iRacing AUDI R8 LMS GT3 Racing Car User Manual
- June 4, 2024
- iRacing
Table of Contents
AUDI R8 LMS GT3
USER MANUAL
AUDI R8 LMS GT3 Racing Car
DEAR iRACING USER,
Congratulations on your purchase of the Audi R8 LMS GT3! 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!
The Audi R8 LMS GT3 ranks among the most successful GT3 cars with more than
200 international wins in events such as the Bathurst 12 Hours and Nürburgring
24 Hours, along with back-to-back championships in the 2014 and 2015 Blancpain
Endurance and Blancpain GT Series. In contrast to its all-wheel drive road-
going version, the R8 LMS GT3 is built by Audi Sport and Quattro GmbH to
comply with the rear-wheel drive-only GT3 regulations. However, the superb
balance and impressive power-to-weight ratio of the R8 LMS GT3 have made it a
winner in virtually every series in which it’s competed.
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!
INDEPENDENT DOUBLE WISHBONE SUSPENSION FRONT AND REAR
LENGTH
4583mm
180.43in| WIDTH
1997mm
78.62in| WHEELBASE
2700mm
106.30in| DRY WEIGHT
1285kg
2833lbs| WET WEIGHT
WITH DRIVER
1411kg
3111lbs
---|---|---|---|---
NATURALLY ASPIRATED V10
DISPLACEMENT
5.2Liters
317.3CID| RPM LIMIT
8500RPM| TORQUE
400lb-ft
545Nm| POWER
500bhp
374kW
---|---|---|---
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 a number of 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
Before starting the car, it is recommended to map controls for Brake Bias,
Traction Control, and ABS adjustments. While this is not mandatory to drive
the car, this will allow you to make quick changes to the driver aid systems
to suit your driving style while out on the track.
Once you load into the car, getting started is as easy as selecting the
“upshift” button to put it into gear, and hitting the accelerator pedal. This
car uses a sequential transmission and does not require a clutch input to
shift in either direction. However, the car’s downshift protection will not
allow you to downshift if it feels you are traveling too fast for the gear
selected and would incur engine damage. If that is the case, the gear change
command will simply be ignored.
Upshifting is recommended when the shift lights on the dashboard are fully
illuminated. This is at 8000 rpm.
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.
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 dash display in this car is non-adjustable and features a single page to display critical vehicle information.
DASH CONFIGURATION
FIRST ROW
TC| Current traction control setting (Illuminates yellow when in position 12
‘OFF’)
---|---
MAP| Current throttle map setting
GEAR| Currently selected gear
ABS| Current ABS setting (illuminate yellow when in position 12 ‘OFF’)
SECOND ROW
SPEED | Road speed (km/h or mph) |
---|---|
RPM | Engine RPM |
THIRD ROW
LAP | Laps completed in current outing |
---|---|
DELTA | The difference in best lap time |
FOURTH ROW
T-GEAR | Gearbox oil temperature (°C or °F) |
---|---|
T-OIL | Engine oil temperature (°C or °F) |
T-MOT | Engine water temperature (Celsius or Fahrenheit) |
FUEL LAP | Fuel used this lap (Litres or US Gallons) |
FUEL TOTAL | Fuel used during this stint (relative to a full tank) (Litres or |
US Gallons)
PIT LIMITER
When the pit limiter is active the first 5 shift light LEDs will illuminate in blue.
SHIFT LIGHTS
1 GREEN | 6650rpm |
---|---|
2 GREEN | 6800rpm |
3 GREEN | 6950rpm |
4 GREEN | 7100rpm |
1 YELLOW | 7250rpm |
2 YELLOW | 7400rpm |
1 RED | 7550rpm |
2 RED | 7700rpm |
3 RED | 7850rpm |
4 RED | 8000rpm |
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 in an incremental fashion and only singular variables are adjusted before testing changes.
Tires & Aero
TIRE SETTINGS (ALL FOUR)
COLD AIR 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 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.
HOT AIR PRESSURE
Air pressure in the tire after the car has returned to the pits. The
difference between cold and hot pressures can be used to identify how the car
is progressing through a run in terms of balance, with heavier-loaded tires
seeing a larger difference between cold and hot pressures. Ideally, tires that
are worked in a similar way should build pressure at the same rate to prevent
a change in handling balance over the life of the tire, so cold pressures
should be adjusted to ensure that similar tires are at similar pressures once
up to operating temperature. Hot pressures should be analyzed once the tires
have stabilized after a period of laps. As the number of laps per run will
vary depending upon track length a good starting point is approximately 50% of
a full fuel run.
