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Handling modifications guide

Created: 5.12.2019
Updated last: 5.1.2020


Prologue

This guide will give you rough guidelines on how to add certain types of modifications into the game. Please do follow these guidelines to ensure a steadily balanced vehicle system across the vehicle library.

All these values are guidelines, and they should not be stuck to religiously as all handlings respond differently. Use common sense and make sure cars handle in a reasonable way and that they are not under or overpowered.

REMEMBER: Everything is a trade-off when you upgrade a vehicle! When you make one thing better, other one gets worse!



1. Chassis

Chassis modifications have two major things they do: improve the actual physical handling of the vehicle, and reduce tolerances or movement within the chassis and suspension. Here´s a swift breakdown of some modifications.

Shocks, springs, coilovers
There is four categories of shocks, springs, coilovers that we use in RPP to make the handlings.  These categories are tied to their pricing point, and thus it´s easy to identify quality and cheap suspension components
OEM (stock suspension)
Refer to the vehicle handling guide
Budget
Very low priced and off-brand products (0-500 for shocks). These generally don´t ride well and only give out visual enhancements of lowering your car.
ALWAYS set budget shocks to have a very low dampening rate! 0.04-0.07 will do the trick.
Street & Track
Brand products like BC Racing, Stance Suspension, KW, Driftworks etc. These usually provide a good mix of comfort & handling. They increase driveability and handling of the car, but they don´t match up with high end racing suspension.
Suspension dampening shall be set to this margin: 0.08 - 0.11
Suspension force shall be added by +0.13 to the existing value, but not higher than 0.9 suspension stiffness.
Traction multiplier shall be raised by +0.13
Racing/Rally/Offroad
These are specificly made to offer high performance in a specific genre of driving. These products are EXPENSIVE. If someone uses a cheaper variant of a specificly made component, DO NOT make the handlings as good!
Racing/track
Suspension dampening shall be set to his margin: 0.07-0.09
Suspension force shall be set to this margin: 0.85-0.95
Centre of gravity can be lowered from the original value to margin of -0.05 to -0.25 depending on build level and supporting mods.
Traction multiplier shall be raised by +0.25
Traction balance shall be set to 0.5 or if the player RP´s changes, to his liking.
Offroad
Dampening shall be set high to absorb bumps
Suspension height shall be set high.
Suspension force anywhere between 0.6 to 0.75
Centre of mass shall be raised up +0.03 to +0.1 depending on height change.
Rally/rallycross
This is a mix of track & offroad suspension.
Suspension stiffness at 0.69 - 0.79
Centre of mass shal be raised up +0.02 to +0.04
Car MUST have very much body roll.
Setup changes
Changing solely the shocks (not coilovers) reduce or increase the damping of the vehicle. Usually higher quality shocks increase the damping by 0.04 to 0.06 units
For advanced users, damping rates can be changed to find certain handling charasteristics. This same applies to spring rates. Here´s some general guidelines for that:
Front end shocks
Reduce bump & rebound rate on shocks -> Car becomes more oversteery and more weight is transfered to the front
Increase bump & rebound rate on shocks -> Car becomes more undesrsteery as less weight is transfered to the front
Rear end shocks
VICE VERSA to front end shocks!
Remember that LOWERING THE CAR STIFFENS the suspension!


Rose joint swaps, suspension arms, steering, bracing, rollcages
This is a quick overview of the most common suspension upgrades that you may encounter in the requests.
Suspension arms & Rose links
These usually just offer more stiffness and adjustability, and they come with rose joints that reduces slack in the suspension components, replacing the traditional ball joints.
Added +0.02 suspension force
Lowers centre of gravity by -0.02
Increases traction multiplier by +0.03
Reduces body roll in general
Toe out adjustments
This mean changing the toe setting to a more outwards state. Adds +3 steering lock.
Steering rack spacers
This raises the steering ability by 10 degrees, but no more than 45 degrees in total.
Wisefab & Knuckle changes
This enables the cars to have 55-60 degrees of steering lock.
Chassis bracing
Correctly done chassis bracing makes the car more stiffer and reduces body roll
This should add weight! Remember to put additional weight in the P/W ratio calculator before you make the handling itself!
Depending on how extensive the job is, this should add +0.02 to +0.04 suspension stiffness
Depending on how extensive the job is, this should lower the centre of gravity by -0.02 to -0.03
Rollcages
Correctly done rollcage makes the car more stiffer and reduces body roll
This should add weight! Remember to put additional weight in the P/W ratio calculator before you make the handling itself!
Refer to the guidelines in the chassis bracing paragraph.
Drag car specific suspension changes: Ladder bars, 4-links etc.
In order for a drag car to gain it´s full potential, it requires a sophisticated rear-end setup to generate the required grip on launch. Ladder bars are an easy way to generate some grip, but a full 4-link setup is superior to it. There is no specific value settings for these, but keep in mind that these GREATLY affect the car´s rear end grip on drag cars. No car with stock suspension configuration can launch hard.


