top of page

Forza Motorsport Tuning Guide

Part 2 - General Tuning

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

 

This also serves a basis for grip and speed tuning as well as track specific tuning which will be covered in Part 3 and Part 4, so make sure to read this first before advancing to track specific tuning.

Understanding Tuning Relevant Car Properties

As in Part 1 explained car type and body type are the most important factors when it comes to tuning, but there are also other individual car properties that have great impact on the tuning, most notable are drivetrain, power and weight.

The following table gives an overview which car property affects which tuning area. Please refer to the related section in the tuning guide for detailed explanations.

Car Property           Tires        Gearing       Alignment         ARBs         Springs         Dampers       Geometry       Aero        Brakes       Diff

                                                                                           

Car Type                      ✓                                                                                                                                                                                 ✓                 

Body Type                                                                 ✓                     ✓                  ✓                     ✓                                                            

Drive Type                                                                                         ✓                  ✓                     ✓                                            ✓                                 ✓

Engine                                             ✓                       ✓                                                                  ✓                       ✓ 

Power                                              ✓                       ✓                      ✓                  ✓                    ✓                       ✓                  ✓            

Weight                         ✓                                                                    ✓                  ✓                   ✓                                             ✓                    

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Chassis Reinf.                                                           ✓                      ✓                  ✓                   ✓                        ✓                                    

Weight Reduction      ✓                                           ✓                      ✓                  ✓                                              ✓                                                      ✓ 

Ballast                          ✓                                           ✓                      ✓                  ✓                                              ✓               

Tire Compound          ✓         

Tire Width                                                                 ✓                                           ✓

Rims                             ✓                                           ✓                      ✓                  ✓                                              ✓                                              

Aero Kits                      ✓                                                                                         ✓                    ✓                                            ✓

 ✓   New in Forza Motorsport (2023) 

Tires

Tires

Tire pressure tuning in the new Forza Motorsport has become more complex and now depends on a number of factors such as tire compound, vehicle weight, aerodynamic downforce and rim size.

Tire pressure tuning first and foremost 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.

Generally front and rear tire pressures should be the same. Having different tire pressures on front and rear tires creates over- or understeer effects and is only required when tuning for speed, grip or specific tracks.

Tire Compound                Tire Pressure

Stock                                           28.0 

Street                                          28.0

Sport                                           28.5 

Race                                            29.0

Slicks                                           29.5 

-----------------------------------------------------------

Early Modern Race  New         28.0         

Vintage Sport  New                   24.5 

Vintage Race                              25.0 

Vintage Slicks  New                   25.5 

-----------------------------------------------------------

Off-road Race                            23.0  

-----------------------------------------------------------

Drag                                            17.5 

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

Note that stock tire compound for vintage race cars is usually Vintage Race, but some vintage GP race cars are equipped with Vintage Slicks (only Race and Drag compound available as upgrade). Also vintage race cars use Vintage Sport tires instead of regular Sport compound.

Race Cars and High Performance Cars

Aside from tire compound tire pressure tuning also depends on the type of car as high performance cars and race cars require higher tire pressure for improved control than street or sports cars. That means for high performance cars and race cars you need to add an additional 0.5 psi on top of the base tire pressure for best tire performance.

Car Type                            Tire Pressure Offset

High Performance Car                 +0.5

Race Car                                         +0.5

Prototype Race Car                      +0.5

GP Race Car                                   +0.5

Heavy Cars 

Cars with a weight that exceeds 3000 lbs need increased tire pressure to compensate for high weight affecting tire contact patch size. For each 500 lb increase over 2500 lb an 5 psi tire pressure increase is required for best handling.

Weight            Tire Pressure Offset 

3000-3499                    +5.0     Changed 

3500-3999                  +10.0     Changed 

4000-4499                  +15.0     Changed 

4500-4999                  +20.0     Changed 

5000-5499                  +25.0     Changed 

Light Cars 

Light weight cars with a weight under 2000 lbs need decreased tire pressure to compensate for low weight affecting tire contact patch size. For each 500 lb decrease over 2499 lb an 5 psi tire pressure decrease is required for best handling.

Weight            Tire Pressure Offset 

1500-1999                    -5.0   

1000-1499                   -10.0

500-999                       -15.0

0-499                            -20.0

Cars without Race Weight Reduction  New 

For cars that are not equipped with full race weight reduction require lower tire pressure tuning depending on installed weight reduction upgrade for best handling.

