Forza 7 Tuning Guide

Part 2 - General Tuning

This section explains how to setup cars in a way that they will work good on all tracks.

 

This also serves a basis for track specific tuning which will be covered in part 3, so make sure to read this first before advancing to track specific tuning.

Tires

Tire pressure tuning in Forza is relatively easy as it only depends on the used tire compound.  The general rule here is the softer the tire compound the higher tire pressure is required. Reasoning for that is that besides grip tires also provide a basic level of rigidity and therefore control. Softer tire compounds like Sport or Race compound provide more grip but also have less rigidity than Stock or Street compound. Increased tire pressure compensates for lower level of rigidity of softer compounds.

Tire Compound          Tire Pressure

Stock                                     28.0

Street                                    28.0

Sport                                     28.5

Race                                      29.0

Drag                                      29.5

If you are running on stock tire compound keep in my mind that the series tire compound may not be Stock compound for all cars. For most race cars the series tire compound is Race compound (only Drag compound is available as upgrade), likewise for some sports cars the series tire compound is Sport compound (only Race and Drag compound available as upgrade). Set the tire pressures accordingly.

Note: This method will provide peak tire performance starting 3rd lap, the first two laps are needed to warm-up the tires.

Alignment

Camber

Camber settings are car type specific. As a general rule of thumb: older cars require less static camber because the more flexible chassis / suspension creates more dynamic camber. Modern cars with more rigid chassis / suspension can be run with higher camber. However due to very high forces during cornering for GP race and prototype race cars its the other way around: older gp and prototype race cars require higher camber than modern GP and prototype race cars.

Static camber should be set so that the (dynamic) camber on the apex when you start accelerating out of a turn is around 0 to maximize tire contact patch which in turn provides maximum tire grip. This is especially important for the driven wheels. 

Front camber is usually higher than rear. Exception are open-wheel cars with its very unique suspension geometry that requires higher rear camber.

Also generally AWD and FWD cars require more camber than RWD cars to combat inherent understeer. AWD cars require more rear camber than RWD cars, this is usually in the range of -0.2-0.4 as compared to RWD rear camber. FWD cars require more front camber than RWD cars, this is usually around -0.2 as compared to RWD front camber.

Car Type                               Usual Camber Range

Production Car                            -3.0 to  0.0

High Performance Car               -2.5 to -1.0

Race Car                                       -2.5 to -1.5

Prototype Race Car                     -2.5 to -0.5

Open Wheel Race Car                -3.0 to -0.5

Open Wheel Car                          -4.0 to -2.0

The ranges given account for different body types within the car type.

​Keep in my mind that tire width directly influence camber settings. This is due to wider tires increase contact patch, so for optimal grip camber needs to be reduced as well.

Car Property              Change             Effect on Camber

Front Tire Width         Increase           Reduce front camber

Front Tire Width         Decrease         Increase front camber

Rear Tire Width          Increase            Reduce rear camber

Rear Tire Width          Decrease          Increase rear camber

Toe

I usually don't touch toe as this from my experience creates almost always unwanted imbalance during turning.

The only exception is that I use rear toe-in (max. -0.3) for older production cars as I find this improves accelerating out of turns, i.e. reduces on-throttle understeer.

Car Type                                    Rear Toe

Production Car                           -0.3-0.0

High Performance Car                  0.0

Race Car                                          0.0

Prototype Race Car                       0.0 

Open Wheel Car                            0.0 

Open Wheel Race Car                  0.0

The ranges given account for different body types within the car type.

Caster

Caster is also a car type specific setting. As a general rule of thumb older cars require higher caster than modern cars and race cars require lower caster than production cars. However due to high forces during cornering GP race cars and prototype races cars generally need high caster that provides extra stability during cornering.

Each car has a "natural" caster that suits the cars suspension geometry best. You wont unlock the full potential of a car when the caster is not set to the cars natural caster.

