

• Fuel Remaining The amount of fuel remaining in the fuel tank is displayed here in either US Gallons or Liters depending on the measurement system chosen in the garage.

• RPM The engine RPM is displayed at the top of the display in the center.

• Gear Indicator The currently selected gear is displayed in the center of the display below the RPM.

• Lap Count The number of laps completed.

• Lap Time The previously completed lap time. If no lap has been recorded, the display will show 1 second.

• Lap Diff The difference between the current lap’s pace and the session’s best recorded lap will be shown below the Lap Time.

• FARB The currently selected position of the front ARB arms is shown in the left red box on the bottom of the display.

• RARB The currently selected position of the rear ARB arms is shown in the right red box on the bottom of the display.

• P2P For Practice sessions, the P2P box displays the number of times Push-To-Pass has been activated during the session. For Race sessions, the display will begin at 10 and is reduced by one each time the Push-To-Pass system is used during the race. Once the counter reaches zero, the system cannot be activated again.

• Fuel Pos The currently selected engine map.

• MPG/LPL Fuel economy is displayed in an orange box on the bottom of the display. The value shown will be dependent on the unit system chosen in the garage, with Imperial units displaying Miles per Gallon

• (MPG) and Metric showing Liters per Lap (LPL).

• POS Current session position.

DASH CONFIGURATION

Page 2 of the display shows information relevant to the car’s operation, useful in diagnosing issues if they arise. Units for these values are dependent on the unit system chosen in the garage.

• Oil Temp The temperature of the engine oil, in Fahrenheit (°F) for Imperial and Celsius (°C) for Metric.
• Oil Press Pressure in the engine oil system, in Pounds per Square Inch (psi) for Imperial and Bar for Metric.
• Brake Bal The current brake bias, displayed in the percentage on the front axle, is shown in the bottom left of the display.
• RPM The engine RPM is displayed at the top of the display in the center.
• Gear Indicator The currently selected gear is displayed in the center of the display below the RPM.
• Water Temp The temperature of the water in the engine’s cooling system, in Fahrenheit (°F) for Imperial and Celsius (°C) for Metric.
• Fuel Press Pressure in the fuel system, in Pounds per Square Inch (psi) for Imperial and Bar for Metric.
• Battery The voltage output of the battery is shown in the bottom right.

CONDITIONAL SCREENS

PIT LIMITER
When the Pit Limiter is active all of the shift lights will flash in blue and the display will have a yellow border:

PUSH-TO-PASS
When Push-to-Pass is active, the inner pairs of status LEDs will illuminate in green and the display will have a green border:

CONDITIONAL SCREENS

To improve driver visibility, the center support pillar for the Aeroscreen can be removed via the “Hide Obstructions” setting in the Options menu. To enable this option go to the Options and then Graphics menu, then change the “Hide Obstructions” setting to either “Cockpit halo” or “All”. This will set the center pillar to a transparent version.

Advanced Setup Options
This section is aimed toward more advanced users who want to dive deeper into the different aspects of the vehicle’s setup. Making adjustments to the following parameters is not required and can lead to significant changes in the way a vehicle handles. It is recommended that any adjustments are made incrementally and only singular variables are adjusted before testing changes.

Tires & Aero

TIRE COMPOUND

TIRE COMPOUND
Air pressure in the tire when the car is loaded into the world. Higher pressures will reduce rolling drag and heat buildup but will decrease grip. Lower pressures will increase rolling drag and heat buildup but will increase grip. Higher speeds and loads require higher pressures, while lower speeds and loads will see better performance from lower pressures. Cold pressures should be set to track characteristics for optimum performance. Generally speaking, it is advisable to start at lower pressures and work your way upwards as required.

TIRE SETTINGS (ALL FOUR)

COLD PRESSURE
Air pressure in the tire when the car is loaded into the world. Higher pressures will reduce rolling drag and heat buildup, but will decrease grip. Lower pressures will increase rolling drag and heat buildup, but will increase grip. Higher speeds and loads will require higher pressures, while lower speeds and loads will see better performance from lower pressures. Minimum pressures will change based on track type, with ovals typically having a higher right-side minimum tire pressure than the left-side tires.

LAST HOT PRESSURE
Air pressure in the tire when the car is loaded into the world. Higher pressures will reduce rolling drag and heat buildup, but will decrease grip. Lower pressures will increase rolling drag and heat buildup, but will increase grip. Higher speeds and loads will require higher pressures, while lower speeds and loads will see better performance from lower pressures. Minimum pressures will change based on track type, with ovals typically having a higher right-side minimum tire pressure than the left-side tires.

