Horizon 4 Tuning Guide
Part 2 - Road Tuning
This part explains how to setup cars in a way that they will work good for road and street racing.
This also serves a basis for off-road tuning which will be covered in part 3 so make sure to read this first before advancing to these topics.
Understanding Tuning Relevant Car Properties
As in Part 1 explained car type, body type and drive 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 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 Aero Brakes Diff
Car Type ✓ ✓
Body Type ✓ ✓ ✓ ✓ ✓
Drive Type ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓
Power ✓ ✓1 ✓1 ✓1
Weight ✓ ✓ ✓ ✓
Chassis Reinf. ✓ ✓
Tire Compound ✓
Tire Width ✓ ✓
Aero Kits ✓ ✓ ✓
1 only in special cases
Tires
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 for FR (front engine RWD) cars 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 Front Tire Pressure Rear Tire Pressure
(FR) (FR)
Stock 28.0 28.0
Street 28.0 28.0
Sport 28.5 28.5
Rally / Snow 28.5 28.5
Oldtimer Race 28.5 28.5
Rally Race 29.0 29.0
Race 29.0 29.0
Race Horizon 29.0 29.0
Drag 29.5 29.5
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 is Race compound (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: This method will provide peak tire performance starting 3th lap, the first two laps are needed to warm-up the tires.
AWD and FWD Cars
AWD and FWD cars require lower tire pressure on the front and higher tire pressure on the rear as compared to RWD cars to stabilize the car while turning.
Front Tire Pressure Offset Rear Tire Pressure Offset
AWD -1.0 +1.0
FWD -2.0 +2.0
Mid and Rear Engine Cars
Mid and rear engine cars require higher tire pressures on the front and lower tire pressures on the rear as compared to regular front engine cars.
Front Tire Pressure Offset Rear Tire Pressure Offset
Mid Engine +1.0 -1.0
Rear Engine +2.0 -2.0
Race Cars and High Performance Cars
Aside from tire compound, drivetrain and engine position 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
Race Truck +0.5
Prototype Race Car +0.5
Open Wheel Race Car +0.5
------------------------------------------------------------
Off-road Race Truck +0.5
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.
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.
Car Type Usual Camber Range
(FR Race Suspension)
Utility Car -3.0 to 0.0
Street Car -3.0 to 0.0
Sports Car -3.0 to 0.0
High Performance Car -2.5 to -1.0
Race Car -2.5 to -1.5
Race Truck -2.0 to 0.0
Prototype Race Car -2.0 to -1.0
Open Wheel Race Car -3.5 to -1.5
------------------------------------------------------------------------
Rally Car -2.5 to -0.5
Off-road Car -2.5 to -1.0
Off-road Truck -3.0 to -2.0
Open Wheel Off-road Car -3.0 to -1.0
Off-road Race Truck -2.5 to -2.0
The ranges given account for different body types within the car type.
Rally and off-road suspension generally require higher camber than race suspension. Simply reduce race suspension front camber by 1.0 and rear camber by 0.5 to get required camber for rally or off-road suspension.
Car Type Usual Camber Range
(FR Rally / Off-road Suspension)
Utility Car -4.0 to -0.5
Street Car -4.0 to -0.5
Sports Car -4.0 to -0.5
High Performance Car -3.5 to -1.5
Race Car -3.5 to -2.0
Race Truck -3.0 to -0.5
Prototype Race Car -3.0 to -1.5
Open Wheel Race Car -4.5 to -2.0
-----------------------------------------------------------------------------
Rally Car -3.5 to -1.0
Off-road Car -3.5 to -1.5
Off-road Truck -4.0 to -2.5
Open Wheel Off-road Car -4.0 to -1.5
Off-road Race Truck -3.0 to -0.5
The ranges given account for different body types within the car type.
AWD and FWD Cars
FWD cars require more front camber than RWD cars to compensate for more front body roll. AWD cars require more front and rear camber than RWD cars.
Front Camber Offset Rear Camber Offset
AWD -0.2 -0.2
FWD -0.4 0.0
Mid and Rear Engine Cars
Mid engine cars require higher front and rear camber and rear engine cars require higher rear camber than regular front engine cars.
