An inboard brake is an automobile technology wherein the disc brakes are mounted on the chassis of the vehicle, rather than directly on the wheel hubs. Its main advantages are twofold: a reduction in the unsprung weight of the wheel hubs, as this no longer includes the brake discs and calipers; and braking torque is applied directly to the chassis, rather than being transferred to it through the suspension arms.
The McLaren M23's rear brakes nestle between the universal joints and the transaxle
Alfa Romeo 75 rear transaxle
A disc brake is a type of brake that uses the calipers to squeeze pairs of pads against a disc or a rotor to create friction. There are two basic types of brake pad friction mechanisms: abrasive friction and adherent friction. This action slows the rotation of a shaft, such as a vehicle axle, either to reduce its rotational speed or to hold it stationary. The energy of motion is converted into heat, which must be dispersed.
Close-up of a disc brake on a Renault car
On automobiles, disc brakes are often located within the wheel
A drilled motorcycle brake disc
Front suspension and brake system on AMC Pacer with the rectangular open slots visible between the disc's friction surfaces