The Types of Control Arms

There isn't a single fixed number of types, as they can be classified in several ways: by their physical design, the number of mounting points, and the specific axle type they are used on.

Here are the primary ways to categorize control arms:

1. By Physical Design and Mounting Points

This is the most common way to classify control arms.

A-Arm / Wishbone

Description: This is the classic and most recognizable design. It's a V-shaped or A-shaped component with two inner mounting points (to the chassis) and a single outer ball joint (to the knuckle).

Usage: Extremely common in independent front suspensions of cars, SUVs, and light trucks. It provides excellent stability and control over the wheel's movement.

Trailing Arm

Description: A relatively simple, straight or slightly curved arm that is mounted parallel to the vehicle's length. It allows primarily for up-and-down motion and is good at resisting front-to-back forces.

Usage: Frequently used in solid rear axle suspensions, where it controls fore/aft movement. It's also the basis for the suspension on many motorcycles and the front of some older cars.

Multi-Link

Description: This isn't a single control arm but a system. It uses multiple separate arms (typically 3, 4, or 5) to control the wheel's position. Each arm is responsible for a specific force (lateral, longitudinal, etc.).

Usage: Found on high-performance vehicles and luxury cars for its ability to provide an optimal balance of ride comfort and sharp handling. Many modern "multi-link" rear suspensions are based on a double-wishbone or Chapman strut design, broken down into individual links.

Chapman Strut / Reverse A-Arm

Description: A variation where a single transverse arm (like the bottom of an A-arm) is combined with a strut assembly. The strut itself acts as the upper pivot point.

Usage: A simpler and more cost-effective alternative to a double-wishbone setup, used by manufacturers like Lotus and in many front-wheel-drive vehicles.

2. By Configuration in the Suspension System

Upper Control Arm

Located at the top of the wheel assembly in a Double Wishbone suspension. It is typically shorter than the lower arm.

Lower Control Arm

Located at the bottom of the wheel assembly. It is usually stronger and bears most of the vehicle's weight and road impact forces. In a MacPherson Strut suspension, this is the only control arm, as the strut replaces the upper arm.

Double Wishbone Suspension

This is a complete suspension type that uses two distinct A-arms (an upper and a lower) per wheel. It's considered a high-performance design.

3. By Application and Adjustability

Stock/OEM Control Arms

Standard arms that come with the vehicle from the factory.

Adjustable Control Arms

Aftermarket arms (often used in lifted trucks, lowered cars, or race vehicles) that feature threaded heim joints or sleeves to allow for precise adjustment of camber, caster, or wheelbase.

Forged vs. Cast Control Arms

This refers to the manufacturing process. Forged arms are generally stronger and lighter, used in high-performance applications, while cast arms are common for standard production vehicles.