Front Camber Offset Rear Camber Offset
Mid Engine -0.2 -0.2
Rear Engine 0.0 -0.4
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 road and off-road cars as I find this improves accelerating out of turns, i.e. reduces on-throttle understeer.
Car Type Rear Toe
Utility Car -0.3-0.0
Street Car -0.3-0.0
Sports Car -0.3-0.0
High Performance Car 0.0
Race Car 0.0
Race Truck 0.0
Prototype Race Car 0.0
Open Wheel Race Car 0.0
--------------------------------------------------------
Rally Car -0.3-0.0
Off-road Car -0.3-0.0
Off-road Truck -0.3-0.0
Open Wheel Off-road Car -0.3-0.0
Off-road Race Truck -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 when using race suspension heavy off-road cars like off-road trucks require low caster, road and race cars require medium caster and lighter rally or off-road cars like buggies require high caster.
Car Type Caster
(Race Suspension)
Utility Car 5.0
Street Car 5.0
Sports Car 5.0
High Performance Car 5.0
Race Car 5.0
Race Truck 5.0
Prototype Race Car 5.0
Open Wheel Race Car 5.0
--------------------------------------------------------------
Rally Car 5.0/6.5
Off-road Car 5.0
Off-road Truck 2.0/5.0
Open Wheel Off-road Car 6.5
Off-road Race Car 6.5
Off-road Race Truck 2.0/5.0
The ranges given account for different body types within the car type.
For most cars rally and off-road suspension require different caster settings due to different suspension geometry compared to race suspension. As a general rule of thumb road, race and rally cars require high caster, off-road cars and trucks require medium caster and off-road race cars and trucks require low caster.
Car Type Caster
(Rally / Off-road Suspension)
Utility Car 4.0-6.5
Street Car 4.0-6.5
Sports Car 6.5
High Performance Car 6.5
Race Car 6.5
Race Truck 5.0
Prototype Race Car 6.5
Open Wheel Race Car 6.5
---------------------------------------------------------------------
Rally Car 6.5
Off-road Car 4.0
Off-road Truck 2.0/4.0
Open Wheel Off-road Car 2.0
Off-road Race Truck 2.0
The ranges given account for different body types within the car type.
Note: For most cars the stock caster is already set to optimal value, so you don't need to change it usually.
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
(FR)
Utility Car 63-66% 1.00-2.95
Street Car 63-66% 0.98-1.50
Sports Car 61-65% 0.66-1.00
High Performance Car 40-46% 0.55-0.65
Race Car 35-62% 0.35-0.80
Race Truck 15% 0.35
Prototype Race Car 28-48% 0.25-0.35
Open Wheel Race Car 18% 0.35
----------------------------------------------------------------------------------------
Rally Car 61-65% 0.70-0.77
Off-road Car 61-65% 1.45-2.95
Off-road Truck 61-65% 1.55-3.00
Open Wheel Off-road Car 61-65% 1.05-1.15
Off-road Race Truck 61-65% 1.00-2.53
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.
Mid and Rear Engine Cars
Mid and rear engine cars require reverse setup of front and rear ARBs as compared to regular front engine cars.
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 Increase
Chassis Reinforcem. Street None
Chassis Reinforcem. Sport Decrease1
Chassis Reinforcem. Race Decrease2
1 Reduce ARB stiffness by 3%
2 Reduce ARB stiffness by 6%
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
(FR Race Suspension)
Utility Car 93-100% 57-80%
Street Car 93-100% 57-80%
Sports Car 87-98% 58-80%
High Performance Car 85-93% 63-84%
Race Car 83-93% 59-85%
Race Truck 80% 90%
Prototype Race Car 79-83% 70-89%
Open Wheel Race Car 66% 79%
------------------------------------------------------------------------------------------------
Rally Car 80-100% 57-80%
Off-road Car 94-100% 57-80%
Off-road Truck 94-100% 57-80%
Open Wheel Off-road Car 94-100% 57-80%
Off-road Race Truck 94-100% 57-80%
The ranges given account for different body types within the car type.
Example: RWD road car with 3000lbs @ 52% wd
front springs 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.
