Getting a roblox vehicle suspension script chassis to feel right is honestly one of the hardest parts of game dev on the platform. If you've ever tried to make a car in Studio, you probably know the struggle. You either end up with a vehicle that flips over the moment you touch a curb, or something that feels like a literal brick sliding across a frozen lake. It's frustrating, but once you wrap your head around how the physics actually work, it becomes way more fun to tinker with.
Most beginners start by just slapping some wheels on a part and using a HingeConstraint. That works for a basic cart, but if you want something that looks and feels like a real car—with body roll, weight transfer, and actual bumps—you're going to need a custom script-based approach. We're talking about raycast suspension.
Why Raycasts Change Everything
In a standard roblox vehicle suspension script chassis, we don't usually rely on physical springs that you find in the "Constraints" tab. Instead, we use raycasting to "fake" the suspension. Basically, the script fires an invisible laser beam down from each corner of the car. It calculates how far that beam travels before it hits the ground.
If the ground is close, the script "pushes" the car up with a lot of force. If the ground is far away, the force is weaker. This creates a virtual spring. The reason we do this instead of using physical parts is because it's way more stable. Roblox physics can get a bit "jittery" when too many physical parts are colliding at high speeds. By using a script to handle the math, everything stays smooth.
The Logic Behind the Spring
To get a decent roblox vehicle suspension script chassis running, you have to understand a little bit of physics—specifically Hooke's Law. Don't worry, it's not as scary as it sounds. It just means that the force of a spring is equal to how much it's being compressed multiplied by its stiffness.
In your script, you'll calculate the "displacement." If your suspension is 2 studs long and the raycast hits something 1 stud away, your displacement is 1 stud. You multiply that by a Stiffness variable. But if you stop there, your car will bounce forever like a pogo stick. That's where damping comes in. Damping is like the "shock absorber" in a real car. It resists movement, slowing things down so the car eventually settles. Without damping, your car will literally fly off the map because the energy just keeps building up.
Setting Up the Scripting Environment
When you're ready to actually write the roblox vehicle suspension script chassis, you'll want to use RunService.Heartbeat or RunService.Stepped. You need this math to run every single frame. If you run it on a loop with task.wait(), the car will feel laggy and unresponsive because the physics engine is moving faster than your script.
You'll start by defining your variables: Stiffness, Damping, and SuspensionLength. You'll also need to know the mass of the car. A common mistake is using the same settings for a tiny go-kart and a massive semi-truck. The force you apply needs to be relative to the weight of the vehicle, or it'll either never leave the ground or launch into orbit.
Handling the Visuals
One of the cool things about a roblox vehicle suspension script chassis is that the physical "wheels" don't actually have to touch the ground. In fact, most high-end Roblox cars have wheels that are just for show (CanCollide set to false). The script handles the height of the car, and then you just move the wheel models to match where the raycast hit the ground.
This is a huge trick for performance. It prevents the wheels from getting stuck on tiny cracks in the terrain or clipping into walls. You just tell the wheel model: "Hey, go to the position where the raycast hit, and stay there." It looks perfect to the player, but the physics engine is having a much easier time because it's only calculating one big box (the chassis) instead of four spinning cylinders.
Tuning for Different Terrains
Once you've got the basic roblox vehicle suspension script chassis moving, the real work starts: tuning. This is where you spend hours changing a 5000 to a 5500 and seeing if it feels better.
If your car feels too "floaty," you need more damping. If it feels like it's vibrating or jittering, your stiffness is probably way too high for the weight of the car. For off-road vehicles, you want a long SuspensionLength and lower Stiffness so the wheels can soak up big rocks. For a race car, you want it stiff and low to the ground so it doesn't tilt too much when turning.
Avoiding Common Scripting Pitfalls
A big issue people run into with a roblox vehicle suspension script chassis is the "infinite flip." This usually happens when the car is upside down, but the rays are still hitting the "ceiling" (which the car thinks is the ground) and trying to push the car away from it. You need to add a check in your script to make sure the rays only fire when the car is relatively upright, or at least ensure the force is applied in the correct direction relative to the car's floor.
Another thing is network ownership. If you're making a multiplayer game, the player driving the car needs to have network ownership of the chassis. If the server is trying to calculate the suspension math while the player is trying to drive, you'll get horrible stuttering. Always use vehicleSeat:SetNetworkOwner(player) when someone hops in.
Making it Your Own
There are plenty of "free models" out there like A-Chassis which use a very complex roblox vehicle suspension script chassis. Those are great for learning, but they can be a nightmare to customize if you don't know what every line does. Building your own from scratch—even a simple one—gives you so much more power.
You can add things like anti-roll bars (linking the left and right suspension so the car doesn't tip over) or even active aero that changes the downforce based on speed. The possibilities are kind of endless once you stop relying on basic constraints.
It takes a lot of trial and error to get a roblox vehicle suspension script chassis feeling "triple-A," but it's one of those skills that separates okay games from the ones that people want to play for hours. Just remember to keep your math clean, use raycasts for stability, and never underestimate the power of a good damping value. Happy building!