Chaos Vehicle drift vs arcade kart physics: a UE5 guide

You set up a car with Chaos Vehicles and want a kart racer drift: hop, slide around a hairpin, steer the line with the stick and come out with a boost. You lower the rear friction and pull the handbrake. The car either spins out or snaps back into grip, and every fix breaks something else.

That’s normal. A Chaos Vehicle drift is what happens when the rear tires of a simulated car run out of grip, so you are tuning the unstable edge of a tire model, and every setting you touch changes normal driving too. Arcade kart racers often go the other way: custom physics on one simple body, with the drift as a state the game designs.

I build Kart Racing Drifting Physics, a kart plugin that takes the second route, so I’m not neutral here. I’ll still cover where that route falls short, and when Chaos Vehicles is the better pick.

Chaos Vehicles

Handling comes out of a chain

Throttle, brake, steering

Engine: torque curve and RPM

Gearbox and differential

Each tire: load, slip, grip limit

The car body moves

A drift happens if the rear tires slide

Arcade kart

Handling is designed

Throttle, steering, drift button

Kart state: driving, hop, drift, boost, air

Forces chosen for that state

One box body moves

A drift starts when the player asks for one

Two ways to move a vehicle. In one the drift is a side effect of the tires, in the other it is a state of the game.

What Chaos Vehicles simulate

Chaos Vehicles is the built-in option for UE5 vehicle physics. Epic describes it as Unreal Engine’s “lightweight system for performing vehicle physics simulations”. It models a simplified version of how a real car works: an engine sends torque through a gearbox and a differential to the wheels, and each tire turns that torque and its sideways slip into forces on the body.

To follow Epic’s setup guide, you need a skeletal mesh, a physics asset, an Animation Blueprint with the Wheel Controller node, a vehicle Blueprint based on WheeledVehiclePawn, wheel Blueprints based on ChaosVehicleWheel and a torque curve. After that come the settings you end up tuning:

Part	Where	Settings you touch
Engine	Vehicle Movement Component, Mechanical Setup > Engine Setup	Torque Curve, Max Torque, Max RPM, Engine Brake Effect
Gearbox	Mechanical Setup > Transmission Setup	Automatic Transmission, Forward Gear Ratios, Final Ratio, Change Up RPM, Change Down RPM
Differential	Mechanical Setup > Differential Setup	Differential Type (all, front or rear wheel drive), Front Rear Split
Tires	Each wheel Blueprint	Friction Force Multiplier, Cornering Stiffness, Side Slip Modifier, Slip Threshold, Skid Threshold, Lateral Slip Graph
Suspension	Each wheel Blueprint	Spring Rate, Spring Preload, Suspension Damping Ratio, Suspension Max Raise, Suspension Max Drop, Wheel Load Ratio
Brakes and steering	Wheel Blueprint and Steering Setup	Max Brake Torque, Max Hand Brake Torque, Affected by Handbrake, Max Steer Angle, Steering Curve
Body	Vehicle Setup	Mass, Center Of Mass Override, Drag Coefficient, Downforce Coefficient

The wheels themselves are not physics bodies, which is easy to miss. Each wheel finds the ground with a trace (Sweep Shape: a ray by default, a sphere or the wheel’s shape). Arcade vehicles find the ground the same way. The two approaches differ in what happens once the tire touches the road.

How a Chaos tire makes grip

In Unreal Engine 5.7, the wheel code works roughly like this:

Each tire has a grip budget: how hard it is pressed into the ground, times the surface friction, times Friction Force Multiplier.
The sideways force grows with the slip angle, which is the angle between where the wheel points and where it actually moves. Cornering Stiffness sets how fast it grows (or the Lateral Slip Graph, if you fill one in).
Throttle, brakes and cornering all draw from that same budget.
When a tire asks for more than its budget, the force is cut to the budget and then scaled down by Side Slip Modifier. Epic’s tooltip describes it as “Wheel Lateral Skid Grip Loss, lower number less grip on skid”.

Simplified from the Chaos wheel code in UE 5.7, with an empty Lateral Slip Graph. Accelerating or braking with the same tire uses up part of the same budget.

Why a Chaos Vehicle drift fights the model

In Chaos Vehicles, a drift is the rear tires sliding past their grip budget while the fronts keep more of theirs. The model has no concept of a drift. It only knows load, slip and friction. That’s why a slide feels real, and also why it’s hard to make predictable: a car past its grip limit is unstable, and real drivers hold it there with throttle and counter-steer. Each of the usual tricks for taming that slide has a side effect.