For rally suspension simply use half of the springs rates as compared to race suspension since rally suspension in general provides exactly half of the spring rate ranges as race suspension.
For cars with off-road suspension (these are all off-road cars with a stock adjustable suspension) suspension tuning works a little bit different than for race or rally suspension. Instead of using front and rear spring rates that are related to front and rear weight, front and rear springs must be related to available front and rear spring ranges. So a front spring rate of 39% means front springs must be set to 39% of the available front spring range with 0% would be the minimum allowed front spring rate and 100% the maximum allowed front spring rate.
The available front and rear spring range can be calculated by multiplying the cars weight with the (car specific) minimum and maximum front and rear spring rates.
Car Type Front Spring Rate Rear Spring Rate
(FR Off-road Suspension)
Off-road Car 39-40% 6-7%
Off-road Truck 39-40% 6-7%
Open Wheel Off-road Car 39-40% 6-7%
Off-road Race Truck 38-39% 6-7%
The ranges given account for different body types within the car type.
Example: RWD off-road buggy with stock adjustable suspension, 2200lbs, front springs min/max: 77.8/142.6, rear springs min/max: 95.1/142.6
front springs would be between:
77.8 + (142.6-77.8) * 39% = 103.1 and
77.8 + (142.6-77.8) * 40% = 103.7 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.
Mid and Rear Engine Cars
Mid and rear engine cars require reverse setup of front and rear springs as compared to regular front engine cars.
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.
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 (100-220/220-441) balanced downforce is achieved e.g. when both downforce sliders are set to minimum values (110/220) . The higher you go the more rear downforce is required to achieve balanced downforce, e.g. 165/358 or 198/441. 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 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 Bumper1 10lb
Street Front Bumper 10lb
Sport Front Bumper 40lb
Stock Rear Wing2 25lb
Street Rear Wing 25lb
Sport Rear Wing 70lb
Stock Rear Bumper1 25lb
Street Rear Bumper 25lb
Sport Rear Bumper 50lb
1 Some off-road cars and trucks don't have stock bumpers, so in this case there is no downforce applied
2 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
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
1 Reduce front spring rate by 2.75%
2 Reduce front spring rate by 5.5%
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
Utility Car 5.0-7.0
Street Car 5.0-7.0
Sports Car 5.0-7.0
Open Wheel Car 5.0-7.0
High Performance Car 4.0-5.0
Race Car 4.0-6.0
Race Truck 4.5
Prototype Race Car 3.5-4.5
Open Wheel Race Car 5.5
--------------------------------------------------------------------
Rally Car 5.0-7.0
Off-road Car 5.0-7.0
Off-road Truck 5.0-7.0
Open Wheel Off-road Car 5.0-7.0
Off-road Race Truck 5.0-7.0
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 Rebound Bump
(FR Race Suspension)
Utility Car 10.0-12.0 5.0-6.0
Street Car 10.5-12.5 4.5-5.5
Sports Car 10.5-12.5 4.5-5.5
High Performance Car 12.5-16.5 4.5-6.5
Race Car 14.5-16.0 5.0-6.0
Race Truck 18.0-18.5 7.5-8.0
Prototype Race Car 18.0-20.0 6.0-8.0
Open Wheel Race Car 13.0-14.0 15.5-16.5
Open Wheel Sports Car 6.5-11.5 6.5-11.5
Open Wheel Street Car 7.5-11.0 7.5-11.0
---------------------------------------------------------------------------
Rally Car 10.5-12.5 4.5-5.5
Off-road Car 10.0-11.5 4.0-6.0
Off-road Truck 10.0-11.5 5.5-6.5
Open Wheel Off-road Car 9.5-12.5 9.5-12.5
Off-road Race Truck 8.0-10.5 8.0-10.5
The ranges given account for different body types within the car type and weight ranges.
When using rally or off-road suspension damping needs to be scaled down due to the lower damping range as compared to race suspension.