TIRE TEMPERATURES
Tire carcass temperatures are measured via a Pyrometer, once the car has
returned to the pits. Wheel Loads and the amount of work a tire is doing on-
track are reflected in the tire’s temperature, and these values can be used to
analyze the car’s handling balance.
Center temperatures are useful for directly comparing the work done by each
tire, while the Inner and Outer temperatures are useful for analyzing the
wheel alignment (predominantly camber) while on track. These values are
measured in three zones across the tread of the tire. Inside, Middle and
Outer.
TREAD REMAINING
The amount of tread remaining on the tire once the car has returned to the
pits. Tire wear is very helpful in identifying any possible issues with
alignment, such as one side of the tire wearing excessively, and can be used
in conjunction with tire temperatures to analyze the car’s handling balance.
These values are measured in the same zones as those of temperature.
AERO CALCULATOR
The Aero Calculator is a tool provided to aid in understanding the shift in an
aerodynamic balance associated with adjustment of the rear wing setting and
front and rear ride heights. It is important to note that the values for front
and rear ride height displayed here DO NOT result in any mechanical changes to
the car itself, however, changes to the rear wing angle here WILL be applied
to the car. This calculator is a reference tool ONLY.
FRONT RH AT SPEED
The Ride Height (RH) at Speed is used to give the Aero Calculator heights to
reference for aerodynamic calculations. When using the aero calculator,
determine the car’s Front Ride height via telemetry at any point on track and
input that value into the “Front RH at Speed” setting. It is advisable to use
an average value of the LF and RF ride heights as this will provide a more
accurate representation of the current aero platform rather than using a
single corner height.
REAR RH AT SPEED
The Ride Height (RH) at Speed is used to give the Aero Calculator heights to
reference for aerodynamic calculations. When using the aero calculator,
determine the car’s Rear Ride height via telemetry at any point on track and
input that value into the “Front RH at Speed” setting. It is advisable to use
an average value of the LR and RR ride heights as this will provide a more
accurate representation of the current aero platform rather than using a
single corner height.
WING SETTING
The wing set refers to the relative angle of attack of the rear wing, this is
a powerful aerodynamic device that has a significant impact upon the total
downforce (and drag!) produced by the car as well as shifting the aerodynamic
balance of the car rearwards with increasing angle. Increasing the rear wing
angle results in more total cornering grip capability in medium to high-speed
corners but will also result in a reduction of straight-line speed. The rear
wing angle should be adjusted in conjunction with the front and rear ride
heights, specifically the difference between front and rear ride heights known
as ‘rake’. To retain the same overall aerodynamic balance it is necessary to
increase the rake of the car when increasing the rear wing angle.
FRONT DOWNFORCE
This value displays the proportion of downforce acting at the front axle for
the given wing and rides height combination set within the calculator
parameters. This value is an instantaneous representation of your aero balance
at this exact set of parameters and it can be helpful to pick multiple points
around a corner or section of track to understand how the aerodynamic balance
is moving in different situations such as braking, steady state cornering and
accelerating at corner exit. A higher forwards percentage will result in more
oversteer in mid to high-speed corners.
Chassis
FRONT
ARB BLADES
The configuration of the Anti-Roll Bar arms, or “blades”, can be changed to
alter the overall stiffness of the ARB assembly. Higher values transfer more
force through the arms to the ARB itself, increasing roll stiffness in the
front suspension and producing the same effects, albeit on a smaller scale, as
increasing the diameter of the sway bar. Conversely, lower values reduce the
roll stiffness of the front suspension and produce the same effects as
decreasing the diameter of the sway bar. These blade adjustments can be
thought of as fine-tuning adjustments between sway bar diameter settings. 6
ARB blade options are available ranging from 1-1 (softest) to 3-3 (stiffest).
ARB OUTER DIAMETER
The ARB (Anti-Roll Bar) size influences the stiffness of the front suspension
in roll, such as when navigating a corner. Increasing the ARB size will
increase the roll stiffness of the front suspension, resulting in less body
roll but increasing mechanical understeer.