Lower the rear friction

Drop Friction Force Multiplier (or Cornering Stiffness) on the rear wheel Blueprint and the rear lets go sooner. It also lets go sooner everywhere else: in normal corners, under braking and over bumps. And since Friction Force Multiplier sets the budget that throttle and brakes share, a rear-drive car loses traction off the line as well.

You can change it only while drifting with the Set Wheel Friction Multiplier node, which leaves normal driving alone. Unless you blend it back, though, grip returns in one step and the car snaps straight.

Pull the handbrake

Max Hand Brake Torque brakes the wheels that have Affected by Handbrake, usually hard enough to lock them. A locked tire slides, and the car starts to rotate. That gets you into a slide but won’t keep you in it, because a locked wheel is a braking wheel: the car scrubs off speed, and a kart racer drift is supposed to keep it.

Make sliding softer

Side Slip Modifier decides how much grip is left once a tire slides, and the Lateral Slip Graph shapes the sideways force across slip angles. Leave more grip in the slide and your drift gets easier to hold. So does every other slide: a spin after a wall hit, or a landing at an angle, now slides like your drift.

Add your own forces and torques

The Vehicle Movement Component has an Arcade Control section with Torque Control, Target Rotation Control and Stabilize Control. Epic’s tooltip for the first two reads “Arcade style direct control of vehicle rotation via torque force”. You can also add your own side force or yaw torque in Blueprint while a drift button is held.

This works up to a point. Past it, two systems push the same body: your forces rotate the car, every tire answers with its own slip force, and tuning one changes the other.

Weight transfer sits under all of it

With Wheel Load Ratio near 1, each tire’s grip follows the load on it (Epic’s tooltip says a lower value “cures lift off over-steer”). Braking, bumps and suspension settings all shift grip between the axles. That’s realistic, and it makes a drift hard to repeat.

To see it for yourself, create a Blueprint project from the Vehicle template and drive one corner and one hard stop. Then lower Friction Force Multiplier in the sports car’s rear wheel Blueprint (SportsCar_WheelsRear) and drive both again. Watch what changed besides the corner.

Chaos Vehicles can drift, and a good powerslide in a car game feels great. The kart racer drift is the hard case: a button that commits you, a predictable angle, a stick that tightens or widens the line, no speed loss and a boost at the end. None of those are tire properties, so you end up faking each one on top of a model that keeps pulling the car back toward what a real car would do.

How a custom arcade vehicle is built

There are two common routes to UE5 arcade car physics: tune Chaos Vehicles with assists, or write the vehicle yourself. If you write it yourself, Unreal Engine custom vehicle physics for an arcade game comes down to the same few parts you’d build in any engine. Toyful Games’ breakdown of their car (in the reading list at the end) uses three forces per tire: suspension, steering, and acceleration with braking.

One box that simulates physics. The model is a visual mesh on top with no collision, so you can swap it without touching the handling.
A line trace down from each wheel point, used as a spring. The more the spring is compressed, the harder it pushes, and damping stops the bounce.
Grip you choose. A sideways force removes some or all of the sideways slide, and how much is a number you pick, not the output of a tire curve.
Steering as a turn rate, from a curve by speed, with a cap on how fast the body may rotate.
States you design: ground, air, hop, drift and boost. Each state decides which forces apply and how strong they are, so the game enters, holds and leaves a drift on purpose.
A fixed physics step. Springs and timers depend on the step size, so all of it belongs in a fixed-rate physics tick. See Async physics in Unreal Engine.

The usual arcade setup: one body, four trace springs and a few forces you design, instead of engine, gearbox and tire models.

An Unreal Engine arcade vehicle built this way does exactly what you tell it. That’s the reason to build one, and also its main cost, because it does nothing you didn’t design (more on that in the limits section).

How Kart Racing Drifting Physics does it

I took this route for Kart Racing Drifting Physics, and each of those parts has a place in the editor:

The physics body is one box, Kart Collision. The rigged kart, the rider and the particles only follow it. See Using your own kart model.
The springs are line traces cast from the Suspension Locations. See Suspension.
Speed and steering come from Max Acceleration, Max Speed, and a Turning Curve capped by Max Angular Velocity. See Speed, acceleration and turning.
The drift runs through phases, each with its own settings: the hop, a short slip, the drift and a correction after it. Two curves turn the stick into the drift’s direction and rotation, and boost stages charge while you hold the drift. See Drifting.
Boost pads and items all call one Set Boost node. See Boosts and items.
All of it runs in Unreal’s async physics tick at a fixed 60 Hz.

Details panel of the example kart, Kart Base Settings > Drifting, with Drift Curve set to FC_DriftVectorScaleByInput and Drift Angular Velocity Curve set to FC_DriftAngularVelocityByInput — Two curve assets shape every drift: how sideways the kart travels and how fast it rotates, by stick position.