Car Type                                    Caster

Production Car                          5.0-7.0

High Performance Car                 5.0 

Race Car                                     4.0-5.0

Prototype Race Car                   5.0-6.0

Open Wheel Car                           6.0

Open Wheel Race Car                  7.0

The ranges given account for different body types within the car type.

Higher caster creates turn-in resistance (off-throttle understeer) while lower caster reduces turn-in resistance (off-throttle oversteer). 

Older cars benefit from more turn-in resistance (i.e. high caster) whereas race cars are held back with too much turn-in resistance. 

Note: Caster should be set in 1.0 increments only, fraction numbers are not required.

Anti-roll Bars

Anti-roll bars (ARBs) control the weight transition between left and right (or inner and outer) wheels during cornering. Softer ARBs create more body roll leading to more weight shifting to the outer wheels. Stiffer ARBs reduce body roll and thus provide less weight shifting during cornering. Soft ARBs provide more grip during cornering but can result into sluggish car behaviour when setup too soft. Stiff ARBs provide more control during cornering but can result into harsh and unpredictable car behaviour when setup too stiff. 

Generally ARBs need to be setup in relation to chassis stiffness and vehicle weight, i.e. the more rigid the chassis is the lower the ARBs can be set. Likewise the less the car weights the lower the ARBs can be set.

20/20 is good middle ground for modern production cars around 3000lbs and 50% weight distribution and corresponds to an ARB stiffness of around 63%. Increase ARBs for cars with more weight and / or less rigid chassis (e.g. older cars). Decrease ARBs for cars with less weight and / or more rigid chassis (e.g. race cars).

Front and rear ARB distribution has a relation to weight distribution, so in general a car with more front weight should have also higher front ARBs than rear. This is however not as simple as 1:1 distribution according to weight distribution because springs and dampers also affect car balance during turning. 

A good starting point for ARB distribution for RWD cars is 1 per 1% weight distribution difference to 50%, i.e. for 51% front weight distribution the front ARB should be 1 higher than the rear ARB. Older cars and muscle cars require higher spread (>1 per 1%) while race cars require lower spread. 

Example: ARBs for a modern RWD production car with 3000lbs @ 51% wd would be:

ARB distribution = 51%-50% = 1% --> 1*1 = 1, divide by 2 to split equally between front and rear --> 0.5

Front: 20 + 0.5 = 20.5 and Rear: 20 - 0.5 = 19.5.

The same applies to AWD but they generally require a lower spread than RWD cars to combat inherent understeer. A good starting point is 0.66 -per 1% weight distribution for AWD cars, i.e. for 51% front weight distribution the front ARB should be 0.66 higher than rear ARB.  

For FWD cars generally ARBs need to be setup in reverse to RWD with regard to ARB distribution. So a good starting point would be -1 per 1% weight distribution for modern production cars around 3000lbs. 

Example: ARBs for a modern FWD production car with 3000lbs @ 60% wd would be:

ARB distribution = 60%-50% = 10% --> 10*-1 = -10, divide by 2 to split equally between front and rear --> -5

Front: 20 + (-5) = 15 and Rear: 20 - (-5) = 25

Car Type                         ARB stiffness         ARB distribution

Production Car                    61-65%                      0.66-1.50

High Performance Car       40-46%                      0.55-0.65

Race Car                               15-62%                      0.35-0.80

Prototype Race Car             80-82%                      0.25-0.35

GP Race Car                          84-88%                    -0.85-3.15

Open Wheel Car                  60-80%                    -3.10-1.05

The ranges given account for different body types within the car type.

Keep in my mind that adding chassis reinforcement upgrade increases chassis rigidity (sport chassis increases chassis rigidity by 3%, race chassis increases chassis rigidity by 6%), i.e. ARBs should be reduced accordingly.