LAST TEMPS O.M.I.
Air pressure in the tire when the car is loaded into the world. Higher pressures will reduce rolling drag and heat buildup but will decrease grip. Lower pressures will increase rolling drag and heat buildup but will increase grip. Higher speeds and loads will require higher pressures, while lower speeds and loads will see better performance from lower pressures. Minimum pressures will change based on the track type, with ovals typically having a higher right-side minimum tire pressure than the left-side tires.

TREAD REMAINING
Air pressure in the tire when the car is loaded into the world. Higher pressures will reduce rolling drag and heat buildup but will decrease grip. Lower pressures will increase rolling drag and heat buildup but will increase grip. Higher speeds and loads will require higher pressures, while lower speeds and loads will see better performance from lower pressures. Minimum pressures will change based on the track type, with ovals typically having a higher right-side minimum tire pressure than the left-side tires.

WING ENDPLATE ANGLE
The wing endplate assembly can be rotated relative to the wing mainplane up to 3° positive or negative. Higher Wing Endplate Angles will increase downforce and shift aero forward, but also change what Wing Mainplane angles are available. Higher Endplate Angles will allow for higher Wing Mainplane angles (but also a higher minimum angle) while lower Endplate Angles will allow for much lower Mainplane angles. This option is not available for Road Courses and Short Ovals.

WING ANGLE
The Wing Angle setting changes the angle of the front wing’s mainplane relative to horizontal. Higher angles will increase the downforce generated at the front wing, shift aero forward, and increase drag, while lower angles will decrease downforce, shift aero rearward, and reduce drag. Depending on the chosen Wing Endplate Angle, it is possible to run negative front wing angles. These settings still produce some downforce, but greatly reduce drag for high- speed ovals such as Indianapolis.

FRONT AERO

WING FL AP CONFIG
The number of front wing upper flaps is mandated per series rules based on the track type. For Road Courses the wing will have two upper flaps and for Ovals the front wing will have one upper flap.

WING MAINPL ANE EXT
The Wing Mainplane Extension adds small elements to the front wing’s mainplane to increase downforce generated by the wing assembly. Changing this setting to “ON” will increase Front downforce and slightly increase drag, while setting this to “OFF” will shift aero balance rearward and decrease drag slightly. See the “Wing Wicker” section for more information on this feature.

WING WICKER
A small wicker (or “Gurney Flap”) can be added to the trailing edge of the front wing upper-most flap. The options available for this setting are track dependent:

• Road Course – A single wicker on the uppermost front wing flap is allowed
• Large Oval, no Wing Mainplane Extension – A wicker may be added to the front wing trailing edge. The wicker can be added in “Steps”, with each step indicating how many thirds of the front wing span has a wicker on it. For example, the Step 2 wicker will cover ⅔ of the front wing span, Step 3 will be a full-span wicker.
• Large Oval, Wing Mainplane Extension – If the Wing Mainplane Extension is installed, Steps 2 and 3 are not an option. If no wicker is chosen, the Wing Mainplane Extension will span the inner half of the front wing. If the Step 1 wicker is chosen, an outer extension and wicker will be installed, creating a full-span Mainplane Extension with a small wicker on the outer half.
• Short Oval -Wicker not allowed.

WING ENDPLATE ANGLE
The wing endplate assembly can be rotated relative to the wing mainplane up to 3° positive or negative. Higher Wing Endplate Angles will increase downforce and shift aero forward, but also change what Wing Mainplane angles are available. Higher Endplate Angles will allow for higher Wing Mainplane angles (but also a higher minimum angle) while lower Endplate Angles will allow for much lower Mainplane angles. This option is not available for Road Courses and Short Ovals.

WING ANGLE
The Wing Angle setting changes the angle of the front wing’s mainplane relative to horizontal. Higher angles will increase the downforce generated at the front wing, shift aero forward, and increase drag, while lower angles will decrease downforce, shift aero rearward, and reduce drag. Depending on the chosen Wing Endplate Angle, it is possible to run negative front wing angles. These settings still produce some downforce, but greatly reduce drag for high- speed ovals such as Indianapolis.

BODY AERO

RADIATOR INLET
Both sidepod inlets can be blocked off partially to decrease drag when desired. Decreasing the opening size (More “closed” percentage in the garage setting) will reduce drag with a slight reduction in downforce, but will increase engine temperatures due to reduced cooling. The 77% Closed option is only available for Qualifying sessions and is not allowed for Race sessions.

TRAILING EDGE WICKER
A 1” tall wicker can be installed on the upper edge of the rear diffuser at Road Courses and Short Ovals to increase downforce and shift aero rearward, but will increase drag. This option is not available for Large Ovals.

