Basic Road Course Setup Building for Star Mazda

Link to .sto File

iRacing.com Formulamazda setup:

RFCBaseSM2016S1 v1.0

FRONT:

Cold pressure: 20.5 psi

REAR:

Cold pressure: 20.5 psi

FRONT AERO:

Wing flap angle: 24.0 deg
Wing mainplane angle: 5.5 deg
Wing flap gurney: 1/4" - 6.4mm

REAR AERO:

Wing upper element setting: A1
Wing lower element angle: 7.5 deg
Wing lower element flap gurney: None
Wing end plate vertical gurney: Full Length

AERO CALCULATOR:

Front RH at speed: 0.875"
Rear RH at speed: 1.000"
Front downforce: 54.62%
Downforce to drag: 1.810:1

FRONT:

ARB diameter: Large
ARB blades: 2
ARB preload: -0.0 ft-lbs
Toe-in: -1/16"
Brake pressure bias: 55.7%

LEFT FRONT:

Corner weight: 288 lbs
Ride height: 0.910 in
Spring perch offset: 2.500"
Spring rate: 800 lbs/in
ARB rocker hole: Fast
Camber: -2.2 deg
Caster: +8.9 deg

LEFT REAR:

Corner weight: 398 lbs
Ride height: 1.175 in
Spring perch offset: 2.469"
Spring rate: 700 lbs/in
ARB rocker hole: Slow
Camber: -1.5 deg

RIGHT FRONT:

Corner weight: 288 lbs
Ride height: 0.910 in
Spring perch offset: 2.500"
Spring rate: 800 lbs/in
ARB rocker hole: Fast
Camber: -2.2 deg
Caster: +8.9 deg

RIGHT REAR:

Corner weight: 398 lbs
Ride height: 1.175 in
Spring perch offset: 2.469"
Spring rate: 700 lbs/in
ARB rocker hole: Slow
Camber: -1.5 deg

REAR:

Fuel level: 4.0 gal
Toe-in: +1/16"
ARB preload: -0.0 ft-lbs
Cross weight: 50.0%

LEFT FRONT DAMPER:

Low speed comp: -12 clicks
High speed comp: -15 clicks
Low speed rebound: -7 clicks
High speed rebound: -14 clicks

LEFT REAR DAMPER:

Low speed comp: -7 clicks
High speed comp: -12 clicks
Low speed rebound: -5 clicks
High speed rebound: -12 clicks

RIGHT FRONT DAMPER:

Low speed comp: -12 clicks
High speed comp: -15 clicks
Low speed rebound: -7 clicks
High speed rebound: -14 clicks

RIGHT REAR DAMPER:

Low speed comp: -7 clicks
High speed comp: -12 clicks
Low speed rebound: -5 clicks
High speed rebound: -12 clicks

Gearbox:

First gear: 12/29
69.8 mph
Second gear: 15/32
79.1 mph
Third gear: 15/25
101.2 mph
Fourth gear: 19/27
118.7 mph
Fifth gear: 20/25
134.9 mph
Sixth gear: 19/21
152.6 mph

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.  

Keep in mind that the Star Mazda has an “open” differential and will handle a bit differently than cars with a spool or locking differential. It is generally driven with a bit of “trailing throttle oversteer” which allows the driver to steer the car with throttle application, to some degree.  This set introduces significant “trailing throttle oversteer” and requires some “maintenance throttle” to hold the rear when turning.

First, run the “Base”  set for 10 laps and get a baseline set of lap times. 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 and set a “target lap time”. (This is a different procedure than the typical concept of choosing downforce to improve cornering---the idea is that top speed is limited by the gearing and aero settings you choose.)

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 152.6 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 88-90% of 6^th gear; 4^th gear Max Speed Possible at 87-88% of 5^th gear; 3^rd gear Max Speed Possible at 85-87% of 4^th gear; 2^rd gear Max Speed Possible at 78-84% of 3rd gear; and 1^st gear Max Speed Possible at 88-90% of 2nd gear. (2^nd gear is the most often used gear for slow corner exits.)

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 48-55% 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. In previous seasons the front downforce % was a lower range   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.)

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 500 pounds for the rear springs.) 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.

Note: On tracks with fast sweeping corners, often a spring rate that is higher in the rear works well. On tracks with chicanes and hairpins requiring acceleration from a slow speed, a lower spring rate in the rear is usually better. On tracks with chicanes requiring fast direction change, sometimes it is beneficial to increase the front spring rate. Changing springs by a significant amount from the base requires attention to ARB settings. See Note at end.

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.  Generally, the Star Mazda should be run with low ride heights—just low enough to not hit the track. This produces "ground effects" downforce with little increase in drag.  One may choose to increase downforce (and drag) by increasing “rake”—raising the rear height.  The car will also tend to turn better in mid-corner with a higher rake.

After adjusting ride height/s, Run another 10 laps and compare lap times and handling. Note tire wear and temps. 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.

You may gain speed by reducing the rear toe to zero—you may also increase rear toe-in on slower tracks to help the rear stick better on acceleration. Increasing toe-out on the front can help the car turn in more quickly.

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.  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. 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.

Colder temps generally allow less wing. Hotter temps generally require more wing (downforce). But this is not always the case—it depends on the track.

Usually qualifying is done with 2 gallons of fuel. The race is generally run with 4-5 gallons. You may wish to lower the front ride height for qualifying.

Often, it will require 4 to 6 different setups to cover the range of temperatures for qualifying and racing.

This is by no means a complete instruction. There are other adjustments that can be made. (like front brake bias and ARB settings) 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, braking and throttle modulation are part of how best lap times are achieved. Most often, if someone is going faster, it is not because they have a better setup--rather, they are simply using a better technique and moving their hands and feet more quickly. It is not uncommon for a "great" driver to be 2 seconds a lap quicker than a "good " driver using the same exact setup.

Note: Anti Roll Bar or ARB settings essentially affect the car in a similar way as running a higher spring rate, except the ARB only makes the car stiffer when rolling and not in forward/rearward pitch.  A stiff ARB on the front provides more rear tire grip during acceleration.  A weaker front ARB will allow the car to turn in mid corner better. Be aware that stiffening the front ARB can result in the inside tire lifting when turning, causing the inside tire to lock up while trail braking.

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/