Car Property                       Change                  Effect on ARBs

Weight                                   Increase                       Increase

Weight                                   Decrease                     Decrease

Power                                     Increase                      Increase1 

Chassis Reinforcem.              Street                             None

Chassis Reinforcem.               Sport                        Decrease2

Chassis Reinforcem.               Race                         Decrease3 

Only in special cases, see below

Reduce ARB stiffness by 3%

3 Reduce ARB stiffness by 6%

High Power Cars

Cars with very high power (>=800hp for production cars or >=1.5*stock power for race cars) require additional ARB stiffness to stabilize the car. In this case simply doubling of the ARB values is required.

Springs

Springs control the weight transition during directional changes and between front and rear wheels during acceleration and braking. Softer springs provide more grip but can lead to sluggish car behaviour during directional changes or locking front wheels under braking and when setup too soft. Stiffer springs provide more control but can lead to harsh unpredictable car behaviour during directional changes or wheel spin when accelerating when setup too stiff.

Spring rates need to be setup in relation to car weight, weight distribution and chassis / suspension stiffness. More weight requires stiffer springs and more flexible chassis / suspension require higher spring rates on the non driven wheels (front for RWD) and lower spring rates on driven wheels (rear for RWD).

Distribution of front and rear spring rates is related to weight distribution, so cars with more front weight will require also higher front spring rates. As with ARBs this is not a simple 1:1 distribution according to weight distribution as for instance the drive wheels are usually run with lower springs rates in relation to non driven wheels to reduce wheel spin. 

As others suggested a good range is between 1/3 and 1/2 of the slider though there are exceptions where you need to run above or below that range.

These are the ranges for spring rates I usually operate (given in percentage of distributed front / rear weight) on RWD cars:

Car Type                          Front Spring Rate           Rear Spring Rate

Production Car                        86-100%                             56-81%

High Performance Car           85-93%                               63-84%

Race Car                                    83-93%                               59-85%

Prototype Race Car                 79-83%                               70-89%

Open Wheel Car                      43-58%                               10-24%

Open Wheel Race Car              9-54%                                14-51%

 

The ranges given account for different body types within the car type.

Example: RWD production car with 3000lbs @ 52% wd 

front spring rate would be between: 

3000 / 2 * 52% * 86% = 670 and 

3000 / 2 * 52% * 100% = 780  depending on body type.

For FWD cars simply swap front and rear spring rates. For AWD cars use RWD rear spring rate for front springs and add 0.05-0.9% offset for rear spring rate depending on body type. Older cars require higher offset than modern cars and race cars require a lower offset than productions cars.

As with ARBs keep in my mind that adding chassis reinforcement upgrade increases chassis rigidity, i.e. springs should be reduced accordingly.

Increasing tire width also requires springs to be increased to compensate for added grip. For each 10 inch increase in tire width increase springs by 0.5%. This is usually in the range of 0-5lb depending on increased tire width.

Also when adding aero springs need to be increased to compensate for added downforce. The exact impact of downforce on springs is not simple to determine as it not only involves the amount of added downforce but must also take into account the deviation of downforce from balanced downforce level.

Balanced Downforce

Balanced downforce levels depend on the cars weight distribution and are distributed around the cars aerodynamic ideal front weight distribution of 47%. For a car with 47% front weight distribution and a Standard Forza race aero kit (50-100/75-200) balanced downforce is achieved when downforce sliders are aligned, e.g. 50/75, 75/137 or 100/200. For cars with higher front weight distribution rear downforce slider must be higher than front downforce slider depending on how much the cars front weight distribution differs from 47%. Likewise for cars with lower front weight distribution rear downforce slider must be lower than front downforce slider to achieve balanced downforce levels. For each %1 difference of car weight distribution from 47% rear downforce must be increased or decreased by 1.866667lb.  So balanced downforce levels kind of equalize the deviation of the cars front weight distribution from the ideal 47% front weight distribution by increasing or decreasing rear downforce in relation to front downforce.

 

Usually balanced downforce only affects rear downforce but if balanced aero would require to increase rear downforce beyond maximum possible rear downforce, rear downforce is set to maximum and front aero is reduced instead. Likewise if balanced downforce would require to reduce rear downforce lower than minimum allowed front downforce, rear downforce is set to minimum and front downforce is increased instead.