DIFFUSER
The rear diffuser assembly can be customized via three options:

• Sidewalls – The outermost walls of the diffuser can be installed, removed, or trimmed to change the overall downforce and drag produced by the diffuser. Removing the sidewalls will reduce drag with a large reduction in downforce. “Trimmed” sidewalls are partially-removed sidewalls and provide more downforce than “OFF”, but less than “ON”.
• Strakes – The diffuser can be fitted with internal vertical Strakes to increase the diffuser’s efficiency and downforce produced. Installing the diffuser strakes will increase downforce and drag. A third option, “Z+15” installs a 15mm extension to the bottom of the diffuser strakes to further increase downforce.

For Large Ovals the options for the diffuser are mandated so that both the Sidewalls and Strakes are off..

REAR AERO

WING FL AP CONFIG
For Road Courses, the rear wing can be configured with one or two upper flaps. The Double Plane configuration will generate a significant amount of downforce and shift aero rearward at the cost of high drag, while the Single Plane option will greatly reduce both downforce and drag but shift aero forward. For ovals, only the Single Plane option is available.

WING ANGLE
The Rear Wing Angle setting controls the angle of the rear wing’s uppermost flap. Higher angles will produce more downforce, more drag, and shift aero rearward, while lower angles will reduce both downforce and drag but shift aero forward. Available wing angle ranges will change based on the wing assembly (Road Course/Short Oval or Large Oval) as well as the number of flaps chosen in the Flap Config setting.

WING WICKER
A trailing edge wicker may be installed on the rear wing for most tracks. This adds downforce and shifts aero rearward but adds drag. The rules on what can be used are track-dependent:

• Road Course / Short Oval – Can be run without a wicker or with a full-span ⅜” wicker
• Large Ovals (except Indianapolis) – Rear wing wicker is not allowed.
• Indianapolis Motor Speedway Oval – A wicker can be installed on the rear wing at Indianapolis that is ⅜” tall but has various widths of 13.2 inches, 24.5 inches, or a full-span wicker. This wicker is situated on the centerline of the wing and extends equally on either side of the centerline. This wicker can be removed as well, such as in Qualifying when opting for a very low-drag configuration.

AERO CALCULATOR

The Aero Calculator is a quick way to get a general idea of the car’s aero balance in the current configuration. Once the Front, Body, & Rear Aero settings have been chosen, the front and rear ride heights and the chassis roll can be set to find the car’s aero balance and Downforce-to-Drag ratio. This is very helpful for planning setup changes to either keep the same aerodynamic balance after a change or to understand how much the balance will shift with changes. Please note the settings chosen in this area of the garage do not affect the setup or on-track performance and are simply a way to understand how the car is performing.

AVG FRONT / REAR RH AT SPEED
The Ride Height (RH) at Speed settings are inputs for the aero calculator to determine the approximate aero performance with the chosen aero package. Changing these values changes the displayed Front Downforce value as well as the Downforce-to-Drag ratio in the calculator. To check on-track performance, use the average of the front ride height sensors (Front RH) and the average of the rear ride height sensors (Rear RH) from telemetry. These can also be changed to observe how rake will affect aerodynamic performance prior to ride height or spring changes.

AVG TILT AT SPEED
The Tilt at Speed setting is a value of how much the chassis is rolled left or right. For best results, calculate (from on-track telemetry data) an average of the left-side ride heights and an average of the right-side ride heights. The difference between these averages is the Tilt-at-speed value to use in the calculator.

AERO BALANCE
Aero Balance represents the percentage of total downforce that is working on the front axle. This value is calculated with the At Speed ride height and tilt values, as well as the chosen aerodynamic options, and should be monitored during the chassis setup process to prevent unexpected results. To ensure chassis adjustments don’t become masked by aerodynamic changes, always refer to this value to ensure it remains constant before and after aerodynamic setup changes.

DOWNFORCE TO DRAG
The Downforce to Drag ratio is a relation of how much downforce is produced for one unit of drag. Generally, a larger downforce-to-drag ratio would imply the car is working efficiently and producing large amounts of downforce for given drag numbers, while a lower Downforce to Drag value is typically seen on more slippery, low-drag aerodynamic packages.

Chassis

GENERAL

WHEELBASE
For some track configurations the overall wheelbase can be adjusted to change the car’s handling behavior and responsiveness. On Large Ovals and Indianapolis, the wheelbase can either be set to 121 or 119 inches. The longer option will result in a more directionally-stable car that is less responsive, but less sensitive to aero balance and longitudinal weight shifting. The shorter option will be more responsive, which is good for tighter corners, but will be more sensitive to fore-aft aero and weight shifting. For Road Courses and Short Ovals, the only option available is the 121 inch setting.

BRAKE PRESSURE
If overall downforce is increased or decreased, the overall braking pressure may need to be changed to suit. Generally, higher downforce levels can use higher braking pressures without wheel lockups, while lower downforce levels will need reduced brake pressures.

