• General
  • ladder chassis
  • Monohull
  • unibody
  • Tube frame and space frame
  • Back bone chassis
  • Self-supporting body
  • Window and door styles

The body is the body of the car, without the separate parts such as the chassis, the powertrain and the interior. We often speak of a "self-supporting body" when the body and chassis are designed as one unit and are also so strong that separate parts can be mounted directly on it. It is also possible that the bodywork is placed on the chassis and is therefore separated from each other. Various chassis and body construction methods are described on this page.

Ladder chassis:
The ladder chassis owes its name to the fact that the chassis actually resembles a ladder. A number of transverse beams are attached between two thick steel beams in the longitudinal direction. All components of the wheel suspension system are mounted on the longitudinal and transverse beams.
The ladder chassis is mainly used in cars that have to be able to carry a lot of weight, such as SUVs, pick-ups and off-road vehicles and trucks. Disadvantages are: a high weight, takes up a lot of space and are not flexible enough to absorb the torsional forces while driving.
An example of a ladder chassis is shown below:

The body is attached to the ladder frame with screw connections. The ladder chassis and the body can be separated from each other during repair work on the undercarriage or driveline. This can be seen in the image below:

The ladder chassis made it possible in the early twentieth century for Ford to mount different body shapes on one type of chassis on the assembly line. In the early days of the car it was common to buy a chassis that determined the make of the car, and for the car to be fitted with a body by a coachbuilder. This still happens in a similar way with trucks and buses.

Contemporary cars using a ladder chassis include the BMW I3 / I8, Chevrolet Silverado / Suburban / Tahoe, Ford Expedition, GMC Yokon, Jeep Wrangler, Mercedes-Benz G-class, Toyota Hilux / Land Cruiser / Tundra.

In a monocoque construction, there is no separate chassis and body. The load-bearing structure is formed by the shell, without internal reinforcements. An egg is a good example of this. The name "monocoque" is a combination of the Greek "mono" and the French "échelle coque" which stands for "hull scale". The monocoque can be constructed from profiled steel sheets and from carbon fiber. The latter variant has the advantage that the weight of the vehicle remains low. Because there is no separate chassis, this benefits the space in the passenger compartment and the engine compartment.

Vehicles fitted with a monocoque body include a Formula 1 race car and the McLaren F1 (left and right in the image below).

In today's cars, the unibody is often used. Unibody comes from the phrase “unitized body”. The unibody body consists of different box constructions, cross members and tubes. Not only the constructions of the body, but also the glued windows, the roof construction and the floor plates contribute to the rigidity of the body. The body and chassis are considered as one unit. The powertrain and chassis are attached to this body using a subframe confirmed. We therefore also speak of a “self-supporting body”.

The unibody is made up of separate parts that are welded, glued or screwed together. Because various parts are attached to each other, not everything has to be made of one type of material, such as steel. An important advantage of this is that the weight decreases. The use of lightweight materials such as aluminum and carbon fiber does not affect safety, as unibody vehicles usually contain crumple zones and other structures specifically designed to absorb the forces that arise in a collision.

Tubular frame and space frame:
In the case of a tubular frame, we also speak of a self-supporting body. A tubular frame, also known as a space frame, is a three-dimensional, highly complex structure of aluminum tubing attached to each other. The tubes form the basis of both the body and the chassis. The drivetrain, chassis and sheet metal parts are attached to these aluminum tubes. An example of this is from the Mercedes-Benz 300SL:

Audi also uses the term “space frame”. In the aluminum frame structure, all panels and plates contribute to the strength of the body. Due to the very sturdy aluminum sheet parts, the aluminum body is extremely strong and therefore very resistant to crashes, while the weight of the vehicle is reduced. The image below shows the construction of an Audi space frame.

Backbone Chassis:
The backbone chassis is made of one or more steel profiles that connect the front and rear axles. The backbone chassis is strong in relation to the weight. The disadvantage of this type of chassis is that the chassis offers no protection at all in the event of side collisions.

A car that uses the backbone chassis is the DeLorean DMC-12.

Self-supporting body:
The different body shapes are described in the paragraphs above. A unibody is an example of a self-supporting body. The underbody, bulkhead, roof panel, door pillars and even the glued windows form the load-bearing parts of the self-supporting body.

The non-load-bearing parts include the parts including the doors, the hood, the boot lid, the mudguards and the side windows. These parts are usually screwed to the body and do not provide body rigidity.

Window and door styles:
Window and door styles are often indicated by a letter. The front to back uprights are called the A-pillar, B-pillar, etc. (see bodywork image)

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