Example: FWD production car with 64% wd, Standard Forza aerokit (50-100/75-200):

Balanced downforce for 75lb front aero:

137 + (64-47) * 1.866667 = 168.7339 --> 169lb

To sum up the impact of downforce on springs consist of two factors:

  • amount of added downforce: for each 10lb added front downforce increase front springs by 0.5, for each 25lb added rear downforce increase rear springs by 0.5

  • deviation from balanced downforce: for each 2lb difference of front / rear downforce from balanced front / rear downforce increase or decrease front / rear springs by 0.5

Keep in mind that not only adjustable race aero kits provide downforce that has an impact on springs but also non-adjustable stock, street or sports aero kits, albeit much more subtle.

Aero Kit                            Downforce

Stock Front Bumper              10lb

Street Front Bumper             10lb

Sport Front Bumper              40lb

Stock Rear Wing1                   25lb

Street Rear Wing                    25lb

Sport Rear Wing                     70lb

Stock Rear Bumper                25lb

Street Rear Bumper               25lb

Sport Rear Bumper                50lb

Race Rear Bumper                 70lb                 

1 Many cars don't have a stock rear wing, so in this case there is no downforce applied

Example: FWD production car with 2198lb, 64% wd, stock aero (10/25/25), front springs: 563.9, rear springs 370.9

Adding front and rear race aero kit with stock downforce 75/137 (balanced downforce for 64% wd is 75/169)

Front spring offset: (75-10)/10=6.5, 6.5*0.5=3.25

Rear spring offset: (137-25)/25=4.48, 4.48*0.5=2.24,(137-169)/2=-16,-16*0.5=-8, total rear spring offset: 2.24-8=-5.76

New front springs: 563.9 + 3.25 = 567.15

New rear springs: 370.9 - 5.76 = 365.14

Car Property                 Change                 Effect on Springs

Weight                             Increase                       Increase

Weight                            Decrease                      Decrease

Power                              Increase                        Increase1 

Front Tire Width            Increase              Increase front springs

Front Tire Width           Decrease             Decrease front springs

Rear Tire Width              Increase              Increase rear springs

Rear Tire Width             Decrease             Decrease rear springs

Front Downforce           Increase              Increase front springs

Front Downforce           Decrease            Decrease front springs

Rear Downforce             Increase              Increase rear springs

Rear Downforce             Decrease            Decrease rear springs

Chassis Reinforcem.        Street                            None

Chassis Reinforcem.        Sport                Decrease front springs2

Chassis Reinforcem.         Race                Decrease front springs3

Only in special cases, see below

Reduce front spring rate by 2.75%

Reduce front spring rate by 5.5%

High Power Cars

Cars with very high power (>=800hp for production cars or >=1.5*stock power for race cars) require additional ARB stiffness to stabilize the car. In this case simply doubling of the ARB values is required.

Ride Height

Ride height works as an additional stabilizing factor like aero and a higher ride height generally allows you to brake and accelerate faster. However raising ride height also raises the center of mass which hurts turning. So there is a sweet spot for setting up the ride height which I call optimal ride height.

The optimal ride height for a car is the lowest ride height possible that is not lower than the car types minimum ride height. Each car type has a minimum ride height that is required to have enough suspension travel during cornering. 

In general for older cars the minimum ride height is higher than for modern cars and for race cars the minimum ride height is lower than for productions cars.

Always keep front and rear ride height level , i.e. keep the sliders aligned. Having front and rear ride height sliders unaligned  creates over- or understeer effects and is only required when tuning for grip, speed or specific tracks.

Car Type                                 Min. Ride Height

Production Car                               4.0-6.0 

Open Wheel Car                             4.0-6.0

High Performance Car                  3.0-4.0

Race Car                                          3.0-5.0 

Prototype Race Car                        2.5-3.5 

Open Wheel Race Car                   2.5-4.5

The ranges given are for different body types within the car type.