BRAKE PRESSURE BIAS
The Ride Height (RH) at Speed settings are inputs for the aero calculator to determine the approximate aero performance with the chosen aero package. Changing these values changes the displayed Front Downforce value as well as the Downforce-to-Drag ratio in the calculator. To check on-track performance, use the average of the front ride height sensors (Front RH) and the average of the rear ride height sensors (Rear RH) from telemetry. These can also be changed to observe how rake will affect aerodynamic performance prior to ride height or spring changes.

STEERING PINION
To fit various driver preferences, the Steering Pinion can be changed to alter how fast or responsive the steering is. Higher pinion teeth numbers will result in a faster steering response which can make the car feel more twitchy with small steering inputs, while lower pinion values will slow the steering and make it less responsive to inputs.

STEERING OFFSET
On oval tracks it’s not uncommon for the chassis to be set up asymmetrically, causing the car to pull to one side and the driver to hold some amount of opposite steering to counter it. If desired, the Steering Offset setting can be changed to center the steering wheel down the straights. Positive values will reposition the steering wheel in a clockwise direction, negative values will position the steering wheel in a counter-clockwise direction.

NOSE WEIGHT
Nose Weight is the percentage of the vehicle’s total weight that is situated on the front axle. This is used primarily to balance front-to-rear aero distribution, and in most cases will produce a directionally stable car when set higher than the aero balance percentage. Less Nose Weight will shift weight rearward, inducing oversteer as well as helping the car change directions more easily. More Nose Weight will create a more directionally stable chassis but can induce understeer if set too far forward.

GROSS WEIGHT
Crossweight is the percentage of the car’s total weight situated over the Right-Front and Left-Rear wheels. For the IR18, this value is represented as a difference in weight across the front axle relative to the Left wheel. For example, if the readout shows “-100 (lbs or N) to the Left Front”, the Right- Front wheel has 100 lbs or Newtons more than the Left-Front wheel when in the garage. Higher Cross Weight values (Lower or More Negative to the left front) will induce understeer in left-hand corners and oversteer in right-hand corners. Lower Cross Weight values (Higher to the left front) will induce oversteer in left-hand corners and understeer in right-hand corners.
While this value represents only the front axle, it is important to understand that Cross Weight will also affect the weight distribution across the rear axle and can affect on-throttle traction as well. Higher Cross Weight will place more weight on the left rear tire, increasing traction on throttle out of left-hand corners and inducing on-throttle oversteer in right-hand corners. The opposite is true for lower cross-weight values, as it shifts weight onto the Right-Rear tire.

FRONT

3RD SPRING
For Road Courses a Third Spring element, in the form of a polymer bump stop, can be added to the suspension. This element works only in heave (vertical suspension travel) and can be set to prevent the car from dropping too far under heavy aerodynamic loads or vertical forces from track shape, such as dips or turn banking. Using the Third Spring in this way allows for softer corner springs to be used (since they won’t have to carry the full aerodynamic loads), increasing mechanical grip while cornering. The Third Spring is not available on Ovals.

3RD SPRING GAP
The Third Spring Gap is the distance the third spring element must compress before the third spring bump stop is engaged with higher gap values requiring more vertical travel before engagement. The Third Spring is a polymer bump stop and thus increases in rate as it is compressed, with low compression values having low spring rate and high compression values having a very high spring rate. This can be used to fine-tune the suspension’s behavior over bumps in the track surface at high speeds and high aerodynamic loads to help reduce changes in wheel load in these situations.

BAR DIAMETER
The front Anti-Roll Bar is available in three options: Large diameter, Small diameter, and None (ARB removed). The Large diameter option will stiffen the front suspension in roll, reducing mechanical grip and inducing understeer, but will try to keep the chassis flatter when cornering. The Small diameter option will reduce roll stiffness, increasing mechanical grip across the front axle and reducing understeer, but will allow the chassis to roll more. Removing the ARB will dramatically reduce roll stiffness but can provide a large increase in front end mechanical grip and increase oversteer. If the ARB is removed, all other front ARB settings do not affect the chassis.

BAR BLADES
The front ARB bar blades can be made of either Steel or Titanium (Ti) to alter the stiffness of the ARB assembly. The Steel blades are stiffer, slightly increasing roll stiffness can induce understeer. The Titanium blades are softer and will slightly reduce roll stiffness, which can reduce understeer. This adjustment has no other effect on the chassis, such as one option being lighter than the other.

BAR BLADE POSITION
The ARB blade orientation can be changed to one of six options to alter the stiffness of the ARB assembly. Represented numerically from softest (1) to stiffest (6), higher values result in a stiffer ARB while lower values soften the ARB. Stiffer settings will induce understeer while softer settings will reduce understeer. This adjustment is available as an in-car adjustment in the F8 Black Box as “ARB F”.

