Basic Road Course Setup Building for DW12

Link to Dropbox .sto file
RFC Road Q BASE setup 2016S1

https://www.dropbox.com/s/ri7ryrqcm0bhrmm/RFC2016S1BaseRoad.sto?dl=0

iRacing.com RFC2016S1BaseRoad for IndyCar DW12
(Formatted for PC--see end of article for settings formatted for mobile devices)

FRONT:                                                                     REAR:

Cold pressure: 25.0 psi                                               Cold pressure: 23.0 psi
FRONT AERO:                                          REAR AERO:

Wing angle: 28.50 deg                                               Wing angle: 46.0 deg
Wing wicker: 1" full span                                           Wing wicker: 1/2" full span
Upper flap angle: 11.5 deg                                         End plate wicker: 3/8"
Upper flap wicker: 1/4"                                              Beam wicker: 1"
UNDERSIDE AERO:                                 AERO CALCULATOR:

Diffuser exit wicker: 3/4" (sealed)                              Front RH at speed:  0.500"
Diffuser add-ons: Sidewall ON/Strakes ON              Rear RH at speed:   0.500"
Radiator inlet: 2/3 closed EXT side                           Front downforce:    40.93%

                                                                                    Downforce to drag: 3.040:1

GENERAL:

Wheelbase: 118"                                                         Steering offset: +0 deg
Brake pressure: Medium                                             Ballast forward: -6"
Brake pressure bias: 52.0%                                        Nose weight: 44.7%
Steering pinion: 8 tooth                                   Cross weight: -0 lbs to the left front

FRONT:                                                     REAR:

Corner weight: 404 lbs (44.7% Front)                        Corner weight: 499 lbs
Ride height: 1.114 in                                                  Ride height: 1.596 in
Pushrod length: 25.545"                                             Pushrod length: 21.089"
Spring rate: 1750 lbs/in                                               Spring rate: 650 lbs/in
Camber: -2.13 deg                                                      Camber: -1.60 deg
Caster: +7.36 deg                                                        NA
Toe-in: -2/32"                                                              Toe-in: +5/32"

FRONT:                                                     REAR:

3rd spring: Stiff                                                          3rd spring: Stiff
3rd spring gap: 0.338 in                                              3rd spring gap: 0.321 in
ARB diameter: Small                                                  ARB diameter: Large
ARB blades: Steel
ARB blades: 3                                                             ARB blades: 2
ARB Drop-link position: Wide (Slow)            ARB drop-link position: Wide (Slow)
ARB preload: 0.0 ft-lbs                                              ARB preload: 0.1 ft-lbs

Fuel level: 4.5 gal                                                       Weight jacker: 0

FRONT DAMPER:                                   REAR DAMPER:

Low speed comp: -7 clicks                                      Low speed comp: -19 clicks
High speed comp: -21 clicks                                  High speed comp: -23 clicks
Low speed rebound: -7 clicks                              Low speed rebound: -23 clicks
High speed rebound: -14 clicks                           High speed rebound: -20 clicks

ENGINE:

Engine map setting: 7 (MAP) (Less sensitive)  
Turbo boost pressure: Push to Pass 10x/race

GEARBOX:        Final drive: 17/59

First gear: 16/34          109.3 mph                   Second gear: 17/31     127.4 mph
Third gear: 19/31        142.4 mph                   Fourth gear: 19/28      157.6 mph
Fifth gear: 18/25         167.3 mph                   Sixth gear: 20/26         178.7 mph
DIFFERENTIAL:

Clutch plates: 4                                                           Preload: -50 ft-lbs
Ramp angles: 45 coast/30 power

Just like for ovals, building a competitive setup for road courses requires trial and error testing.  While one could start from scratch for each track, each season, it is often time efficient to build on already existing setups.

This article shares a “Base” setup tested for iRacing’s 2016S1 “Build”.  (Sometimes iRacing makes changes to chassis stiffness and tire grip/slip angle coefficients that may require minor changes to the base in the future.)

This “Base” setup is designed for a “balanced” car—neither “tight=under-steery” or “loose=over-steery”.  For each track, this is a starting point and modifications and adjustments need to be made and tested for optimal performance.