Weight Reduction       Tire Pressure Offset 

Stock                                           -4.5  

Street                                          -3.0

Sport                                           -1.5

Cars with Heavy Ballast  New 

For cars that are equipped with medium heavy, heavy or extra heavy ballast require higher tire pressure tuning depending on installed ballast upgrade for best handling.

Ballast                            Tire Pressure Offset 

Medium Heavy                          +0.5  

Heavy                                          +1.0

Extra Heavy                                +1.5

Cars with Adjustable Downforce  New 

For cars that are equipped with adjustable front bumper or rear wing downforce levels now also need to be considered for tire pressure tuning. For each 100lb front downforce front tire pressure must be increased by 0.5 psi. Likewise For each 100lb rear downforce rear tire pressure must be increased by 0.5 psi for best handling.

Cars with Big Rims  New 

For cars that are equipped with very big rims (>18 ") rim size now also need to be considered for tire pressure tuning. For each 1" increase over 18" tire pressure must be decreased by 1.0 psi for the affected tires. 

Rim Size         Tire Pressure Offset 

19"                                 -1.0   

20"                                 -2.0

21"                                 -3.0

22"                                 -4.0

Alignment

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.

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

Car Type                               Usual Camber Range

Race Car                                       -2.5 to -1.5

Prototype Race Car                     -2.5 to -0.5

GP Race Car                                 -3.0 to -0.5

------------------------------------------------------------

Street Car                                     -3.0 to  0.0

Sports Car                                    -3.0 to  0.0

High Performance Car               -2.5 to -1.0

------------------------------------------------------------

Rally Sports Car                          -3.0 to  0.0

------------------------------------------------------------

Off-road Car                                -3.0 to  0.0

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

Relevant Car Upgrades

Tire width directly influence camber settings. This is due to wider tires increase contact patch, so for optimal grip camber needs to be reduced to compensate for added contact patch size.

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

Cars with Extreme Power  New 

 

Cars that have extreme power (>=800 hp)  require less camber depending on installed chassis reinforcement upgrade for best handling.

Chassis Reinforcement            Camber Offset

Stock                                                       +1.5

Street                                                      +1.5

Sport                                                       +1.0

Race                                                        +0.5

Modern Cars with High Torque Engine Swaps  New 

 

Modern cars (built 1980 or later) that use a high torque engine swap (ex. 3.7L V6) require less camber depending on installed chassis reinforcement upgrade for best handling.

Chassis Reinforcement            Camber Offset

Stock                                                       +1.5

Street                                                      +1.5

Sport                                                       +1.0

Race                                                        +0.5

High Torque Vintage Cars  New 

Vintage cars (cars built before 1980) that have an engine with high stock torque (>=250lb/ft) or that use a high torque engine swap (ex. 3.7L V6) require more camber depending on installed chassis reinforcement upgrade for best handling.

Chassis Reinforcement            Camber Offset

Stock                                                       -1.5

Street                                                      -1.5

Sport                                                       -1.0

Race                                                        -0.5

Cars without Race Weight Reduction  New 

For cars that are not equipped with full race weight reduction require lower camber depending on installed weight reduction upgrade for best handling.

Weight Reduction          Camber Offset 

Stock                                            +4.5  

Street                                           +3.0

Sport                                            +1.5

Cars with Heavy Ballast  New 

For cars that are equipped with medium heavy, heavy or extra heavy ballast require higher camber (more camber) depending on installed ballast upgrade for best handling.

Ballast                      Camber Offset 

Medium Heavy                   -0.5  

Heavy                                   -1.0

Extra Heavy                         -1.5

Cars with Heavy Rims   New 

For cars that are equipped with heavy rims (weight class 3 - 5)  require less camber depending on rim weight class  for best handling. Note that this also applies to cars with stock rims.

Rim Weight Class                   Camber Offset      

5 (Heaviest)                                        +1.5                   

4                                                           +1.0            

3                                                           +0.5           

Cars with Rim Size Upgrades   New 

For cars that are equipped with front or rear rim size upgrades require more camber on the affected car side (front / rear) depending on installed chassis reinforcement upgrade and rim size upgrade for best handling. 

                                                         Max Rim Size          Max Rim Size - 1       Max Rim Size - 2

Chassis Reinforcement            Camber Offset       Camber Offset        Camber Offset

Stock                                                       -1.5                              -1.0                            -0.5

Street                                                      -1.5                              -1.0                            -0.5

Sport                                                       -1.0                              -0.5                             0.0

Race                                                        -0.5                               0.0                             0.0

Toe

For most cars there is no need adjust toe as this creates almost always unwanted imbalance during turning.