DROP-LINK POSITION
The ARB drop-links can be mounted in one of two positions that will alter the ARB stiffness. The “Wide (Slow)” option will reduce how fast the ARB is loaded, reducing the effective stiffness of the ARB assembly and reducing understeer. Changing to the “Narrow (Fast)” option will speed up the ARB, increasing effective stiffness and increasing understeer.

ARB PRELOAD
Adjustments to the chassis will often result in small static loads being applied to the ARB assemblies. The ARB Preload setting can be used to remove these loads to prevent any asymmetric behavior from the ARB. On Ovals it can be used to apply a static load to the bar and manage crossweight changes in banking transitions.

FRONT CORNERS

CORNER WEIGHT
Corner Weight represents the weight on each wheel when sitting in the garage. This can be used to visualize the weight distribution under static conditions and help with identifying changes to weight distribution through the setup process.

RIDE HEIGHT
Front Ride Height is a measurement from the ground to a reference point on the chassis projected to the center of the front axle. Since this value doesn’t necessarily represent the lowest point on the chassis it does not specifically represent the chassis’ ground clearance, but is instead a reference for setup and aero work. It is important to have the ride height low for both aero and mechanical grip, but high enough that the chassis doesn’t make significant contact with the race track over the course of a lap. Raising and lowering the front ride height will affect aerodynamic balance, overall downforce levels, and drag, so consult the Aero Calculator to see how a ride height change will influence handling when changing this value.

PUSHROD LENGTH
To adjust the Ride Height, shims can be added to or removed from the front suspension push rods to change their length. This is a very fine adjustment, however, close attention should be paid to Corner Weights and Cross Weight, especially when making asymmetric adjustments, to ensure weight distribution isn’t altered while changing the Pushrod Length.

SPRING RATE
Spring Rate is the stiffness of the suspension’s corner springs controlling each wheel. The value is a representation of how much force (Pounds or Newtons) is required to compress the spring a specific distance. Springs are used to keep the chassis from contacting the track under the loads seen on track and to manage the chassis’ aerodynamic attitude, but their stiffness also has a major influence on the car’s handling characteristics. On the front end, stiffer springs can keep the front wing from moving too much under increasing aerodynamic loads but will decrease mechanical grip and can cause understeer in slower corners. Softer springs will result in more front-end movement, which can hurt aero, but will increase mechanical grip in the front axle and reduce understeer (or cause oversteer, in extreme cases).

CAMBER
Camber is the vertical angle of the wheel relative to the center of the chassis. Negative camber is when the top of the wheel is closer to the chassis centerline than the bottom of the wheel, positive camber is when the top of the tire is farther out than the bottom. Higher negative camber values will provide more cornering forces in the direction of the tire’s camber (more aggressive turn-in response), but may reduce braking capability at high camber angles.
Since the Dallara IR18 runs on both ovals and road courses, the desired camber settings will change between track types. For road courses, it is best to have all four wheels set to negative camber values. For Ovals, the right-side tires should be set to negative camber values while the left-side tires should be set to positive values. The difference in camber values on ovals will often change from track to track due to varying levels of load seen on each tire. Generally, if a tire sees less load it will not be able to work with as much camber as a more heavily-loaded tire.

CASTER
Caster is the angle between the vertical and a line is drawn through the upper and lower ball joints on the front suspension, essentially representing the steering axis of the front suspension. Positive caster indicates the upper ball joint is farther back than the lower ball joint, while negative caster would indicate the upper ball joint is ahead of the lower ball joint but this is not allowed on the IR18. Caster can have many effects that must be considered during the setup process.
Increasing the caster will increase the pneumatic trail effect in the tire, which will impart directional stability and create a steering feel that seems “heavier” to the driver, with the steering wanting to straighten itself as steering input is released. It will also introduce suspension jacking forces as the angle is increased, causing more load to be shifted to the inside front wheel when the steering is turned. This decreases crossweight on turn-in and mechanically helps to turn the car in but this also increases how much the chassis rolls to the outside when steering is applied. This effect can be very helpful in slow corners, however in high-speed corners the aero effect caused by the chassis roll can be detrimental. Decreasing the caster will have the opposite effect for all conditions created by increasing the caster value. For Ovals it will often be desirable to run asymmetric caster values, with the left-front wheel running a lower amount of positive caster than the right- front wheel. This results in a natural tendency for the chassis to steer to the left as well as decreasing crossweight on turn-in, which can be very beneficial for ovals. However, as the caster increases there is a small increase in rolling drag on the tire, which can be detrimental for large ovals where top speed is crucial.

