A car’s frame is its main structural piece that holds everything together. All the other parts of your car are connected to this. Its most basic form is two rails held together by one frame cross member or more. When a car is built on a frame, the type of design is referred to as body-on-frame. The frame is a key piece in the chassis, which serves as the support system for your vehicle, much like the skeleton works to support your body.

Originally, all vehicles were built on frames. Today, because of different regulations, almost all cars are built on unibody frames. The last car that was widely produced using a chassis and frame was discontinued in the 1970s. However, most trucks and buses are still built on frames, with the most common being the ladder-type. Keep reading for an overview of the most common types of frames available today.


The ladder frame named that because it looks like a ladder is the oldest and simplest frame type. Basically, it has two long rails running parallel with cross members running between them. Manufacturers widely used them in cars until the 1940s, when the unibody design became more popular. Today, they are primarily used on trucks and SUVs. Because of the strength this design offers, it is popular for heavy-duty vehicles and holds up well to abuse. However, it also means that they need to be monitored closely because if a frame breaks, major problems can occur in your truck.


A unibody design has the frame of the vehicle incorporated into the car body’s sheet metal. Depending on the type of vehicle, there may be subframes that need reinforcement. These designs first began to appear in the 1930s. They became prevalent in the 1940s and are the primary frame design for crossovers, minivans, and cars today. Additionally, several types of smaller SUVs also use the unibody frame design. For example, the Dodge Durango uses this type. This design increases the gas mileage of your vehicle because it is lighter and more aerodynamic.

The frame is a crucial part of a vehicle’s chassis, still used in buses and trucks. These heavy-duty vehicles tend to rely on the ladder-style frame because it is stronger and can handle more abuse. However, most cars built today have a unibody design that incorporates the frame into the car’s body. In addition, minivans, crossovers, and smaller SUVs will also likely have a unibody design because it makes them lighter and more aerodynamic.