Exceptions are older road and off-road cars that require slight rear toe-in (max. -0.3) to combat on-throttle understeer.

Car Type                                  Front Toe         Rear Toe

Race Car                                          0.0                    0.0

Prototype Race Car                       0.0                    0.0 

GP Race Car                                    0.0                    0.0 

-----------------------------------------------------------------------------

Street Car                                        0.0                -0.3-0.0

Sports Car                                       0.0                -0.3-0.0

High Performance Car                  0.0                    0.0

-----------------------------------------------------------------------------

Rally Sports Car                             0.0                -0.3-0.0

-----------------------------------------------------------------------------

Off-road Car                                   0.0                -0.3-0.0

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, race cars require lower caster than production cars and off-road cars require lower caster than road cars.

 

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 type 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

Race Car                                              4.0/5.0

Prototype Race Car                               6.0

GP Race Car                                            7.0

-----------------------------------------------------------------

Street Car                                          5.0/6.0/7.0

Sports Car                                         5.0/6.0/7.0

High Performance Car                          5.0 

-----------------------------------------------------------------

Rally Sports Car                                  5.0/6.0

-----------------------------------------------------------------

Off-road Car                                           4.0

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

Cars with Extreme Power  New 

 

Cars that have extreme power (>=800 hp) require more caster depending on installed chassis reinforcement upgrade for best handling.

Chassis Reinforcement            Caster Offset

Stock                                                       +1.5

Street                                                      +1.5

Sport                                                       +1.0

Race                                                        +0.5

Modern Cars with High Torque Engine Swaps  New 

 

Modern cars (built 1980 or later) that use a high torque engine swap (ex. 3.7L V6) require more caster depending on installed chassis reinforcement upgrade for best handling.

Chassis Reinforcement            Caster Offset

Stock                                                       +1.5

Street                                                      +1.5

Sport                                                       +1.0

Race                                                        +0.5

High Torque Vintage Cars  New 

Vintage cars (cars built before 1980) that have an engine with high stock torque (>=250lb/ft) or that use a high torque engine swap (ex. 3.7L V6) require lower caster depending on installed chassis reinforcement upgrade for best handling. 

Chassis Reinforcement            Caster Offset

Stock                                                       -1.5

Street                                                      -1.5

Sport                                                       -1.0

Race                                                        -0.5

Cars without Race Weight Reduction  New 

For cars that that are not equipped with full race weight reduction require higher caster depending on installed weight reduction upgrade for best handling.

Weight Reduction        Caster Offset 

Stock                                         +4.5  

Street                                        +3.0

Sport                                         +1.5

Cars with Heavy Ballast  New 

For cars that are equipped with medium heavy, heavy or extra heavy ballast require lower caster depending on installed ballast upgrade for best handling.

Ballast                        Caster Offset 

Medium Heavy                   -0.5  

Heavy                                   -1.0

Extra Heavy                         -1.5

Cars with Heavy Rims   New 

For cars that are equipped with heavy rims (weight class 3 - 5)  require more caster depending on rim weight class  for best handling. Note that this also applies to cars with stock rims.

Rim Weight Class                    Caster Offset      

5 (Heaviest)                                        +1.5                   

4                                                           +1.0            

3                                                           +0.5           

Cars with Front Rim Size Upgrade   New 

For cars that are equipped with front  rim size upgrades require more caster depending on installed chassis reinforcement upgrade and rim size upgrade for best handling. 

                                                         Max Rim Size          Max Rim Size - 1       Max Rim Size - 2

Chassis Reinforcement             Caster Offset          Caster Offset          Caster Offset

Stock                                                       -1.5                              -1.0                            -0.5

Street                                                      -1.5                              -1.0                            -0.5

Sport                                                       -1.0                              -0.5                             0.0

Race                                                        -0.5                               0.0                             0.0

Anti-roll Bars

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 road 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 road 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.

Car Type                         ARB Stiffness         ARB Distribution

Race Car                               35-62%                      0.35-0.80

Prototype Race Car             80-89%                      0.25-0.35

GP Race Car                          84-90%                      0.15-0.35

---------------------------------------------------------------------------------------

Street Car                             63-66%                      0.98-1.50

Sports Car                            61-65%                      0.66-1.00

High Performance Car       40-55%                      0.55-0.65

---------------------------------------------------------------------------------------

Rally Sports Car                   61-65%                      0.66-1.00

---------------------------------------------------------------------------------------

Off-road Car                         63-65%                      1.00-2.95

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

ARB Stiffness

ARB stiffness is a metric to calculate ARB base values based on the cars weight and a weight distribution of 50%.