This can also, in some cases, lead to more responsive steering feel from the
driver. Conversely, reducing the ARB size will soften the suspension in roll,
increasing body roll but decreasing mechanical understeer. This can result in
a less-responsive feel from the steering, but grip across the front axle will
increase. Along with this, the effects of softening or stiffening the ARB in
relation to aerodynamics should also be considered, smaller and hence softer
ARBs will result in more body roll which will decrease control of the aero
platform in high-speed corners and potentially lead to a loss in aero
efficiency. 4 configurations of ARB diameter are available and range from
disconnected (softest) to large (stiffest).
TOE-IN
Toe is the angle of the wheel, when viewed from above, relative to the
centerline of the chassis. Toe-in is when the front of the wheel is closer to
the centerline than the rear of the wheel, and Toe-out is the opposite. On the
front end, adding toe-out will increase slip in the inside tire while adding
toe-in will reduce the slip. This can be used to increase straight-line
stability and turn-in responsiveness with toe-out. Toe-in at the front will
reduce turn-in responsiveness but will reduce temperature buildup in the front
tires.
FRONT MASTER CYLINDER
The Front Brake Master Cylinder size can be changed to alter the line pressure
to the front brake calipers. A larger master cylinder will reduce the line
pressure to the front brakes, this will shift the brake bias rearwards and
increase the pedal effort required to lock the front wheels. A smaller master
cylinder will do the opposite and increase brake line pressure to the front
brakes, shifting brake bias forward and reducing required pedal effort. 7
Different master cylinder options are available ranging from 15.9 mm / 0.626”
(highest line pressure) to 23.8 mm / 0.937” (lowest line pressure).
REAR MASTER CYLINDER
The Rear Brake Master Cylinder size can be changed to alter the line pressure
to the rear brake calipers. A larger master cylinder will reduce the line
pressure to the rear brakes, this will shift the brake bias forwards and
increase the pedal effort required to lock the rear wheels. A smaller master
cylinder will do the opposite and increase brake line pressure to the rear
brakes, shifting brake bias rearward and reducing required pedal effort. 7
Different master cylinder options are available ranging from 15.9 mm / 0.626”
(highest line pressure) to 23.8 mm / 0.937” (lowest line pressure).
BRAKE PADS
The vehicle’s braking performance can be altered via the Brake Pad Compound.
The “Low” setting provides the least friction, reducing the effectiveness of
the brakes, while “Medium” and “High” provide more friction and increase the
effectiveness of the brakes while increasing the risk of a brake lockup.
GROSS WEIGHT
The percentage of total vehicle weight in the garage acting across the right
front and left rear corners. 50.0% is generally optimal for non-oval tracks as
this will produce symmetrical handling in both left and right-hand corners
providing all other chassis settings are symmetrical. Higher than 50% cross
weight will result in more understeer in left-hand corners and increased
oversteer in right-hand corners, cross weight can be adjusted by making
changes to the spring perch offsets at each corner of the car.
IN-CAR DIALS
BRAKE PRESSURE BIAS
Brake Bias is the percentage of braking force that is being sent to the front
brakes. Values above 50% result in greater pressure in the front brake line
relative to the rear brake line which will shift the brake balance forwards
increasing the tendency to lock up the front tires but potentially increasing
overall stability in braking zones. This should be tuned for both driver
preference and track conditions to get the optimum braking performance for a
given situation. It is important to note that differing combinations of master
cylinder size will necessitate differing brake pressure bias values, this is
because increasing or reducing the split in the master cylinder size
difference between front and rear axles will produce an inherent forward or
rearward bias in brake line pressure.
TRACTION CONTROL SETTING
The position of the traction control switch determines how aggressively the
ECU cuts engine torque in reaction to rear wheel spin.
12 positions are available but only 10 maps exist. Settings 1-10 range from
least intervention/sensitivity (position 1) through to highest
intervention/sensitivity (position 10). Position 11 is the same as position 10
and position 12 disables the traction control completely. Positions 3 and 4
are the manufacturer’s recommended baseline settings. More intervention will
result in less wheelspin and less rear tire wear but can reduce overall
performance if the traction control is cutting engine torque too aggressively
and stunting corner exit acceleration.