There are two exceptions:

 

1) Set ride height to lowest if the front ride height can be set below 2 inches

2) Set ride height to highest if the maximum front ride height is below the minimum ride height

Note: Minimum ride height works in 0.5 increments and is most of the time an integer number.

Dampers

Getting damping right is one of the hardest parts when it comes to tuning and from my experience separates good tunes from excellent tunes.

 

Dampers control weight transition during directional changes and while turning. Bump helps you in initiating a directional change or entering a turn while rebound helps to maintain the speed while turning.

 

Setting bump too soft can result into corner diving while braking and entering a turn. Also too soft bump can make the car unresponsive to directional changes and provoking oscillation of the front springs making the car very bouncy. Setting bump too stiff can result in understeer while entering a turn. It also can create rear tire spin while accelerating out of a corner.

 

Setting rebound too soft makes the car oversteer on corner entry and generally unresponsive to directional changes. Setting rebound to stiff creates understeer during corner entry and while turning.

Generally damping stiffness must be set in relation to chassis / suspension stiffness, i.e. a car with more rigid chassis / suspension requires higher overall damping stiffness. Damping stiffness is the sum of bump and rebound.

 

Bump has a direct relation to front car weight and suspension stiffness, i.e. the higher the cars front weight is the higher the bump is required to avoid diving on turn-in. Also cars with stiffer suspension require less bump whereas older cars with softer suspension require stiffer bump. 

Rebound has a direct relation to chassis stiffness, the more rigid the chassis is the higher the rebound must be set. 

Rebound should be most of the time higher than Bump. Exception are open wheel cars where rebound and bump are required to be leveled due to the unique suspension geometry of open wheel cars.

Car Type                        Damping Stiffness         Rebound           Bump

Production Car                        10.0-14.0                   6-0-8.0              4.0-6.0

High Performance Car           12.0-14.0                   8.0-9.0              4.0-5.0

Race Car                                   11.5-14.0                   7.5-9.0              4.0-5.0

Prototype Race Car                12.5-16.0                   8.5-11.0            4.0-5.0

Open Wheel Race Car           15.0-26.0                   7.5-13.0           7.5-13.0

Open Wheel Car                       8.0-15.0                   4.0-7.5              4.0-7.5

 

The ranges given account for different body types within the car type and weight ranges.

AWD and FWD cars require lower bump and higher rebound than RWD cars to combat inherent understeer. For AWD cars use RWD damping and increase rebound by 0.3 and reduce bump by 0.3. For FWD cars use RWD damping and increase rebound by 0.5 and reduce bump by 0.5. 

The relation between front and rear dampers should mirror the relation of front and rear spring rates, i.e. if the front spring rate is lower than the rear spring percentage rate the front dampers should also be lower than the rear dampers and vice versa. 

Front-Rear Spring Rate      Front-Rear Rebound        Front-Rear Bump

Difference                              Difference                          Difference

<1.5%                                                0.2                                         0.1

1.5-35%                                             0.3                                         0.2

36-40%                                              0.6                                         0.4

>40%                                                 1.2                                         0.8

Example: FWD car with front spring rate 50%, rear spring rate is 80%

Spring rate difference: 50%-80% = -30%

Front rebound should be 0.3 lower than rear rebound

Front bump should be 0.2 lower than rear bump

Due to their unique suspension geometry open wheel cars require a very high rear damping independently of front and rear spring rates. For open wheel sports cars rear dampers should be 2.5 higher than front dampers. For open wheel race cars rear dampers should be 3.5 higher than front dampers.

When reducing weight bump might need to be increased and rebound need to be decreased to compensate for added front weight, for every 100lb front weight reduction rebound needs to increased by 0.1 and bump needs to be reduced by 0.1. Similarily when adding front weight, rebound has to be reduced and bump has to be increased.