The formula to determine ARBs for a given ARB stiffness and a weight distribution of 50% looks like this:

Base ARB = (Weight / 2) / (200 - 200 * ARB stiffness)

Example: Street Car with 2500 lb and ARB stiffness of 63% and ARB distribution of 1.00:

Base ARB = (2500 / 2) / (200 - 200 * 63%) = 16.89 

 

Depending on the cars weight distribution and ARB distribution front and rear ARBs are distributed around the ARB base value:

Weight Distribution              Front ARB           Rear ARB

          52%                                     17.89                  15.89

          51%                                     17.39                  16.39

          50%                                     16.89                  16.89

          49%                                     16.39                  17.39

          48%                                     15.89                  17.89

FWD Cars

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 road cars around 3000lbs. 

Example: ARBs for a modern FWD street 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

AWD Cars

AWD cars require a lower ARB distribution 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.  

Cars with Extreme Power

 

Cars that have extreme power (>=800 hp) require higher ARB stiffness for best handling. In this case simply doubling of the ARB values is required.

Relevant Car Upgrades

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%

Cars without Race Weight Reduction  New 

For cars that are not equipped with full race weight reduction require higher ARB stiffness depending on installed weight reduction upgrade for best handling.

Weight Reduction       ARB Stiffness Offset 

Stock                                            +12% 

Street                                           +24%

Sport                                            +36%

Cars with Heavy Ballast  New 

For cars that are equipped with medium heavy, heavy or extra heavy ballast require higher ARB stiffness depending on installed ballast upgrade for best handling.

Ballast                        ARB Stiffness Offset 

Medium Heavy                       +6% 

Heavy                                      +12%

Extra Heavy                            +24%

Cars with Heavy Rims   New 

For cars that are equipped with heavy rims (weight class 3 - 5)  require increased ARB stiffness depending on rim weight class  for best handling. Note that this also applies to cars with stock rims.

Rim Weight Class              ARB Stiffness Offset      

5 (Heaviest)                                        +24%                   

4                                                           +12%            

3                                                            +6%          

Cars with Rim Size Upgrades   New 

For cars that are equipped with front or rear rim size upgrades require increased ARB stiffness on the affected car side (front / rear) depending on installed chassis reinforcement upgrade and rim size upgrade for best handling. 

                                                         Max Rim Size                 Max Rim Size - 1              Max Rim Size - 2

Chassis Reinforcement      ARB Stiffness Offset     ARB Stiffness Offset     ARB Stiffness Offset

Stock                                                       +24%                                 +12%                                  +6% 

Street                                                      +24%                                 +12%                                  +6%

Sport                                                       +12%                                  +6%                                     0%

Race                                                        +12%                                    0%                                      0%

Springs

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. 

Each body type requires a distinctive front and rear spring rate percentage that works best with its inherent chassis and suspension stiffness. Generally speaking older cars require higher front spring rate percentage and lower rear spring rate percentage than modern cars while race cars require lower front spring rate percentage and higher rear spring rate percentage than production cars.

Car Type                          Front Spring Rate           Rear Spring Rate

                                                    (RWD)                                 (RWD)

Race Car                                    83-93%                               59-85%

Prototype Race Car                  82-93%                               49-89%

GP Race Race Car                    80-104%                              10-90%

-------------------------------------------------------------------------------------------------

Street Car                                 93-100%                             57-80%

Sports Car                                 87-98%                               58-80%

High Performance Car            85-93%                               63-84%

-------------------------------------------------------------------------------------------------

Rally Sports Car                        87-98%                               58-80%

-------------------------------------------------------------------------------------------------

Off-road Car                            94-100%                              57-80%

 

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

Example: RWD street car with 3000lbs @ 52% weight distribution 

front springs would be between: 

3000 / 2 * 52% * 93% = 725 and 

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

AWD and FWD Cars

For AWD cars use the same spring rates as RWD cars. for FWD cars simply swap front and rear spring rates.

Cars with Extreme Power

 

Cars that have extreme power (>=800 hp) require higher spring stiffness for best handling. In this case simply doubling of the spring rates is required.

Relevant Car Upgrades

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. However 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.