THROTTLE SHAPE SETTING
Throttle shape setting refers to how changes in the driver’s pedal position
result in changes in provided engine torque. 3 positions exist, position 1
results in a linear torque map relative to throttle position (e.g. 10%
throttle position results in 10% engine torque, 50% throttle position results
in 50% engine torque, and so on.). Position 3 emulates a non-linear S-shaped
map similar to a cable throttle which results in reduced fidelity in the
middle portion of the throttle range. Position 2 is a hybrid of position 1 and
3 throttle mapping styles.
ABS SETTING
The current ABS map the car is running. Similar to the traction control
setting, 12 positions are available but only 10 maps exist.
Position 1 has the least intervention/support while position 10 has the most
support. Position 11 is the same as position 10 and position 12 disables the
ABS completely. Positions 4 is the manufacturer’s recommended baseline
setting. More intervention reduces the possibility of and the duration of
lockups during braking but can result in longer braking distances if the
system is set overly aggressively for the amount of available grip.
LEFT/RIGHT FRONT
CORNER WEIGHT
The weight underneath each tire under static conditions in the garage. Correct
weight arrangement around the car is crucial for optimizing a car for a given
track and condition. Individual wheel weight adjustments and cross weight
adjustments are made via the spring perch offset adjustments at each corner.
FRONT RIDE HEIGHT
Distance from ground to a reference point on the chassis. Since these values
are measured to a specific reference point on the car, these values may not
necessarily reflect the vehicle’s ground clearance, but instead, provide a
reliable value for the height of the car off of the race track at static
values. Adjusting Ride Heights is key for optimum performance, as they can
directly influence the vehicle’s aerodynamic performance as well as mechanical
grip. Increasing front ride height will decrease front downforce as well as
decrease overall downforce, but will allow for more weight transfer across the
front axle when cornering. Conversely, reducing ride height will increase
front and overall downforce, but reduce the weight transfer across the front
axle. The minimum legal front ride height is 50.0 mm.
SPRING PERCH OFFSET
Used to adjust the ride height at this corner of the car by changing the
installed position of the spring. Increasing the spring perch offset will
result in lowering this corner of the car while reducing the spring perch
offset will raise this corner of the car. These changes should be kept
symmetrical across the axle (left to right) to ensure the same corner ride
heights and no change in cross weight. The spring perch offsets can also be
used in diagonal pairs (LF to RR and RF to LR) to change the static cross
weight in the car.
SPRING SELECTED/SPRING RATE
This setting determines the installed corner spring stiffness. Stiffer springs
will result in a smaller variance in ride height between high and low load
cases and will produce superior aerodynamic performance through improved
platform control however, they will also result in increased tire load
variation which will manifest as a loss in mechanical grip. Typically the
drawbacks of stiffer springs will become more pronounced on rougher tracks and
softer springs in these situations will result in increased overall
performance. Corner spring changes will influence both roll and pitch control
of the platform and ARB changes should be considered when altering corner
spring stiffnesses in order to retain the same front to rear roll stiffness
and overall balance.
When reducing corner spring stiffness the ARB stiffness (either via blade or
diameter depending on the size of the corner spring change) should be
increased to retain the same roll stiffness as previously. 6 options for
spring rate are available ranging from 160 N/mm (914 lbs/in) to 280 N/mm (1600
lbs/in). The first portion of range from 160 N/mm (914 lbs/in) to 250 N/mm
(1429 lbs/in) is in 30 N/mm (172 lbs/in) steps for coarse adjustment while the
final 3 rates are stepped in 15 N/mm (86 lbs/in) steps for fine adjustment.
Spring perch offsets must be adjusted to return the car to the prior static
ride heights after any spring rate change.
COMPRESSION DAMPING
The compression damping setting is a paired adjustment controlling both the
low and high-speed damping characteristics of the damper. In this case, -24 is
minimum damping (least resistance to compression) while 0 is maximum damping
(most resistance to compression). Increasing the compression damping will
result in a faster transfer of weight to this corner of the car during
transient movements such as braking and direction change with increased
damping usually providing an increase in turn-in response but a reduction in
overall grip in the context of front dampers. High-speed compression damping
will increase proportionally to the increase in low-speed compression damping
which will also result in a harsher response to curb strikes. At smoother
tracks, more compression damping will typically increase performance while at
rougher tracks or ones with aggressive
curbs less compression damping can result in an increase in mechanical grip at
the expense of platform control.