TOE-IN
Toe is the angle of the wheels relative to the chassis centerline when viewed from above. Negative toe-in sets the front of the tires farther from the centerline than the rear of the tires while positive toe-in sets the front of the tires closer to the centerline than the rear of the tires. This setting can change the front tire slip angle in a turn, with toe-out providing better turn-in response but less straight-line stability and increased tire temperature and wear. Lower toe values can provide a quicker steering response, but may produce an unstable steering feeling. Due to highly asymmetric loading on ovals, it’s not uncommon to have wildly different front Toe values on each front wheel to manage slip angle under loads. Generally, the right-front wheel will be able to utilize more toe-out than the left-front since it will see a much higher load in the corners.

REAR CORNERS

CORNER WEIGHT
Corner Weight represents the weight on each wheel when sitting in the garage. This can be used to visualize the weight distribution under static conditions and help with identifying changes to weight distribution through the setup process.

RIDE HEIGHT
Rear Ride Height is a measurement from the ground to a reference point on the chassis centerline. For the garage, only one rear ride height is shown while telemetry output will show two rear corner heights similar to the front heights. Since this value doesn’t necessarily represent the lowest point on the chassis it does not specifically represent the chassis’ ground clearance, but is instead a reference for setup and aero work. It is important to have the ride height low for both aero and mechanical grip, but high enough that the chassis doesn’t make significant contact with the race track over the course of a lap. Raising and lowering the rear ride height will affect aerodynamic balance, overall downforce levels, and drag, so consult the Aero Calculator to see how a ride height change will influence handling when changing this value.

PUSHROD LENGTH
To adjust the Ride Height, shims can be added to or removed from the rear suspension push rods to change their length. This
is a very fine adjustment, however close attention should be paid to Corner Weights and Cross Weight, especially when making asymmetric adjustments, to ensure weight distribution isn’t altered while changing the Pushrod Length. For the rear it is especially important to pay attention to the corner weights since changes to left-to-right tilt can’t be identified due to only having one ride height value for the rear.

SPRING RATE
Spring Rate is the stiffness of the suspension’s corner springs controlling each wheel. The value is a representation of how much force (Pounds or Newtons) required to compress the spring a specific distance. Springs are used to keep the chassis from contacting the track under the loads seen on track and to manage the chassis’ aerodynamic attitude, but their stiffness also has a major influence on the car’s handling characteristics. On the rear end, stiffer springs can keep the rear of the car from moving too much under increasing aerodynamic loads but will decrease mechanical grip and can cause oversteer in slower corners. Softer springs will result in more rear end movement, which can hurt aero, but will increase mechanical grip across the rear axle and reduce oversteer (or cause understeer, in extreme cases).

CAMBER
Camber is the vertical angle of the wheel relative to the center of the chassis. Negative camber is when the top of the wheel is closer to the chassis centerline than the bottom of the wheel, positive camber is when the top of the tire is farther out than the bottom. Higher negative camber values will provide more cornering forces in the direction of the tire’s camber (more stability in high-speed cornering), but may reduce on-throttle traction at high camber angles. Since the Dallara IR18 runs on both ovals and road courses, the desired camber settings will change between track types. For road courses it is best to have all four wheels set to negative camber values. For Ovals, the right-side tires should be set to negative camber values while the left-side tires should be set to positive values. The difference in camber values on ovals will often change from track to track due to varying levels of load seen on each tire. Generally, if a tire sees less load it will not be able to work with as much camber as a more heavily-loaded tire.

TOE-IN
Toe is the angle of the wheels relative to the chassis centerline when viewed from above. Negative toe-in sets the front of the tires farther from the centerline than the rear of the tires while positive toe-in sets the front of the tires closer to the centerline than the rear of the tires. This setting can change the rear tire slip angle, with toe-in providing more straight-line stability but reduce the car’s tendency to rotate into a corner. Lower toe-in values (moving towards toe-out) can provide a quicker steering response, but may produce an unstable steering feeling. Due to highly asymmetric loading on ovals, it’s not uncommon to have wildly different rear Toe values on each front wheel to manage slip angle under loads. Rear-steer can also be influenced by the rear Toe values by toeing out the right-rear wheel and toeing in the left-rear wheel. This will increase yaw in corners, which can provide aerodynamic benefits at high speed, but can induce oversteer on throttle application.

REAR

FUEL LEVEL
This shows how much fuel will be in the fuel tank when the car is loaded in the sim.

3RD SPRING
For Road Courses a Third Spring element, in the form of a polymer bump stop, can be added to the suspension. This element works only in heave (vertical suspension travel) and can be set to prevent the car from dropping too far under heavy aerodynamic loads or vertical forces from track shape, such as dips or turn banking. Using the Third Spring in this way allows for softer corner springs to be used (since they won’t have to carry the full aerodynamic loads), increasing mechanical grip while cornering. The Third Spring is not available on Ovals.