Car Property                 Change                 Effect on Springs

Weight                             Increase                       Increase

Weight                            Decrease                      Decrease

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 springs1

Chassis Reinforcem.         Race                Decrease front springs2

Reduce front spring rate by 2.75%

Reduce front spring rate by 5.5%

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

Balanced rear downforce for 75lb front downforce:

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 road 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

Cars without Race Weight Reduction  New 

For cars that are not equipped with full race weight reduction require lower spring stiffness depending on installed weight reduction upgrade for best handling.

Weight Reduction      Spring Stiffness Offset 

Stock                                              -36% 

Street                                             -24%

Sport                                              -12%

Cars with Heavy Ballast  New 

For cars that are equipped with medium heavy, heavy or extra heavy ballast require lower spring stiffness depending on installed ballast upgrade for best handling.

Ballast                        Spring Stiffness Offset 

Medium Heavy                         -6% 

Heavy                                        -12%

Extra Heavy                              -24%

Cars with Rim Size Upgrades   New 

For cars that are equipped with front or rear rim size upgrades require increased spring stiffness on the affected car side (front / rear) depending on installed chassis reinforcement upgrade and rim size upgrade for best handling. 

                                                         Max Rim Size                     Max Rim Size - 1                  Max Rim Size - 2

Chassis Reinforcement      Spring Stiffness Offset     Spring Stiffness Offset     Spring Stiffness Offset

Stock                                                       +24%                                     +12%                                        +6% 

Street                                                      +24%                                     +12%                                        +6%

Sport                                                       +12%                                      +6%                                           0%

Race                                                        +12%                                        0%                                            0%

Ride Height

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

Race Car                                          3.0-5.0

Prototype Race Car                        2.5-3.5 

GP Race Car                                    2.5-4.5

------------------------------------------------------------------

Street Car                                        4.0-6.0 

Sports Car                                       4.0-6.0 

High Performance Car                  3.0-4.0

------------------------------------------------------------------

Rally Sports Car                                 4.0

------------------------------------------------------------------

Off-road Car                                   4.0-5.0 

The ranges given account 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.

Cars with Rim Size Upgrades   New 

For cars that are equipped with front or rear rim size upgrades require lower ride height on the affected wheels depending on installed chassis reinforcement upgrade and rim size upgrade for best handling. 

                                                         Max Rim Size                 Max Rim Size - 1              Max Rim Size - 2

Chassis Reinforcement         Ride Height Offset       Ride Height Offset        Ride Height Offset

Stock                                                       -1.5                                    -1.0                                   -0.5

Street                                                      -1.5                                    -1.0                                   -0.5

Sport                                                       -1.0                                    -0.5                                    0.0

Race                                                        -0.5                                     0.0                                    0.0

Suspension Geometry

Suspension Geometry  New 

Suspension geometry tuning is a completely new tuning aspect of the new Forza Motorsport. Suspension geometry is the positioning and alignment of the wheels and suspension components of a vehicle. It affects many aspects of a vehicle's performance, such as handling, stability, and tire wear

 

For general tuning the cars default suspension geometry tuning doesn't need to be changed except in special cases, see below.

Cars with Extreme Power

 

Cars that have extreme power (>= 800 hp) require higher roll center height offset and lower anti-dive / anti-squat depending on installed chassis reinforcement upgrade best handling. 

Chassis Reinforcement       Roll Center Height Offset      Anti-Dive / Anti-Squat Offset

Stock                                                          +1.2                                                    -1.5

Street                                                         +1.2                                                    -1.5

Sport                                                          +0.8                                                    -1.0

Race                                                           +0.4                                                    -0.5

Modern Cars with High Torque Engine Swaps

 

Modern cars (built 1980 or later) that use a high torque engine swap (ex. 3.7L V6) require lower roll center height offset and higher anti-dive / anti-squat depending on installed chassis reinforcement upgrade best handling. 

Chassis Reinforcement       Roll Center Height Offset      Anti-Dive / Anti-Squat Offset

Stock                                                          -1.2                                                    +1.5

Street                                                         -1.2                                                    +1.5

Sport                                                          -0.8                                                    +1.0

Race                                                           -0.4                                                    +0.5

High Torque Vintage Cars

Vintage cars (cars built before 1980) that have an engine with high stock torque (>=250lb/ft) or that use a high torque engine swap (ex. 3.7L V6) require higher roll center height offset and lower anti-dive / anti-squat depending on installed chassis reinforcement upgrade best handling.