Car Type Rebound Bump
(FR Rally / Off-road Suspension)
Utility Car 6.5-8.5 1.5-2.5
Street Car 7.0-9.0 1.0-2.0
Sports Car 7.0-9.0 1.0-2.0
High Performance Car 9.0-9.5 1.5-3.0
Race Car 7.5-9.0 2.0-3.0
Race Truck 10.0 6.0-8.0
Prototype Race Car 7.5-9.5 4.0-6.0
Open Wheel Race Car 6.0-7.0 8.5-9.5
Open Wheel Sports Car 3.0-8.0 3.0-8.0
Open Wheel Street Car 4.0-7.5 4.0-7.5
---------------------------------------------------------------------------
Rally Car 7.0-9.0 1.0-2.0
Off-road Car 6.5-8-0 1.5-2.5
Off-road Truck 6.5-8.0 2.0-3.0
Open Wheel Off-road Car 6.0-9.0 6.0-9.0
Off-road Race Truck 4.5-7.0 4.5-7.0
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.
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
Prototype Race Cars, Open Wheel Cars and Off-Road Race Trucks
Prototype race cars, open wheel cars and off-road race trucks require stiffer rear damping than other cars.
Car Type Rear Damping Offset
Prototype Race Car +3.5
Open Wheel Race Car +3.5
Open Wheel Sports Car +2.5
Open Wheel Street Car +2.5
---------------------------------------------------------------------------
Open Wheel Off-road Sports Car +2.5
Open Wheel Off-road Car +1.5
Off-road Race Truck +0.5
AWD and FWD Cars
AWD and FWD cars require higher front dampers to stabilize the car on corner entry.
Front Rebound Offset Rear Rebound Offset Front Bump Offset Rear Bump Offset
AWD +1.5 0.0 +1.5 0.0
FWD +2.5 0.0 +2.5 0.0
Mid and Rear Engine Cars
Mid engine cars require reverse setup of front and rear rebound as compared to regular front engine cars. They also require a stiffer rear rebound and front bump than regular front engine cars.
Rear engine cars require reverse setup of front and rear rebound and bump as compared to regular front engine cars. They also require a stiffer rear rebound and rear bump than regular front engine cars.
Front Rebound Offset Rear Rebound Offset Front Bump Offset Rear Bump Offset
Mid Engine 0.0 +1.5 +1.5 0.0
Rear Engine 0.0 +2.5 0.0 +2.5
Relevant Car Upgrades
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 in Forza depends on the type of car and the type of drivetrain. 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
(FR Race Suspension)
Utility Car 50% 120%
Street Car 52% 125%
Sports Car 52% 125%
High Performance Car 54% 135%
Race Car 56% 145%
Race Truck 56% 145%
Prototype Race Car 56% 145%
Open Wheel Race Car 56% 145%
Open Wheel Sports Car 54% 135%
Open Wheel Street Car 54% 135%
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Rally Car 52% 125%
Off-road Car 48% 115%
Off-road Truck 52% 135%
Open Wheel Off-road Car 52% 135%
Off-road Race Truck 52% 135%
Rally or off-road suspension generally require more braking force on the front as compared to race suspension.
Car Type Brake Distribution Brake Pressure
(FR Rally / Off-road Suspension)
Utility Car 50% 120%
Street Car 48% 125%
Sports Car 48% 125%
High Performance Car 50% 135%
Race Car 52% 145%
Race Truck 52% 145%
Prototype Race Car 52% 145%
Open Wheel Race Car 52% 145%
Open Wheel Sports Car 50% 135%
Open Wheel Street Car 50% 135%
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Rally Car 48% 125%
Off-road Car 48% 115%
Off-road Truck 52% 135%
Open Wheel Off-road Car 52% 135%
Off-road Race Truck 52% 135%
AWD and FWD Cars
AWD and FWD cars require more braking force on the front and a lower brake pressure than RWD cars.
Brake Distribution Offset Brake Pressure Offset
AWD +2% -5%
FWD +4% -10%
Mid and Rear Engine Cars
Mid and rear engine cars require higher braking force on the the rear and a higher brake pressure than regular front engine cars.
Brake Distribution Offset Brake Pressure Offset
Mid Engine -2% +5%
Rear Engine -4% +10%
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 road cars. Also off-road cars require lower differential settings than road cars.
RWD Cars
74/75 is good middle ground for modern 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).