When adding aero bump might need to be increased and rebound need to be decreased to compensate for added front downforce, this is usually in the range of 0.1-0.3 depending on amount of added downforce.

Car Property                Change            Effect on Rebound / Bump

Front Weight                 Increase                Decrease / Increase

Front Weight                Decrease               Increase / Decrease 

Front Downforce          Increase                Decrease / Increase

Front Downforce         Decrease                Increase / Decrease 

Brakes

Brake tuning is the only setting that is not car specific. I always run 48% front brake distribution with 125% brake pressure which seems like a sweet spot between braking before corners and braking while cornering (also know as trail braking). 

Car Type         Brake Distribution        Brake Pressure

All                                48%                                  125%

Differential

Differential is for fine tuning corner entry and exit behaviour. Also a good ratio between accel and diff supports smooth cornering without unnecessary corrections.

 

Generally older cars require lower accel and higher decel than modern cars and race cars require higher accel and lower decel than production cars

 

RWD Cars

68/35 is good middle ground for modern production cars, increase accel and/or decrease decel for cars with more rigid chassis/suspension (i.e. super cars, GT race cars etc.), decrease accel and/or increase decel for cars with more flexible chasssis/suspension (i.e. older cars).

Car Type                                Accel               Decel

Production Car                      64-68%            34-36%

High Performance Car           70%                  34%

Race Car                                 68-72%            34-35%

Prototype Race Car               94-98%               0%

Open Wheel Race Car          12-20%                0%

Open Wheel Car                    26-30%            10-12%

The ranges given account for different body types within the car type.

AWD Cars

For AWD cars use the RWD diff settings as basis and set them according to following scheme:

Front Accel:  RWD Accel 

Front Decel:       0%

Rear Accel:      100%

Rear Decel: RWD Decel

Diff Distr.:   RWD Accel + 2%
 

FWD Cars

48/0 is good middle ground for modern production cars, increase accel for cars with more rigid chassis/suspension, decrease accel for cars with more flexible chassis/suspension

Car Type                                Accel               Decel

Production Car                      46-48%               0%

Race Car                                    52%                  0%

Prototype Race Car                  78%                 0%

The ranges given are for the different body types within the car type.                   

Note: For some reasons increasing and decreasing accel only works good in 2-step increments (i.e. accel should always be an even number) while for decel 1-step increments are just fine.

Gearing

For general tuning only adjustment of the final drive is required. Tuning single gears ratios is only required when tuning for specific tracks.

Setting up the final drive depends solely on the cars power and the type of installed gearbox. The general logic here is a car with more power requires a lower final drive and vice versa.

There are two types of gearboxes:

  • Standard Forza race gearbox: 6-speed race gearbox with following gear ratios: 2.89/1.99/1.49/1.16/0.94/0.78

  • Custom race gear box (any other race gearbox)

The general principle here is that the installed gearbox is calibrated to the cars stock power. If the car uses the standard Forza race gearbox, the gearing is scaled to a reference car with a stock power of 400hp and a stock final drive of 4.25. If the car uses a custom race gearbox the gearing is scaled to the cars stock power and stock final drive.

Being calibrated means the cars stock gearing is already optimal for the cars stock power. You only have to change the final drive if you change the cars power via engine upgrades. For each 6hp increase over stock power you need to decrease the final drive by 0.01. Likewise for each 6hp decrease over stock power you need to increase the final drive by 0.01.

Note: Cars with drivetrain swaps will always automatically be equipped with a Standard Forza gearbox. 

Car Property            Change               Effect on Final Drive

Power                         Increase                       Decrease

Power                        Decrease                       Increase

Drivetrain            Drivetrain Swap         Increase/Decrease1

1 Only for cars with stock custom gearbox

Cars with Standard Forza gearbox

For cars with a standard Forza race gearbox subtract the cars power from 400hp (the reference cars stock power), divide it by 6hp, multiply it by 0.01 and add it to 4.25 (the reference cars stock final drive) to get the required final drive.