3RD SPRING GAP
The Third Spring Gap is the distance the third spring element must compress before the third spring bump stop is engaged with higher gap values requiring more vertical travel before engagement. The Third Spring is a polymer bump stop and thus increases in rate as it is compressed, with low compression values having a low spring rate and high compression values having a very high spring rate. This can be used to fine-tune the suspension’s behavior over bumps in the track surface at high speeds and high aerodynamic loads to help reduce changes in wheel load in these situations.

WEIGHT JACKER
The Weight Jacker is a device mounted to the right-rear spring that can be used to adjust the cross weight while in the car. Positive values will preload the spring and decrease the crossweight while negative values will unload the spring and increase the crossweight. The corresponding ride height changes will occur as well, with positive values raising the right rear and negative values lowering the right rear. This adjustment is not available on road courses, and must be set to zero for the car to pass tech in the garage, but is available as an in-car adjustment on the F8 Black Box as a “Weight Jacker”.

REAR ARB

ARB DIAMETER
The rear Anti-Roll Bar is available in three options: Large diameter, Small diameter, and None (ARB removed). The Large diameter option will stiffen the rear suspension in roll, reducing mechanical grip and inducing oversteer, but will try to keep the chassis flatter when cornering. The Small diameter option will reduce roll stiffness, increasing mechanical grip across the rear axle and reducing oversteer, but will allow the chassis to roll more. Removing the ARB will dramatically reduce roll stiffness but can provide a large increase in rear-end mechanical grip and increase understeer. If the rear ARB is removed and the rear springs are too soft there is a chance of lifting the inside front tire on turn-in, which can result in a wheel lockup under braking. If the ARB is removed, all other front ARB settings do not affect the chassis.

ARB DROP-LINK POSITION
The ARB drop-links can be mounted in one of two positions that will alter the ARB stiffness. The “Wide (Slow)” option will reduce how fast the ARB is loaded, reducing the effective stiffness of the ARB assembly and reducing oversteer. Changing to the “Narrow (Fast)” option will speed up the ARB, increasing effective stiffness and increasing oversteer.

ARB BL ADES
The ARB blade orientation can be changed to one of six options to alter the stiffness of the ARB assembly. Represented numerically from softest (1) to stiffest (6), higher values result in a stiffer ARB while lower values soften the ARB. Stiffer settings will induce oversteer while softer settings will reduce oversteer. This adjustment is available as an in-car adjustment in the F8 Black Box as “ARB R”.

ARB PRELOAD
Adjustment This to the chassis will often result in small static loads being applied to the ARB assemblies. The ARB Preload setting can be used to remove these loads to prevent any asymmetric behavior from the ARB. On Ovals, it can be used to apply a static load to the bar and manage crossweight changes in banking transitions.

GRAPHICS

TRANSPARENT SCREEN
Checking the Transparent Screen box will cause the Aeroscreen’s center pillar to become semi-transparent, helping with vision for those who wish to do so. This does not affect car performance.

VINYL WRAP ON WHEEL RIMS
Checking the Vinyl Wrap on Wheel Rims will enable a section of the paint template and apply it to the wheel rims. This will result in the wheels showing a color other than what was chosen for the wheels in the iRacing Paint Booth. This does not affect car performance.

VINYL WRAP ON SUSPENSION
Enabling Vinyl Wrap on the Suspension will apply a section of the paint template to the suspension arms, replacing the Carbon Fiber texture with a solid color. This does not affect car performance.

Dampers

LOW-SPEED COMP
Low-Speed Compression affects how resistant the shock is to compression (reduction in length) when the shock is moving at relatively low speeds, usually in chassis movements as a result of driver input and building aerodynamic forces. Higher values will increase compression resistance under these low-speed conditions more quickly, lower values will result in a more compliant shock. From a mechanical grip standpoint, more front low-speed compression will produce understeer under braking while more rear low-speed compression can reduce on-throttle traction to help rotation. For aerodynamics, more low-speed compression will slow vertical movement of either end of the car under braking or acceleration.

HIGH-SPEED COMP
High-Speed Compression affects the shock’s behavior in high-speed travel, usually attributed to curb strikes and bumps in the track’s surface. Higher compression values will cause the suspension to be stiffer in these situations (good for keeping the chassis from contacting the track), while lower values will allow the suspension to absorb these bumps better. Lower values will help with compliance over rough surfaces but may hurt the aerodynamic platform’s consistency around the track.