REBOUND DAMPING
The Rebound damping setting is a paired adjustment to both low and high-speed
rebound damping characteristics. Increasing rebound damping will slow down the
rate at which the damper extends in both low and high-speed situations. A
typical low damper speed situation would be as the car rolls back to level on
a corner exit while a high-speed situation would be where the suspension is
extending after large curb contact. -24 is minimum damping (least resistance
to extension) while 0 is maximum damping (most resistance to extension). While
high rebound stiffness will result in improved platform control for
aerodynamic performance and overall chassis response it is important to avoid
situations where the shock is too slow in rebounding as this will result in
the tire losing complete contact with the track surface which can induce or
exacerbate severe oscillations.
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, and positive camber is when the top
of the tire is farther out than the bottom. Due to the suspension geometry and
corner loads, negative camber is desired on all four wheels. Higher negative
camber values will increase the cornering force generated by the tire but will
reduce the amount of longitudinal grip the tire will have under braking.
Excessive camber values can produce very high cornering forces but will also
significantly reduce tire life, so it is important to find a balance between
life and performance. Increasing front camber values will typically result in
increased front axle grip during mid to high-speed cornering but will result
in a loss of braking performance and necessitate a rearward shift in brake
bias to compensate.
CASTER
The caster is the vertical angle of the steering axis relative to the side
view of the chassis. A positive caster angle is where the steering axis is
leaned rearwards from this viewpoint, the more caster the larger the total
trail of the contact patch behind the steering axis. More caster angle will
result in the mechanical trail being a larger proportion of the felt steering
weight relative to the tire’s pneumatic trail. This will result in a heavier
overall steering feel but a possible loss in felt feedback from the tire.
Increasing caster angle will also have secondary effects such as an increase
in dynamic camber when turning the wheel through large steering angles which
can be beneficial in chances or hairpins. As well as this the more caster
angle the greater the jacking effect during cornering which will result in
lifting the inside front wheel while lowering the outside front wheel. This
jacking effect will also result in the unloading and potentially lifting of
the inside rear wheel which can aid in rotation around tight corners.
LEFT/RIGHT REAR
REAR RIDE HEIGHT
Distance from the ground to a reference point on the rear of the chassis.
Increasing rear ride height will decrease rear downforce as well as increase
overall downforce and will allow for more weight transfer across the rear axle
when cornering. Conversely, reducing ride height will increase the rear
downforce percentage but reduce overall downforce while reducing the weight
transfer across the rear axle. Rear ride height is a critical tuning component
for both mechanical and aerodynamic balance considerations and static rear
ride heights should be considered and matched to the chosen rear corner
springs for optimal performance.
The minimum legal rear ride height is 50.0 mm while the maximum legal rear
ride height is 90.0 mm.
SPRING SELECTED/SPRING RATE
Similar to the front axle, stiffer springs will result in a smaller variance
in ride height between high and low load cases and will produce superior
aerodynamic performance through improved platform control at the expense of
mechanical grip. This can be particularly prominent when exiting slow-speed
corners with aggressive throttle application. Stiffer springs will tend to
react poorly during these instances especially so on rough tracks which will
result in significant traction loss. Spring stiffness should be matched to the
needs of the racetrack and set such that the handling balance is consistent
between high and low-speed cornering. As an example case, a car that suffers
from high-speed understeer but low-speed oversteer could benefit from an
increase in rear spring stiffness. This will allow for a lower static rear
height which will reduce rear weight transfer during slow-speed cornering
while maintaining or even increasing the rear ride height in high-speed
cornering to shift the aerodynamic balance forwards and reduce understeer. 6
options for spring rate are available ranging from 190 N/mm (1086 lbs/in) to
310 N/mm (1771 lbs/in). The first portion of the range from 190 N/mm (1086
lbs/in) to 250 N/mm (1429 lbs/in) is in 30 N/mm (172 lbs/in) steps for coarse
adjustment while the next 2 rates are stepped in 15 N/mm (86 lbs/in) steps for
fine adjustment. Spring perch offsets must be adjusted to return the car to
the prior static ride heights after any spring rate change.
COMPRESSION DAMPING
The compression damping setting is a paired adjustment controlling both the
low and high-speed damping characteristics of the damper with identical ranges
to those of the front dampers. Increasing the compression damping will result
in a faster transfer of weight to this corner of the car during transient
movements such as accelerating and direction change with increased damping
usually providing an increase in response but a reduction in overall grip
especially at corner exit traction in the context of rear dampers. Excessively
stiff compression damping can cause very poor traction on rough tracks as it
can result in large tire load variation and a reduction in overall grip.