44/45 is good middle ground for modern off-road cars, decrease accel and/or increase decel for older off-road cars with more flexible chasssis/suspension.
45/0 is good middle ground for modern open wheel cars, decrease accel for older open wheel cars with more flexible chasssis/suspension.
36/0 is good middle ground for open wheel race cars
Car Type Accel Decel
(FR Race Suspension)
Utility Car 73-74% 75-76%
Street Car 73-74% 75-76%
Sports Car 73-74% 75-76%
High Performance Car 75% 74%
Race Car 75-76% 73-74%
Race Truck 76% 74%
Prototype Race Car 87-89% 0%
Open Wheel Race Car 46% 0%
Open Wheel Sports Car 53-55% 0%
Open Wheel Street Car 55% 0%
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Rally Car 73-74% 75-76%
Off-road Car 43-44% 45-46%
Off-road Truck 43-44% 45-46%
Open Wheel Off-road Car 55% 0%
Off-road Race Truck 43-44% 45-46%
The ranges given account for different body types within the car type.
Rally or off-road suspension generally require 10% lower diff settings as compared to race suspension.
Car Type Accel Decel
(FR Rally / Off-road Suspension)
Utility Car 63-64% 65-66%
Street Car 63-64% 65-66%
Sports Car 63-64% 65-66%
High Performance Car 65% 64%
Race Car 65-66% 63-64%
Race Truck 66% 64%
Prototype Race Car 77-79% 0%
Open Wheel Race Car 36% 0%
Open Wheel Sports Car 43-45% 0%
Open Wheel Street Car 45% 0%
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Rally Car 63-64% 65-66%
Off-road Car 33-34% 35-36%
Off-road Truck 33-34% 35-36%
Open Wheel Off-road Car 45% 0%
Off-road Race Truck 33-34% 35-36%
The ranges given account for different body types within the car type.
FWD Cars
49/0 is good middle ground for modern road cars, decrease accel for older cars with more flexible chassis/suspension
Car Type Accel Decel
(FF Race Suspension)
Street Car 48-49% 0%
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Rally Car 48-49% 0%
The ranges given are for the different body types within the car type.
As with RWD cars using rally or off-road suspension generally require 10% lower diff settings as compared to race suspension.
Car Type Accel Decel
(FF Rally / Off-road Suspension)
Street Car 38-39% 0%
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Rally Car 38-39% 0%
The ranges given are for the 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%
Mid and Rear Engine Cars
Mid and rear engine cars require lower accel and higher decel as compared to regular front engine cars.
Accel Offset Decel Offset
Mid Engine -12% +20%
Rear Engine -24% +40%
Gearing
For general road tuning only adjustment of the final drive is required. Tuning single gears ratios is only required when tuning for specific seasons or weather conditions.
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: Car with 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 < 4.00.
For cars with a Standard Forza 6-speed race gearbox and 5-, 4- or 3- speed sport gearbox a stock final drive for race transmission < 4.00 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 < 4.00 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 < 4.00 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 < 4.00 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 < 4.00 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: Car with 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
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 tuning in Horizon is relatively easy as it depends only on the drivetrain and the installed aero kit.
There are two types of race aero kits:
-
Standard Forza race aero kit: adjustable aero kit with front downforce range 110-220 and rear downforce range 220-441
-
Custom race aero kit (any other adjustable aero kit)
Cars with Standard Forza Race Aero Kit
For cars with a standard Forza Race Aero Kit setup downforce levels as follows:
-
RWD: front min / rear max
-
FWD / AWD: front max / rear min
Cars with Custom Race Aero Kit
Cars with a custom Race Aero Kit and stock drivetrain always require maximum front and rear rear aero:
-
RWD: front max / rear max
-
FWD / AWD: front max / rear max
Cars with Custom Race Aero Kit and Drivetrain Swaps
For cars with a custom Race Aero Kit and an installed drivetrain swap setup downforce levels as follows:
-
RWD: front min / rear max
-
FWD / AWD: front max / rear min
High Power Cars
Cars with very high power (>= 800hp for production cars, >= 1.5* stock power for race cars) always require maximum front and rear rear aero regardless of drivetrain and installed aero kit.