2. Rear end gears,transmission & diff

Rear end gears
A player can lower their car´s inertia by changing higher rear-end´s gearing. This means that they will gain a considerable acceleration gain, but they´ll loose out in the top speed. This works the other way around too, Higher top speeds can be achieved with lower gearing, but acceleration is greatly impacted.
We can not accurately simulate real life gearing in a car, thus we´ve come up with a system that affects both the car´s top speed and acceleration
Two values will be affected by this formula. Inertia and top speed.
Formula: Inertia * 3.5 = Affection in top speed in km/h
Example:
I want my car to have 5 less inertia, and it has a top speed of 270kmh.
5*4 = 20kmh -> My car´s new top speed is 250kmh, but it reaches it quicker.
This means that in order for me to REDUCE inertia, I will REDUCE the actual top speed by 18kmh. Not the top speed value, the actual IG top speed.
Rule of thumb: Higher inertia requires higher top speed. Lower inertia requires lower top speed.
As this can´t be set to any certain chart, you must just ask the player what feels the best for him.
DO NOT GO under 20 inertia with normal car requests!
DO NOT GO over 100 inertia with normal car requests!
To get a general idea, 3.1 is a low gear ratio and 4.3 is a very high gear ratio. Please search the internet to find more info on this matter
LSD´s & Welded diffs
LSD´s on RWD cars usually help on putting the power down to the ground bit better, but the more locking the diff has, the harder the car is to corner.
Traction multiplier shall be increased by +0.02 with an LSD install
Traction bias can get an additional +0.05 to it with an LSD
LSD´S on FWD cars usually help cornering a lot.
Traction multiplier shall be increased by +0.02
Car should corner better. Do the changes with traction bias.
Welded diffs make mad slides.
Transmissions
Transmissions can take off some time of acceleration. I´ve listed two types of transmission upgrades:
Sequential
-2 on inertia
Automatic / other drag transmission
-5 on inertia
3. Power & Weight

Power & weight shall only be affected via the P/W calculator script! When discussing a mod request, please discuss how the weight & power is affected. Remember that BIG ENGINES add weight and vice versa! Google can be used to determine a weight for a certain part.

NOTE: When big power is added (over 400hp), lower the traction multiplier accordingly before proper suspension & tire setup is installed!



4. Tires

Junker & cheap tires (NO TO DRIFT TIRES!!!)
These can be used to lower grip levels.
Traction multiplier 0.5-0.6
Normal road car tires
Stock value on the vehlib handling
Improved road car tires
Adds +0.03 traction multiplier
Semi Slicks
Adds +0.13 traction multiplier, but not higher than 0.9 in total
Semi slicks are made for lattitudal grip. THEY DO NOT offer LAUNCH traction! Make sure the rear wheels have some spin, and the car is slightly more tail-happier after the modification!
Semi slicks should NOT stick the car to the ground.
Track racing slicks
These offer LATTITUDAL grip, so they are good in corners!
Adds +0.2 traction multiplier, but not higher than 1.0 in total
Traction balance shall be set to 0.5 or higher to introduce some sliding to the rear end.
THESE ARE FOR RACING VEHICLES ONLY. If someone puts slicks on a road car, set the traction multiplier to 0.5 and traction bias to 0.55. Racing slicks require a clean surface and a high temperature to work.
Drag radials & slicks
Any type of a drag tire should increase longitudinal grip and DECREASE cornering ability of the car. Drag tires are made to wrinkle and provide forwards traction.
If a big drag slick is added to a car, the centre of mass shall be raised by +0.1 higher as drag slicks tend to make the car easier to topple over.
There´s no set value for the traction multiplier, but here´s few rules of thumb:
If the car does not have extensive rear suspension modifications done, and it´s trying to put down big power, leave some wheelspin in the rear tires.
ZERO wheelspin launches shall only be made for cars that have proper rear-end suspension to put that power in the ground!
Also, smaller drag slicks do slip! Only BIG drag tires are zero wheelspin!
Set the traction bias to 0.25 to 0.3 to reduce the turning ability of the vehicle.