What Jbeam files do and where to find them

Jbeam is the text-based file format that BeamNG Drive uses to define how a car behaves — its weight, suspension stiffness, engine power, tire grip, and hundreds of other physical properties. When you edit a Jbeam file, you are changing the numbers that control how a vehicle handles, accelerates, and crashes. The game reads these files when it loads a car, so changing them changes what you drive.

Jbeam files live in your BeamNG installation folder under vehicles/, organized by car name. A single car usually has multiple Jbeam files: one for the chassis, one for the engine, one for the suspension, and so on. They are plain text files you can open in any text editor — Notepad, VS Code, or Sublime Text all work. You do not need special software.

The safest place to find edited Jbeam cars is the official BeamNG forums and the community repository at BeamNG.drive Community Mods. These sites host cars that other players have already modified and tested. If you want to edit a car yourself, start by making a copy of an existing vehicle folder so you have a backup of the original.

Key Takeaways

  • Jbeam files are plain-text documents that control every physical property of a car, and you can edit them with any text editor like Notepad or VS Code.
  • Always make a backup copy of the original vehicle folder before you edit anything, so you can revert if something breaks.
  • Common edits include changing engine power in the engine Jbeam file, adjusting suspension stiffness in the suspension file, and modifying tire grip in the tire file.
  • BeamNG will show you an error message in the game console if your Jbeam syntax is wrong — look for red text that tells you which line has the problem.
  • Test your changes in a straightforward scenario first, like a flat road or a slow crash, before taking your edited car into complex situations.

Opening and reading a Jbeam file

Navigate to your BeamNG installation folder. On Windows, this is usually C:\Users\[YourUsername]\AppData\Local\BeamNG.drive or wherever you installed the game. On Mac or Linux, look in your home folder under .local/share/BeamNG.drive. Inside, open the vehicles folder and find the car you want to edit.

Right-click the vehicle folder, select "Copy", and paste it into the same vehicles folder. Rename the copy something like carname_custom. This copy is now your working version. Open the main Jbeam file (usually named after the car) with a text editor. You will see a structure of nested curly braces and key-value pairs — this is JSON format, which BeamNG uses for Jbeam files.

The file will look overwhelming at first. Scroll through and look for familiar words: "power" for engine output, "stiffness" for suspension springs, "damping" for shock absorbers, "friction" for tire grip. These are the properties you can change. Each one has a number next to it. That number is what you edit.

Making your first edit: engine power

Engine power is one of the safest first edits because the change is obvious and it will not break the file if you get the syntax slightly wrong. Search for "power" in your text editor using Ctrl+F (or Cmd+F on Mac). You will find a line that looks like "power": 150000, or similar. That number is in watts. A typical car engine is 100,000 to 200,000 watts.

Change the number to something higher — try doubling it to "power": 300000, — and save the file. Launch BeamNG, load your custom car, and drive it. You should feel the difference when ready. If the game crashes or shows an error, close the game, undo your change, and try again.

The most common mistake is deleting the comma at the end of the line. Jbeam files require commas between properties. If you see "power": 300000 without a comma after the number, add it back: "power": 300000,. The error message in the BeamNG console will usually tell you which line has the problem.

Adjusting suspension and handling

Suspension changes feel more dramatic than engine changes because they affect how the car turns and bounces. Search for "stiffness" to find spring rates. Higher numbers make the suspension stiffer and the car sit lower. Lower numbers make it bouncier. A typical value is 50000 to 100000. Try changing it by 20 percent at a time — if it is 80000, try 96000 or 64000 — and test in the game.

Search for "damping" to find shock absorber settings. These control how quickly the suspension stops bouncing after a bump. Too low and the car will oscillate wildly. Too high and it will feel stiff and disconnected from the road. Start with small changes: if the value is 5000, try 5500 or 4500.

For tire grip, search for "friction" or "frictionCoef". This number controls how much traction the tires have. Higher values make the car grip better in corners and accelerate faster. Lower values make it slide more easily. Typical values are 0.8 to 1.2. Changes here are subtle but noticeable in tight corners.

Testing your changes safely

Do not test a heavily modified car on a complex track or in traffic first. Instead, load a straightforward scenario: the flat test track, a straight road, or a slow-speed parking lot. Drive normally and feel how the car responds. Then try the specific thing you changed — accelerate hard if you modified engine power, take a sharp corner if you changed suspension, brake suddenly if you adjusted tire friction.

If something feels broken — the car flips easily, the engine will not start, or the steering is backwards — close the game without saving, go back to your text editor, and undo the change. Jbeam edits take effect when you load the car, so you do not need to restart the game between attempts.

Keep a notebook or text file of what you changed and how it felt. Write down things like "increased power by 50 percent, car now spins out in second gear" or "lowered suspension stiffness by 30 percent, car feels more planted in corners". This record helps you find the sweet spot and avoid repeating failed experiments.

Common mistakes and how to fix them

The most frequent error is a syntax mistake: a missing comma, a mismatched brace, or a typo in a property name. When you save and load the car in BeamNG, the game will not load it and will show an error in the console. Press F11 in the game to open the console and look for red text. It will usually say something like "Error on line 247: expected comma" or "Unknown property: 'powwer'". Go back to that line in your editor and fix it.

Another common problem is changing a value to something physically impossible. If you set engine power to 10,000,000 watts, the car will accelerate so fast it becomes uncontrollable. If you set suspension stiffness to 1, the car will sink through the ground. Start with small changes — 10 to 20 percent — and work your way up. You can always make it more extreme later.

If you accidentally delete a whole section of the file, you can undo in your text editor (Ctrl+Z) to get it back. If you have already closed the editor, go back to your backup copy of the original vehicle folder and copy the original file again. This is why making a backup at the start is important.

Where to learn more about Jbeam structure

The official BeamNG documentation has a Jbeam reference that explains what each property does and what values are reasonable. You can find it on the BeamNG wiki. The community forums also have threads where players share their edits and explain their reasoning — reading these teaches you what changes produce what effects.

If you want to make more advanced edits — like changing gear ratios, adjusting brake bias, or modifying aerodynamics — the same process applies: find the property name, understand what the number controls, make a small change, and test. The learning curve is gentle because you can always undo.

Frequently Asked Questions

Can I break BeamNG by editing a Jbeam file wrong?

No. A broken Jbeam file will straightforward fail to load, and the game will show an error. You can always delete the broken file and copy the original again. The worst that happens is the car will not appear in your garage until you fix it.

Do I need to restart BeamNG after I edit a Jbeam file?

No. Close the game, edit the file, save it, and launch the game again. The changes will be there when you load the car. You do not need to reinstall or do anything special.

Can I edit multiple properties in one file at once?

Yes. You can change engine power, suspension stiffness, and tire friction all in the same file before you test. But if something goes wrong, it is harder to know which change caused the problem. Start with one change per test session until you understand how each property affects the car.

What if I want to edit a car I downloaded from the community?

The same process applies. Make a copy of the downloaded vehicle folder, rename it, and edit the copy. This way you keep the original read intact and can always revert to it.

Are there tools that make Jbeam editing easier?

Some community members have built visual editors and spreadsheet tools for Jbeam files, but they are not official and may not work with every car or every version of BeamNG. A plain text editor is the most reliable method and works with any file.