Example: 325hp
400hp-325hp=75hp
75hp/6hp=12.5

12.5*0.01=0.125
4.25+0.125=4.375 --> Final Drive: 4.38

Cars with Standard Forza gearbox and 3, 4 or 5-speed sport gearbox

 

For cars with a Standard Forza gearbox, that use a 5-speed sport gearbox the reference stock final drive for sport transmission is 4.00.

For cars with a Standard Forza gearbox, that use a 4-speed sport gearbox the reference stock final drive for sport transmission is 4.75.

For cars with a Standard Forza gearbox, that use a 3-speed sport gearbox the reference stock final drive for sport transmission is 4.50.

Low Gearing Cars with Standard Forza gearbox

There are some cars (like the 1953 Chevrolet Corvette) which require a lower gearing than usual. These are all cars with a standard Forza gearbox and a stock final drive <=3.25 (either on sport or race gearbox). For these low gearing cars the reference stock final drive as calculated above needs to be reduced by 1.00.

High Power Cars with Standard Forza gearbox

Cars with Standard Forza aero kit and very high power (>=800hp) that would potentially exceed the available final drive range simply require to half the cars power and do the above calculation.

 

Low Power Cars with Standard Forza gearbox

Cars with Standard Forza aero kit and very low power (<=200hp) that would potentially exceed the available final drive range simply require to double the cars power and do the above calculation. 

Cars with Custom Gearbox


For cars with a custom race gearbox subtract the cars power from the cars stock power, divide it by 6hp, multiply it by 0.01 and add it to the cars stock final drive to get the required final drive.

Example: 325hp, stock power 300hp, stock final drive 3.30
300hp-325hp=-25hp
-25hp/600=-0.04166667
3.30-0.04166667=3.25833333 --> Final Drive: 3.26

Race Cars with no Engine Upgrades

Race cars that don't offer any engine upgrades like F1 cars or IndyCars would never require an adjustment of the final drive since you're always running them on stock power. For these cars you need to reduce the cars stock final drive by 0.75 in order to work best. 

Aero

Aero tuning in Forza is the most complex topic as it involves many different factors. As opposed to gear tuning it's almost always required since on most tracks you need adjustable race aero kits to be really competitive.

Lets start with the general pattern on how to setup downforce levels depending on the cars drivetrain:

  • RWD/AWD: front max / rear max

  • FWD (drivetrain swaps available): front max / rear min

  • FWD (no drivetrain swaps available): front max / rear max

Setting up to specific downforce values depends solely on the cars weight and the type of installed race aero kit. The general logic here is the lighter the car is the less downforce is required and vice versa. If downforce levels are setup too low related to cars weight you will lose traction while cornering. If downforce levels are setup too high related to cars weight the car will become unresponsive and more difficult during cornering.

There are two types of race aero kits:

  • Standard Forza race aero kit: adjustable aero kit with front downforce range 50-100 and rear downforce range 75-200

  • Custom race aero kit  (any other adjustable aero kit)

The general principle here is that the installed race aero kit is scaled (or calibrated) to the cars stock weight. If the car uses the standard Forza race aero kit, the aero kit is scaled to a reference car with a stock weight of 3000lb. If the car uses a custom race aero kit the aero kit is scaled to the cars stock weight.

Being calibrated means the aero kits maximum downforce levels (RWD/AWD) or maximum/minimum downforce levels (FWD) are optimal for the cars stock weight. You only have to change downforce levels if you reduce the car weight via weight reduction or other weight reducing parts. For each 100lb decrease over stock weight you need to decrease downforce levels by 1.

However since possible drivetrain swaps can actually increase the cars weight as compared to cars stock weight there is a headroom of 300lb on top of the cars stock weight before reduction of downforce levels is required. That means for most cars that offer drivetrain swaps you have to reduce the car weight over 400lb as compared to cars stock weight before reduction of downforce levels is required.