Chassis Reinforcement       Roll Center Height Offset      Anti-Dive / Anti-Squat Offset

Stock                                                          +1.2                                                    -1.5

Street                                                         +1.2                                                    -1.5

Sport                                                          +0.8                                                    -1.0

Race                                                           +0.4                                                    -0.5

Cars without Race Weight Reduction

For cars that are not equipped with full race weight reduction require higher anti-dive and lower anti-squat depending on installed weight reduction upgrade for best handling.

Weight Reduction         Anti-Dive Offset        Anti-Squat Offset 

Stock                                       +150.0                             -150.0

Street                                      +100.0                             -100.0

Sport                                        +50.0                                -50.0

Cars with Heavy Ballast

For cars that are equipped with medium heavy, heavy or extra heavy ballast require lower anti-squat depending on installed ballast upgrade for best handling.

Ballast                        Anti-Squat Offset

Medium Heavy                    -50.0 

Heavy                                   -100.0

Extra Heavy                         -150.0

Cars with Heavy Rims

For cars that are equipped with heavy rims (weight class 3 - 5)  require a higher roll center height offset and higher anti-dive / anti-squat settings depending on rim weight class  for best handling. Note that this also applies to cars with stock rims.

Rim Weight Class                   Roll Center Height Offset         Anti-Dive / Anti-Squat Offset   

5 (Heaviest)                                                  +9.8                                                       +1.5         

4                                                                     +6.4                                                       +1.0

3                                                                     +3.2                                                       +0.5

Cars with Rim Size Upgrades

For cars that are equipped with front or rear rim size upgrades require higher roll center height offset and lower anti-dive / anti-squat on the affected car side (front / rear) depending on installed chassis reinforcement upgrade and rim size upgrade for best handling. 

                                                               Max Rim Size                                    Max Rim Size - 1                             Max Rim Size - 2

Chassis Reinforcement          Roll Center Height Offset              Roll Center Height Offset           Roll Center Height Offset

Stock                                                            +13.4                                                       +9.8                                                    +6.4

Street                                                           +13.4                                                       +9.8                                                    +6.4

Sport                                                              +9.8                                                       +6.4                                                    +3.2

Race                                                               +6.4                                                        +3.2                                                     0.0

                                                                Max Rim Size                                  Max Rim Size - 1                             Max Rim Size - 2

Chassis Reinforcement      Anti-Dive / Anti-Squat Offset     Anti-Dive / Anti-Squat Offset      Anti-Dive / Anti-Squat Offset 

Stock                                                              -1.5                                                        -1.0                                                     -0.5

Street                                                             -1.5                                                        -1.0                                                     -0.5

Sport                                                              -1.0                                                        -0.5                                                      0.0

Race                                                               -0.5                                                        -0.5                                                      0.0

Dampers

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.

Dialing in dampers is a three step process:

  1. Set front bump according to cars minimum bump stiffness and front weight

  2. Set front rebound according to front bump and cars overall damping stiffness

  3. Set rear dampers according to front dampers and relation of front and rear spring rates 

First off adjust front bump according to cars minimum bump stiffness and front weight. Each body type has a minimum front bump required given in the table below. Generally older require higher bump stiffness than modern cars and race cars require lower bump stiffness than road cars.

 

Then increase front bump by 0.1 for each 200lb of front weight. Note that also front aero accounts for the cars front weight:

 

Front Weight = Weight * Front Weight Distribution + Front Downforce 

Example: Modern street car with 2200lb, 64% wd, 200lb front downforce, 4.4 Min. Bump

Front Bump = 4.4 + (2200*0.64 + 200)/200 * 0.1 = 4.4 + 0.8 = 5.2

Car Type                                  Min. Front Bump

Race Car                                            4.0-5.0            

Prototype Race Car                         4.0-4.5

GP Race Car                                     3.5-4.5

------------------------------------------------------------------------------------------------

Street Car                                         4.0-5.0

Sports Car                                        4.0-5.0

High Performance Car                   4.0-5.0

------------------------------------------------------------------------------------------------

Rally Sports Car                              4.0-5.0

------------------------------------------------------------------------------------------------

Off-road Car                                    3.0-5.0

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

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. 

That means rear rebound and rear bump are set to front rebound and front bump plus an offset according to front and rear spring rate difference.