LOW-SPEED REBOUND
Low-speed Rebound damping controls the stiffness of the shock while extending at lower speeds, typically during body movement and changing aerodynamic loads. Higher rebound values will resist expansion of the shock, lower values will allow the shock to extend faster. Higher rebound values can better control aerodynamic attitude but can result in the wheels being unloaded when the suspension can’t expand enough to maintain proper contact with the track. When tuning for handling, higher front low-speed rebound can increase on- throttle mechanical understeer while lower values will maintain front-end grip longer, helping to reduce understeer. The rear is the opposite, with more low- speed rebound reducing rear grip under braking and less low-speed rebound will maintain rear grip better while the chassis is pitching forward. Lower rebound settings are usually better for tire wear but can be a detriment to aerodynamic consistency. Higher rebound can maintain a better aerodynamic platform but can lead to unwanted oscillations due to the wheel bouncing off of the track surface when the suspension can’t extend fast enough.

HIGH-SPEED REBOUND
High-speed rebound adjusts the shock in extension over bumps and kerb strikes. Higher values will reduce how quickly the shock will expand, while lower values will allow the shock to extend more easily. This value should be set low enough that the wheels can return after a bump or kerb strike but not high enough that the tire becomes unloaded when the suspension can’t expand.

Drivetrain

ENGINE

ENGINE MAP SETTING
The Engine Map Setting can be used to alter the amount of fuel sent to the engine for fuel-saving purposes.

• Setting 1 – This setting provides maximum power but the highest fuel consumption.
• Settings 2-5 – These settings are used for saving fuel. Engine power is reduced as the setting value increases, but the amount of fuel used is also reduced.
• Setting 6 – This setting is a full-power setting but with a more linear throttle map than settings 1-5 and setting 7.
• Settings 7 – This will also provide full power, but with a more digressive throttle map than settings 1 and 6.
• Setting 8 – Meant for cautions and pace laps, Setting 8 will dramatically reduce fuel flow and power.

TURBO BOOST PRESSURE
For the Indianapolis Motor Speedway oval the engine turbo can be set to a different mapping that will produce more power. This engine mode will generate more heat and use more fuel and isn’t recommended for Race sessions.

GEARBOX

FIRST – SIXTH GEAR
All six gears in the transmission can be changed to suit track conditions or driver preferences. Each gear is represented by the ratio of teeth on the input and output gears, with lower ratios reducing acceleration but increasing top speed and higher ratios increasing acceleration but reducing top speed. Once a gear is chosen and the “Apply” button is pressed, the expected top speed the gear is capable of is updated beside the ratio choice.

FINAL DRIVE
The gear ratio on the differential is represented by the Final Drive ratio. This gear ratio alters the entire acceleration and speed profile of the car without changing the individual gears in the transmission. As with the transmission gears, higher ratios will increase acceleration but reduce top speed, while lower ratios will allow for a higher top speed but reduce acceleration. Changing the Final Drive gear and clicking “Apply” will update the maximum speed for all six transmission gears.

DIFFERENTIAL (RC ONLY)
The rear differential for the IR18 can be adjusted through multiple settings, all of which can greatly affect the car’s stability, on-throttle performance, and handling characteristics. These adjustments are only available at Road Course and Street Circuits, with the car running a non-adjustable Spool rear- end at Ovals.

DIFFERENTIAL (RC ONLY)

The rear differential for the IR18 can be adjusted through multiple settings, all of which can greatly affect the car’s stability, on-throttle performance, and handling characteristics. These adjustments are only available at Road Course and Street Circuits, with the car running a non-adjustable Spool rear- end at Ovals.

CLUTCH PLATES
The differential Clutch Plates are a way to greatly increase the forces from the differential that attempt to keep the two rear axles locked in sync. The number of clutch plates used will multiply the locking force by the number of plates in use when compared to a single set of clutch plates. For example, 4 clutch plates will have 4 times the locking force of one plate, 12 will have 12 times, etc. Higher locking forces (more plates) will increase the amount of understeer seen when off the throttle under deceleration for corner entry but will increase oversteer on exit when applying the throttle. Fewer plates will increase oversteer on corner entry while decelerating but add understeer when applying the throttle.

PRELOAD
Differential Preload is a static amount of locking force that is always present in the differential regardless of acceleration or deceleration. Increasing the preload will add understeer under braking but oversteer on throttle application, while decreasing preload will add oversteer under braking but understeer on throttle application.

RAMP ANGLES
The Ramp Angles are a way to tune the differential locking on deceleration and acceleration with various configurations. The Ramp Angle values are split between “coast”, or deceleration, and “power”, or acceleration. Lower angle values will have more locking force for the situation that it is associated with, while higher angle values will have less locking force. For the “coast” adjustment, more locking force (lower ramp angles) will increase understeer while less locking force (higher angles) will increase oversteer. On the “power” side, more locking force will add oversteer on throttle and less locking force will increase understeer. Since these adjustments are somewhat independent of one another and can be chosen independently, this is a great way to fine-tune corner entry and exit once the whole corner has been tuned with the Preload and Plate number.

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