Car Property        Change           Effect on Downforce

Weight                    Increase                    Increase

Weight                   Decrease                   Decrease

Power                     Increase                    Increase1

Only in special cases, see below

Cars with Standard Forza Race Aero Kit

For cars with a standard Forza race aero kit you have to subtract the cars weight from 2700lb (the reference cars stock weight - 300lb headroom for drivetrain swaps if available), divide it by 100lb and add it to maximum downforce levels (or maximum / minimum downforce levels in case of FWD).

Example: FWD car, 2900lb, drivetrain swaps available

2900-(3000-300) = 200

200/100=-2

Front: 100+2=102 --> 100 (maximum downforce), Rear: 75+2=77

Example: RWD car, 2500lb, no drivetrain swaps available

2500-3000 = -500

-500/100=-5

Front: 100-5=95 Rear: 200-5=195

High Power Cars with Standard Forza Race Aero Kit

Usually only car weight determines required downforce levels but for cars with standard Forza race aero kit and very high power (>=800hp) extra downforce is required to stabilize the car. In this case multiplying the maximum downforce levels (or maximum / minimum in case of FWD) with 1.5 is required before performing the above calculation. 

Example: FWD car, 2900lb, 800 hp, drivetrain swaps available

2900-(3000-300) = 200

200/100=-2

Front: (100*1.5)-2=148 --> 100 (maximum downforce), Rear: (75*1.5)-2=112.5 --> 113

Low Power Cars with Standard Forza Race Aero Kit

Likewise cars with standard Forza race aero kit and with very low power (<=200hp) don't require as much downforce as usual. Here you have to multiply front aero downforce with 0.7 and rear downforce with 0.4 after you performed the above calculation.

Example: FWD car, 2900lb, 200 hp, drivetrain swaps available

2900-(3000-300) = 200

200/100=-2

Front: 100+2=102, 102*0.7=71.4 --> 71, Rear: 75+2=77, 77*0.4=30.8 --> 75 (minimum downforce)

Cars with Custom Race Aero Kit

For cars with a custom race aero kit you have to subtract the cars weight from the cars stock weight - 300lb (the headroom for drivetrain swaps if available), divide it by 100lb and add it to maximum downforce levels (or maximum / minimum downforce levels in case of FWD).

Example: FWD car, 2500lb, stock weight 3047, maximum/minimum downforce levels 155/158, drivetrain swaps available

2500lb-(3047-300) = -247

-247/100=-2.47

Front: 155-2.47=152.53 --> 153, Rear: 158-2.47=155.53 --> 158 (minimum downforce)

Example: RWD car, 2100lb, stock weight 2745, maximum downforce levels 392/570,  no drivetrain swaps available

2100-2745 = -645

-645/100=-6.45

Front: 392-6.45=385.55 --> 386, Rear: 570-6.45=363.55 --> 364

Cars with Custom Race Aero Kit and High Rear Aero

For cars with custom race aero kit and very high rear downforce (max. rear downforce > 3* max. front downforce)  the rear downforce should never exceed 3*front downforce. Simply cap rear downforce at 3*front downforce.

A prominent example is 1995 Ferrari F50 with a maximum front downforce of 100lb and a maximum rear downforce of 305lb. In this case rear downforce should not exceed 300lb for this car except when tuning for grip tracks which is covered in part 3.

 

High Power Cars with Custom Race Aero Kit

Usually only car weight determines required downforce levels but for cars with very high power (>=1.5*stock power) extra downforce is required to stabilize the car. In this case multiplying the maximum downforce levels (or maximum / minimum in case of FWD) with 1.5 is required before performing the above calculation. 

Example: FWD car, 2500lb, 460hp, stock weight 3047, stock power 306hp, maximum/minimum downforce levels 155/158, drivetrain swaps available

2500lb-(3047-300) = -247

-247/100=-2.47

Front: (155*1.5)-2.47=230.03 --> 230, Rear: (158*1.5)-2.47=234.53 --> 235