You can edit the Helper Base mod to try out modding, it contains the default data to start editing and a few examples of how to change textures and add logos and radio sounds (delete all the included image and sound files before playing). It's located in Formula TOP_Data/StreamingAssets/Mods (default path is C:\Program Files (x86)\Steam\steamapps\common\Formula TOP\Formula TOP_Data\StreamingAssets\Mods)

drivers.json is used for all single player game modes. All the other .json files are only used for career mode.

Don't change references. OrderNumber dictates the default order for cars and teams.
PrioritySignTargetReferences affects who a team will sign on the first season, no effect after that.
TeamAssociations for a driver make those teams prefer the driver more, can be used to simulate driver academies for junior drivers for example

Values for different fields should be between:

• Car stats: 4-10
  
• Team principal skill: 50-100
  
• Driver skill: 50-100
  
• Driver dirtiness: 0-5
  
• Team budget: 1-5
  
• Team development: 1-5
  
• Car potential Modifier -1 - 1
  
• Tyre wear: 1-3 (bigger is better)
  
• Reliability: 1-3
  
• Engine manufacturer consistency: 1-3
  
• Engine deal type: "C" for customer or "MW" for manufacturer works

For driverTextures, liveryTextures, liveryWingsTextures and logoSmall files from 1.png to 20.png are unique for each driver and they are used for Quick Race and Championship. Files from t1.png to t10.png are used for Career and they are per team. For logoLarge only t1.png to t10.png is used. For helmetTextures only 1.png to 20.png is used.

Radio sounds can be .wav or .mp3 files. Maximum file length is 10 seconds. Multiple options can be provided by ending the filename with _1, _2, _3 and so on. Filenames are:

• FastestLap
  
• FinalLap
  
• DriverRetired
  
• DriverEngineFailure
  
• WeatherChange
  
• PitConsiderLight
  
• PitConsiderHard
  
• PitNow

Drivers' skill change according to their age and their performance on track. From age 16 to 18 the development is most rapid. Drivers aged 14 and younger do not develop at all so you can add a driver that is for example 10 years old at the start of the career and they will still have the same skill rating you set in the mod at age 14. The higher the skill at a young age, the more likely it is the driver will reach a very high skill later on. You can check appropriate skill values for different ages in the Helper Base mod.

NOTE: You must have at least 19 drivers under the age 30 throughout the 10 year career so always have plenty of young extra drivers.

Since version R109 you can add a settings.json file to the mod folder to adjust the following settings:

• "startYear" - starting year in career mode (note driver ages are calculated by comparing their birth year to current year)
  
• "playerTeamReference" - starting team for player in career mode
  
• "pointsForPos" points structure in both championship mode and career mode
  
• "pointsForFastest" points awarded for fastest lap in both championship mode and career mode

Example:

To make edits yourself, create a local version of the mod that isn't tied to Steam Workshop:

• Copy the mod folder from your workshop directory, the default path is
  C:\Program Files (x86)\Steam\steamapps\workshop\content\1969650\
  
• Paste the mod folder to your Formula TOP_Data/StreamingAssets/Mods directory, the default path is C:\Program Files (x86)\Steam\steamapps\common\Formula TOP\Formula TOP_Data\StreamingAssets\Mods
  
• Change the folder name from the workshop mod id to what you'd like to be the mod's name

If you'd like to share a mod in the Workshop, add a .txt description file that has the same name as the mod folder to your Mods folder. So for example if you have a mod Formula TOP_Data/StreamingAssets/Mods/MyMod you should add the file
Formula TOP_Data/StreamingAssets/Mods/MyMod.txt and inside the file add the description for your mod. You can also add a .jpg preview image with the same name, so for example
Formula TOP_Data/StreamingAssets/Mods/MyMod.jpg.

Then in the game's settings menu when selecting the mod an upload button should appear. You can edit some mod details in the Workshop after uploading like adding more images. You can update your mod by selecting upload again after making changes.