First, run the “Base”  set for 10 laps and get a baseline set of lap times. (You will need to increase fuel level to 7 or 8 gallons temporarily.) Note the top speed. (If you hit the rev limiter in 6^th gear, then adjust it to a higher mph setting and determine the top speed before ending the first stage testing.) Also note the gears used entering and exiting each corner.

Before proceeding further—view Youtube videos of hot laps at the track run by other drivers. Note the top speed and the gears used entering and exiting each corner. Note the driving lines taken and braking points if possible. Check iRacing results and World Records (Only during the last 12 months) and set a “target lap time” for certain track temperature. 

IMPORTANT TERM:   A Balanced Race Car is one where the front and the rear tires are close to the same temperature and wear---this is the goal. With the correct driving line, you will “feel” this with the car not being “generally” loose or tight. But, on road courses, in most cases a compromise is required—some corners the car may seem loose while in others it may seem tight.

IMPORTANT TERM:  Best Camber for Racing Grip is the setting that produces almost equal tire wear from left to right of each tire. (This may not be the best setting for qualifying, but for racing it produces the setting that will provide the best lap times for long runs.) On road courses, because of necessary and desirable negative camber, generally the temperature and wear on the outside edges will be lower.

The first adjustment will be to setup the gearbox so that desired top speed is achieved in 6^th gear with Max Speed Possible (hitting the rev limiter—this is 178.7 mph in the Base Set) approximately 5-6 mph higher than the desired top speed. (This allows for the draft.) Then set 5^th gear Max Speed Possible at 93-94% of 6^th gear; 4^th gear Max Speed Possible at 92-94% of 5^th gear; 3^rd gear Max Speed Possible at 90-93% of 4^th gear; 2^rd gear Max Speed Possible at 87-90% of 3rd gear; and 1^st gear Max Speed Possible at 85-87% of 2nd gear.

Run 10 laps to verify you are reaching the desired top speed. If you are not hitting the rev limiter and not reaching the desired top speed, then you must reduce aerodynamic drag.  Reduce the front and rear wings as necessary to maintain a 40-42% Front Downforce % and a Balanced Race Car tire condition as well as the desired handling in the fastest corner and corner/s leading to the longest straight. Note the gears used entering and exiting the corners and make adjustments as necessary. (The main issue is that you usually would prefer to be upshifting after the track out point on corner exit. Make minor changes to gearing—one step only.)  (This is a different procedure than the typical concept of choosing downforce to improve cornering---the idea is that desired top speed is limited by the gearing and aero settings you choose.)

Finding the right “combination” of wing angle/s, wicker dimensions takes a bit of trial and error using the Aero Calculator as a guide.  Choose the combination giving the highest Downforce to Drag ratio. Here is where you may choose to add aero downforce to improve handling and lap times, even though it may reduce your top speed.

Once a Balanced Race Car and desired top speed is achieved by adjusting wings, run another 10 laps to establish a new baseline set of lap times. Note the presence of tight or loose conditions.

Before proceeding further, carefully consider the choice of spring rates. The “Base” setup produces certain handling characteristics that can be changed simply by changing spring rates. Increasing the front spring rates will make the car tighter. (Drivers who like to brake later may desire this.) Decreasing the front spring rates will make the car more loose. Increasing the rear spring rates will make the car more loose. (Drivers who like to “steer with throttle may desire this.) Decreasing rear spring rates will make the car tighter. (It is not recommended going much lower than 650 pounds for the rear springs that are used in the “Base” setup.) If you change springs, reset ride height back to the “Base” settings and run a few test laps to insure the car is a Balanced Race Car. Adjust aero as needed.

There is no "magic" formula for the correct tire pressure. Best advice is to experiment at each track with increasing and decreasing tire pressure from the base. Generally, tracks with fast sweeping corners call for higher pressure. And, tracks with slow chicanes and hairpins call for lower pressure.