Front-Rear Spring Rate      Rear Rebound Offset      Rear Bump Offset

Difference                                                      

<-10%                                                    +0.4                                   +0.2

<-5%                                                      +0.2                                   +0.1

-5%-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: RWD car with front spring rate 80%, rear spring rate is 50%

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

Rear rebound should be 0.3 lower than front rebound

Rear bump should be 0.2 lower than front bump

Prototype Race Cars

Prototype race cars require additional stiffening of rear dampers to stabilize the car due to higher forces on the chassis during cornering.

Car Type                                Rear Rebound Offset      Rear Bump Offset      

Prototype Race Car                             +3.5                                   +3.5   

GP Race Cars

 

GP race cars require additional stiffening of front dampers to stabilize the car on corner entry due to higher forces on the chassis during corner entry

Car Type                                Front Rebound Offset      Front Bump Offset      

GP Race Car                                          +3.5                                   +3.5   

Modern Cars with High Torque Engine Swaps  New 

 

Modern cars (built 1980 or later) that use a high torque engine swap (ex. 3.7L V6) require higher front damping depending on installed chassis reinforcement upgrade for best handling.

Chassis Reinforcement        Front Damper Offset

Stock                                                       +1.5

Street                                                      +1.5

Sport                                                       +1.0

Race                                                        +0.5

High Torque Vintage Cars  New 

Vintage cars (cars built before 1980) that have an engine with high stock torque (>=250lb/ft) or that use a high torque engine swap (ex. 3.7L V6) require higher rear damping depending on installed chassis reinforcement upgrade for best handling. 

Chassis Reinforcement       Rear Damper Offset

Stock                                                       +1.5

Street                                                      +1.5

Sport                                                       +1.0

Race                                                        +0.5

Relevant Car Upgrades

When decreasing weight bump might need to be decreased and rebound need to be increased to compensate for reduced 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

Brakes

Brake tuning in Forza depends solely on the type of car. Generally speaking race cars require more braking force on the rear and higher brake pressure than road cars and off-road cars require more braking force on the front and lower tire pressure than road cars.

Car Type                          Brake Distribution        Brake Pressure

Race Car                                        44%                                145%

Prototype Race Car                     44%                                145%

GP Race Car                                  44%                                145%

---------------------------------------------------------------------------------------------

Street Car                                      48%                                125%    

Sports Car                                     48%                                125%    

High Performance Car                44%                                145%

---------------------------------------------------------------------------------------------

Rally Sports Car                            52%                                125%    

---------------------------------------------------------------------------------------------

Off-road Car                                 52%                                115%

Differential

Differential

Differential is for fine tuning corner entry and exit behaviour. Also a good ratio between accel and decel 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. Also off-road cars require lower differential settings than road cars.

 

RWD Cars

68/35 is good middle ground for road 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).

70/34 is good middle ground for high performance cars, race cars and race trucks, increase accel and/or decrease decel for cars with more rigid chassis/suspension (e.g. modern race cars), decrease accel and/or increase decel for cars with more flexible chasssis/suspension (e.g. older race cars).

96/0 is good middle ground for prototype race cars, increase accel for modern protoype race cars, decrease accel for older prototype race cars with more flexible chasssis/suspension.

50/0 is good middle ground for GP race cars, increase accel for modern GP race cars, decrease accel for older GP race cars with more flexible chassis/suspension.

38/4 is good middle ground for modern rally sports cars, increase decel for older rally sports cars with more flexible chassis/suspension.

38/5 is good middle ground for modern off-road cars, decrease accel and/or increase decel for older off-road cars with more flexible chassis/suspension.

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.

Car Type                                Accel               Decel

Race Car                                 68-72%            34-35%

Prototype Race Car               94-98%               0%

GP Race Car                            44-52%               0%

-----------------------------------------------------------------------

Street Car                               64-68%            34-36%

Sports Car                              64-68%            34-36%

High Performance Car           70%                  34%

-----------------------------------------------------------------------

Rally Sports Car                        38%                 4-5%

-----------------------------------------------------------------------

Off-road Car                           36-38%              5-6%

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

Open Wheel Cars

Open wheel cars require lower accel and a generally complete open diff on braking to support those cars that have usually very wide wheel bases with cornering.

                                                            Accel Offset          Decel 

Open Wheel Car1                                    -24%                     0%              

except GP race cars

FWD Cars

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

Front Accel:  RWD Accel - 20%

Front Decel:       0%

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%

Cars without Race Weight Reduction  New 

For cars that are not equipped with full race weight reduction require higher accel and lower decel depending on installed weight reduction upgrade for best handling.

