Skateboard Chassis Assembly

Overview

The skateboard chassis is the rolling platform of the electric car — the flat structural base that carries the HV Battery Pack in its centre and mounts the suspension, steering, brakes, wheels and drive units around it. The name comes from its shape: viewed from the side it is a low, flat board with wheels at each corner, onto which any number of different upper bodies can be set. By concentrating the heavy battery low and between the axles, the skateboard gives the car a low centre of gravity, a flat floor, and a structure that is largely shared across a family of vehicles.

How it's built / Construction

The skateboard is built around the battery tray, which is itself a structural member. Around it sit four corners, each a Suspension Corner combining a control-arm geometry, a spring and damper, a wheel bearing and upright, and a Brake Corner. The front is typically a double-wishbone arrangement for precise camber control; the rear is a five-link independent setup that locates the wheel in all directions while isolating road noise.

Front and rear subframes — often large aluminium high-pressure die-castings that replace dozens of stamped-and-welded parts — bolt to the main structure through rubber bushings that isolate vibration. The subframes carry the Electric Drive Unit, the lower suspension arms, and the Steering Rack (EPS). The rack is an electric power-steering unit that converts steering-wheel angle into tie-rod motion. Each Wheel Assembly bolts to a hub on the upright and connects to the drive unit through a half-shaft.

Key specifications explained

Wheelbase (2,875 mm) is unusually long relative to overall length because there is no engine bay to package; pushing the wheels to the corners maximises the floor area for the battery and the cabin space above it. Track width (~1,580 mm) and a low centre of gravity together resist body roll and give the car its planted feel.

Suspension type is a cost-versus-refinement trade: a multi-link rear is heavier and pricier than a torsion beam but controls the wheel far better under the high mass of an EV. Steering is fully electric — there is no hydraulic pump — so steering effort and feel are tuned in software, and the same Steering Rack (EPS) supports lane-keeping inputs from the ADAS Sensor Suite. Brakes are conventional friction discs at each Brake Corner, but they do less work than in a combustion car because regenerative braking through the Electric Drive Unit handles most deceleration; the friction brakes blend in only for hard stops.

Manufacturing & assembly

The skateboard is assembled on its own line and arrives at vehicle final assembly as a complete rolling unit. Subframes are built up with their suspension arms, the Steering Rack (EPS), and the Electric Drive Unit pre-installed, then bolted to the battery-tray structure. The Wheel Assembly and Brake Corner are fitted, brake lines and the low-voltage harness routed, and the unit is checked for wheel alignment and corner weights.

At the marriage station the loaded skateboard is raised on a fixture and the painted Body-in-White is lowered onto it; a ring of bolts ties the battery sill and subframe pickup points to the body, the high-voltage and coolant connections are made to the Thermal System, and the car becomes a single structure. This decoupled build — body up top, skateboard below — lets the two halves be manufactured and tested in parallel.

Role in the vehicle / where it fits

The skateboard is the mechanical backbone. It transfers every road load — cornering, braking, bumps — between the tyres and the Body-in-White, and it carries the HV Battery Pack as a stressed member that stiffens the whole car in torsion. It hosts the Electric Drive Unit that drives the wheels and the Steering Rack (EPS) that aims them. Crash loads from the front and rear crumple zones feed into and around the battery tray, which is engineered never to be breached in a survivable impact.

Dynamics and tuning

The skateboard's mass distribution is the foundation of how the car drives. With the HV Battery Pack low and central, the centre of gravity sits below the wheel centres, which suppresses body roll and makes the car feel planted in corners. The long wheelbase and wide track resist pitch and yaw. The Suspension Corner geometry is tuned for camber gain in roll so the tyre stays flat to the road, while bushing and damper rates trade ride comfort against body control — a harder problem in an EV because the sprung mass is high. Anti-roll bars at each axle balance understeer and oversteer.

Steering feel is shaped entirely in the Steering Rack (EPS)'s software, since there is no hydraulic feedback path; the same actuator accepts torque requests from the ADAS Sensor Suite for lane-keeping and parking. Braking is a blend: the Electric Drive Unit supplies regenerative torque first and the friction Brake Corner fills in for hard or low-speed stops, with the Low-Voltage Electronics managing the handover so the pedal feels seamless. Wheel sizing, tyre compound, and unsprung mass at each corner round out the character, from a soft long-range tune to a stiff, low-ride-height performance setup.

Variants & alternatives

A single skateboard typically underpins several body styles — sedan, SUV, pickup — by changing only the upper body and the wheelbase via a stretched centre section. Drive variants add or remove a front Electric Drive Unit for RWD or AWD. Air suspension can replace coil springs at each Suspension Corner for ride-height adjustment, and larger Brake Corners and wheels distinguish performance trims.

The alternative to a skateboard is a conventional unibody with the battery fitted into a floor cavity rather than forming the structure — common on EVs converted from combustion platforms, but heavier and less space-efficient. The purpose-built skateboard, sharing one platform across many vehicles, is the dominant approach for clean-sheet EV programmes. The trade it makes is clear: by committing the whole centre of the car to a flat battery and mounting the Electric Drive Unit, Suspension Corner, Brake Corner, and Steering Rack (EPS) around it, the designer gains cabin space, a low centre of gravity, crash structure, and a reusable platform — at the price of a fixed floor height and a structure tightly coupled to one battery format. For high-volume electric cars that trade has proven overwhelmingly worth making.