The drift itself, phase by phase, is in How arcade kart drifting works.

Chaos Vehicles and arcade kart physics side by side

	Chaos Vehicles	Kart Racing Drifting Physics
Made for	Vehicles that behave like real ones: cars, trucks, motorcycles, any number of wheels	Arcade kart racers
Physics body	The vehicle’s skeletal mesh and its physics asset	One box, Kart Collision. The model is a separate mesh on top.
Ground contact	A trace per wheel (ray, sphere or wheel shape)	A line trace spring per Suspension Location
Grip	Tire model: load, slip angle and a grip budget	Designed grip that changes with the kart’s state
Speed	Torque curve, gears and differential	Max Acceleration and Max Speed
Steering	Steered wheels and tire slip	Turning Curve by speed, capped by Max Angular Velocity
Drifting	Emerges when the rear tires slide	Built in: hop, slip, drift and post-drift correction, shaped by two curves
Boosts	Your own logic, for example with a thruster	Drift boost stages, plus Set Boost for pads and items
Where you tune	Engine, transmission, differential and wheel Blueprints	The details panel of `BP_KartPawn`, under Kart Base Settings
Multiplayer	The movement component replicates. Epic’s Chaos Modular Vehicles support resimulation (client prediction with rewind) natively.	Server-authoritative with client prediction on Physics Prediction, coming in 1.1 for UE 5.7. Coming in 1.1

Which one to pick

Custom arcade physics is the better fit when:

your game is a kart racer, with hop drifts, boost stages, items and boost pads;
a drift should start from a button and follow the stick, the same way every time;
you want to tune by feel, with numbers like top speed and turn rate;
speed should never depend on gears or engine RPM.

Chaos Vehicles is the better fit when:

you want a sim or simcade feel, where the car behaves like a car, with weight transfer, gears and tire grip;
you need many vehicle types, from trucks to motorcycles;
vehicles are one feature among many, like a buggy in a shooter (Epic’s Vehicle template, with “a sports car and an offroad vehicle with a double wishbone suspension”, is a quick start);
vehicles should break apart, in which case look at Chaos Modular Vehicles.

Arcade racers with cars sit somewhere in between. For powerslides that still feel like a heavy car, start from Chaos Vehicles and add assists. If drifting is your core mechanic, with a button and a designed angle, a custom vehicle means a lot less fighting. Matthew Harris’s GDC talk “Vehicle Feel Masterclass” (in the reading list) is about exactly this balance.

If you’re still unsure, answer these five questions:

Does the player press a button to drift, or does the drift come out of driving?
Must the same input give the same drift every time?
Do you need gears, RPM or engine sound tied to a real engine?
Who tunes the handling: a designer going by feel, or someone who knows car setup?
How many kinds of vehicle does the game need?

If your answers were button, yes, no, feel and one, go custom. If most of them went the other way, Chaos Vehicles will serve you better.

Limits of the arcade approach

Nothing emerges for free. Landings, steep slopes, walls and bumps between vehicles each need a designed answer, and in your own vehicle you write and tune every one of them. The plugin has steep slope settings today, and wall response and kart collisions are coming in 1.1. Coming in 1.1
There’s no drivetrain, so no gears and no RPM. Engine sound has to follow speed or throttle instead.
A line trace only sees one point. A round tire meets a curb along its edge, while a trace only notices the curb when its point crosses it, so sharp steps can feel harsher than with a real wheel. Keep curbs and ledges gentle in your level design.
The plugin’s defaults are tuned for a 60 Hz step and a 1000 kg kart. Change either one and you re-tune.
The plugin is built for karts. For trucks, motorbikes or a realistic car it’s the wrong tool.
Players who like tuning gear ratios, differentials and tire grip won’t find any of that, because none of it is simulated.

Skip the hard part

If your game is a kart racer, Kart Racing Drifting Physics gives you this kind of custom arcade vehicle as one Blueprint, BP_KartPawn: line trace suspension on one box, hop and drift phases shaped by two curves, drift boost stages, Set Boost for pads and items, and a rigged kart you can replace. Owners also get an example project with a desert race track. It runs on Unreal Engine 5.5 to 5.7 on Windows, and you don’t need C++. Multiplayer is coming in version 1.1 for Unreal Engine 5.7. Coming in 1.1

Drive it first: the free Windows demo runs without Unreal Engine.
See how it is set up in Getting started and Drifting.
Get it on Fab.

Arcade kart physics vs Chaos Vehicles: why a Chaos Vehicle drift is so hard to tune