Before making any further adjustments, using ALT L, and some form of telemetry software analysis, note the ride heights on all four corners.  If the car is hitting the track during corners, then ride height needs to be increased. Generally, at corner entry, the optimum ride front height under heavy braking would be not be much more than 0.2 inches—often you will desire it to be near zero.  On the longer straights for maximum speed, front ride height should be no lower than 0.6 inches and it is generally good for the rear ride height to be 0.3 inches higher in the rear than the front. However, one may choose to increase downforce (and drag) by increasing “rake”—raising the rear height above this 0.3 inch figure and running a front ride height on the straights that is less than 0.6 inches which will also increase downforce.

Note that on the DW12 road course setup—you have a choice of “3^rd Spring Gap”. The 3^rd spring comes into play when both sides (L and R) of the car are lowered by aero downforce, braking or acceleration. If the car is running too low at maximum speed or during braking, one can reduce this 3^rd Spring Gap—essentially causing the 3^rd spring to supplement/add to the spring rate of the conventional springs. Retest telemetry after making this change.

After adjusting ride height/s, Run another 10 laps and compare lap times and handling. Note tire wear and temps. On particularly fast tracks, you may gain speed by reducing the rear toe . This benefit will be at the expense of a car that is looser when applying power in a corner.

You will now start making adjustments to remedy the handling issues you observe without adjusting wings. You will focus on improving the handling in specific corners as well as improving tire wear/temps.

First, adjust front and rear camber to optimum. Keep in mind the principle of “Camber Thrust” where tires on the outside of the curve tend to produce more lateral grip with a small amount of negative camber but produce less on the inside of the curve. (See figure below.) Keep in mind that "A Arm" suspensions usually generate more negative camber as they are compressed.  Generally, tire temps should be about 5% cooler on the outside. Next, choose the desired Caster. Higher Caster setting will make the car more loose in mid corner. More front ARB will give more rear traction and make the car tighter. Less rear ARB will give more rear grip and make the car tighter.  Finally, choose the optimum damper settings. Generally, reducing high speed compression and rebound makes the car better able to go over curbs. Reducing low speed rebound settings will give that corner more relative grip; increasing compression settings will give that corner less grip. Keep in mind that changes to grip from damper setting are “dynamic” or momentary—they simply control/affect the speed that weight/cornering load is transferred.

The figure above gives a bit of insight about the high and low speed damper settings.The low speed settings affect the damper when moving at 1-2 inches per second. The high speed settings affect the damper when moving faster than that. The rate of damping force increase relative to speed is different for high speed movement vs. low speed. Rebound damping is higher than compression damping because the spring is acting to accelerate the damper's movement.

Continue running 5-10 laps “Stints” after each change. Be careful that you do not confuse the improvement in lap times due to your improved driving with improvement caused by adjustments you make to the car. Often it is wise to reverse the change and test to see if lap times get worse when the change is reversed. Let your lap times determine the best setup. Be aware that changes can improve performance in one corner while making performance in another corner worse.

Road course setups do not have Qualifying Boost. Instead, they provide 10 Push to Pass Boosts per race. When comparing lap times be aware of Push to Pass Boosts used. Often during Official Practice sessions, other drivers will use several Push to Pass Boosts to get an "impressive" but unrealistic lap time. Push to Pass is NOT available during Road course qualifying. Another "game" some drivers use is to report their "optimal" lap times on the forum. "I am reaching 1:xx.xx)" while their best actual lap was 1 second or more slower. 

For qualifying, generally, set fuel fuel to 4 or 4.5 gallons. (Test this and set so you have only 0.2 gallons at the end of qualifying session.) For the RACE setup, increase fuel to 18.5 gallons, and change the radiator opening to 1/3 blocked. Since the car is heavier, adjust the ride heights to compensate.  

Colder temps generally allow less wing. Hotter temps generally require more wing (downforce). You may want a higher downforce to make the car more stable as tires wear. Generally dropping tire pressure slightly will help on a hot track. Run a full fuel stint to test. These rules of thumb are not always the case—it depends on the track.

Often, it will require 6 to 8 different setups to cover the range of temperatures for qualifying and racing. Cold (70-85F track)  Medium (85-95F track) Hot (95-105 track) and ExtraHot (105F+) For 2 lap qualifying generally you only need Cold and Hot.