REBOUND DAMPING
The rebound damping setting is a paired adjustment controlling both the low
and high-speed damping characteristics of the damper with identical ranges to
those of the front dampers. Increasing rebound damping will slow down the rate
at which the damper extends in both low and high-speed situations. As at the
front, high rebound stiffness will result in improved platform control for
aerodynamic performance and overall chassis response but it is important to
avoid situations where the shock is too slow in rebounding as this will result
in the tire losing complete contact with the track surface. This can be
particularly detrimental during braking events and during the initial turn-in
phase through an increase in rebound stiffness can help to ‘slow down the
change in pitch of the car as the brakes are applied, potentially increasing
braking stability.
CAMBER
As at the front of the car it is desirable to run significant amounts of
negative camber in order to increase the lateral grip capability however, it
is typical to run a slightly reduced rear camber relative to the front. This
is primarily for two reasons, firstly, the rear tires are 25 mm (~1”) wider
compared to the fronts and secondly the rear tires must also perform the duty
of driving the car forwards where benefits of camber to lateral grip become a
tradeoff against reduced longitudinal (traction) performance.
TOE-IN
At the rear of the car, it is typical to run toe-in. Increases in toe-in will
result in improved straight-line stability and a reduction in response during
direction changes. Large values of toe-in should be avoided if possible as
this will increase rolling drag and reduce straight line speeds. When making
rear toe changes remember that the values are for each individual wheel as
opposed to paired as at the front. This means that individual values on the
rear wheels are twice as powerful as the combined adjustment at the front of
the car when the rear toes are summed together. Generally, it is advised to
keep the left and right toe values equal to prevent crabbing or asymmetric
handling behavior however, heavily asymmetric tracks such as Lime Rock Park
may see a benefit in performance from running asymmetric configurations of the
rear toe and other setup parameters.
REAR
FUEL LEVEL
The amount of fuel in the fuel tank. The tank capacity is 120 L (31.7 g).
Adjustable in 1 L (0.26 g) increments.
ARB BLADES
The configuration of the Anti-Roll Bar arms, or “blades”, can be changed to
alter the overall stiffness of the ARB assembly. Higher values transfer more
force through the arms to the ARB itself, increasing roll stiffness in the
rear suspension and producing the same effects, albeit on a smaller scale, as
increasing the diameter of the sway bar. Conversely, lower values reduce the
roll stiffness of the rear suspension and produce the same effects as
decreasing the diameter of the sway bar. These blade adjustments can be
thought of as fine-tuning adjustments between sway bar diameter settings. 6
ARB blade options are available ranging from 1-1 (softest) to 3-3 (stiffest).
ARB OUTER DIAMETER
The ARB (Anti-Roll Bar) size influences the stiffness of the rear suspension
in roll, such as when navigating a corner. Increasing the ARB size will
increase the roll stiffness of the rear suspension, resulting in less body
roll but increasing mechanical oversteer. This can also cause the car “take a
set” more quickly at initial turn-in. Conversely, reducing the ARB size will
soften the suspension in roll, increasing body roll but decreasing mechanical
oversteer. This can result in a less-responsive feel from the rear, especially
in transient movements, but grip across the rear axle will increase. 4
configurations of ARB diameter are available and range from disconnected
(softest) to large (stiffest).
SIXTH GEAR
Two options of 6th gear are available for selection depending upon track type.
The FIA gear is shorter and should be used at the majority of tracks while the
IMSA Daytona gear should be used at Daytona and Le Mans to prevent reaching
the rev limiter before the end of the straightaways.
DIFF PRELOAD
Diff preload is a static amount of locking force present within the
differential and remains constant during both acceleration and deceleration.
Increasing diff preload will increase locking on both sides of the
differential which will result in more understeer when off throttle and more
snap oversteer with aggressive throttle application. Increasing the diff
preload will also smooth the transition between on and off throttle behavior
as the differential locking force will never reach zero which can be helpful
in reducing lift-off oversteer and increasing driver confidence. Typically
diff preload should be increased when there is a noticeable loss in slow
corner exit drive and/or over-rotation during the transition between the
throttle and brake in low to mid-speed corners.
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