Weight Reduction           Accel Offset      Decel Offset 

Stock                                        +36%                      -30%

Street                                       +24%                      -20%

Sport                                        +12%                      -10%

Gearing

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. If the car uses a custom race gearbox the gearing is scaled to the cars stock power.

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

Cars with Standard Forza gearbox and 6-speed sport gearbox

For cars with a standard Forza race gearbox, a 6-speed sport gearbox and a stock final drive > 4.00 the gearbox is scaled to a reference final drive of 4.25.

To get the required final drive 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 final drive).

Example: RWD car, 325hp, stock final drive 4.21
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 5-speed sport gearbox

 

Cars with a Standard Forza 6-speed race gearbox, a 5-speed sport gearbox and a stock final drive of sport transmission > 4.00 the sport gearbox is scaled to a reference final drive of 4.00.

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

 

Cars with a Standard Forza 6-speed race gearbox and a 3- or 4-speed sport gearbox use a higher reference final drive for sport transmission.

For cars with a Standard Forza gearbox, a 4-speed sport gearbox and a stock final drive of sport transmission > 4.00 the sport gearbox is scaled to a reference final drive of 4.75.

For cars with a Standard Forza gearbox, a 3-speed sport gearbox and a stock final drive of sport transmission > 4.00 the sport gearbox is scaled to a reference final drive of 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 6-speed race gearbox and a stock final drive <= 3.00.

 

For cars with a Standard Forza 6-speed race gearbox and 5-, 4- or 3- speed sport gearbox and a stock final drive for race transmission <= 3.25 the race gearbox is scaled to a reference final drive of 3.25.

For cars with a Standard Forza 6-speed race gearbox and a 6-speed sport gearbox and a stock final drive for sport transmission <= 3.25 the sport gearbox is scaled to a reference final drive of 3.25.

For cars with a Standard Forza 6-speed race gearbox and a 5-speed sport gearbox and a stock final drive for sport transmission <= 3.25 the sport gearbox is scaled to a reference final drive of 3.00.

For cars with a Standard Forza 6-speed race gearbox and a 4-speed sport gearbox and a stock final drive for sport transmission <= 3.25 the sport gearbox is scaled to a reference final drive of 3.75.

For cars with a Standard Forza 6-speed race gearbox and a 3-speed sport gearbox and a stock final drive for sport transmission <= 3.25 the sport gearbox is scaled to a reference final drive of 3.50.

High Power Cars with Standard Forza gearbox

Cars with Standard Forza gearbox 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 gearbox 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 the gearbox is scaled to the cars stock final drive.

To get the required final drive 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.

Example: RWD car, 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

Cars with High or Low Torque Engine Swaps  New 

 

Cars  that use a high torque engine swap (ex. 3.7L V6) or a low torque engine swap (ex. 1.3L I4) require different final drive and gear ratio tuning for best handling.

Engine Swap           Final Drive Offset        Gear Ratio Offset

High Torque                         +1.0                                  -0.2

Low Torque                           -1.0                                 +0.2

Race Cars with Custom Gearbox  Changed 

Race cars with a custom gearbox generally require a final drive offset of 0.25 for best handling, i.e. the stock final drive must be increased by 0.25 when using stock power.

Race cars with a custom gearbox that don't offer any engine upgrades generally require a final drive offset of -0.75 for best handling, i.e. the stock final drive must be decreased by 0.75.

Race Car                             Final Drive Offset 

Engine Upgrades                         +0.25              

No Engine Upgrades                    -0.75              

Relevant Car Upgrades

Increasing or decreasing power via engine upgrades requires to adjust final drive to adjust the gearbox to the changed power band.

Also when performing a drivetrain swap on cars with a custom gearbox requires to adjust the final drive since cars with drivetrain swaps will always automatically be equipped with a Standard Forza gearbox which is scaled to a reference power of 400hp instead of the cars stock power in case of the cars custom gearbox (see above). 

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

Aero

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: front max / rear max

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

  • FWD/AWD (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) or maximum/minimum downforce levels (FWD/AWD) 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

Low Power Cars with Standard Forza Race Aero Kit

Cars with a standard Forza race aero kit and with very low power (<=200 hp) 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 Extreme Power

Cars that have extreme power (>=800 hp) require extra downforce 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=152 --> 100 (maximum downforce), Rear: (75*1.5)+2=114.5 --> 115

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.

Next - Grip and Speed Tuning

bottom of page