This is by no means a complete instruction. There are other adjustments that can be made (like front brake bias, differential settings and ballast forward) and vehicle dynamics are complicated.  Some drivers may prefer a car that is more loose than a Balanced Race Car. These “more advanced” settings should be attempted to further optimize your lap times but will require additional time consuming testing. And, remember that driving lines and throttle modulation are part of how best lap times are achieved. 

Note 1:  On courses with sharp and slow turns like Circuit of the America's, the base setup may introduce a bit of mid-corner over-steer or looseness. This is primarily caused by the rear tires being overtaxed by trail braking. A "drive-around" is to do less trail braking--brake in a straight line and release at turn in or" The "setup" fix is more front brake bias and a higher "Coast" differential setting. 

In addition to my engineering and racing background as well as 30 years of interest/study in the field of vehicle dynamics, a great deal of the knowledge and experience behind the base setup and this guide came from the excellent professional level coaching I received from nearly a year working with Wyatt Gooden. He continues to evaluate setups I build for Team RFC and almost always betters iRacing World Record laps times when doing so.    http://www.wyattgooden.com/

Here are the setting in a format better suited to mobile devices.

RIGHT FRONT: LEFT FRONT:

Cold pressure: 25.0 psi

RIGHT REAR: LEFT REAR:

Cold pressure: 23.0 psi

FRONT AERO:

Wing angle: 28.50 deg
Wing wicker: 1" full span
Upper flap angle: 11.5 deg
Upper flap wicker: 1/4"

UNDERSIDE AERO:

Diffuser exit wicker: 3/4" (sealed)
Diffuser add-ons: Sidewall ON/Strakes ON

Radiator inlet: 2/3 closed EXT side

REAR AERO:

Wing angle: 46.0 deg
Wing wicker: 1/2" full span
End plate wicker: 3/8"
Beam wicker: 1"

AERO CALCULATOR:

Front RH at speed: 0.500"
Rear RH at speed: 0.500"
Front downforce: 40.93%
Downforce to drag: 3.040:1

GENERAL:

Wheelbase: 118"
Brake pressure: Medium
Brake pressure bias: 52.0%
Steering pinion: 8 tooth
Steering offset: +0 deg
Ballast forward: -6"
Nose weight: 44.7%
Cross weight: -0 lbs to the left front

LEFT & RIGHT FRONT:

Corner weight: 404 lbs
Ride height: 1.114 in
Pushrod length: 25.545"
Spring rate: 1750 lbs/in
Camber: -2.13 deg
Caster: +7.36 deg
Toe-in: -2/32"

LEFT & RIGHT REAR:

Corner weight: 499 lbs
Ride height: 1.596 in
Pushrod length: 21.089"
Spring rate: 650 lbs/in
Camber: -1.60 deg
Toe-in: +5/32"

FRONT:

3rd spring: Stiff
3rd spring gap: 0.338 in
Bar diameter: Small
Bar blades: Steel
Bar blade position: 3
Drop-link position: Wide (Slow)
ARB preload: 0.0 ft-lbs

REAR:

Fuel level: 4.5 gal
3rd spring: Stiff
3rd spring gap: 0.321 in
Weight jacker: 0

REAR ARB:

ARB diameter: Large
ARB drop-link position: Wide (Slow)
ARB blades: 2
ARB preload: 0.1 ft-lbs

LEFT/RIGHT FRONT DAMPER:

Low speed comp: -7 clicks
High speed comp: -21 clicks
Low speed rebound: -7 clicks
High speed rebound: -14 clicks

LEFT/RIGHT REAR DAMPER:

Low speed comp: -19 clicks
High speed comp: -23 clicks
Low speed rebound: -23 clicks
High speed rebound: -20 clicks

ENGINE:

Engine map setting: 7 (MAP)
Turbo boost pressure:  Push to Pass limited to 10 times per race.

GEARBOX:

First gear: 16/34
109.3 mph
Second gear: 17/31
127.4 mph
Third gear: 19/31
142.4 mph
Fourth gear: 19/28
157.6 mph
Fifth gear: 18/25
167.3 mph
Sixth gear: 20/26
178.7 mph
Final drive: 17/59

DIFFERENTIAL (RC only):

Clutch plates: 4
Preload: -50 ft-lbs
Ramp angles: 45 coast/30 power