Audi A4 B9 8W Brake Caliper Wheel Braking Unit Rear Left N/S 300X12MM 8W0615403M

Audi A4 B9 8W Brake Caliper Wheel Braking Unit Rear Left N/S 300X12MM is an original component from the Brake calipers and carriers group, designed for the rear left axle of the vehicle. This used brake caliper provides a functional service solution for drivers looking to restore the proper operation of the braking system while maintaining factory braking characteristics.

Specifications and technical data

• SKU: 8W0615403M
• Mark: Audi
• Condition: Used
• OEM Part Number: 8W0615403M
• Substitutable numbers: 8W0615403M, 8W0 615 403 M
• Location on the vehicle: Rear, Left
• Category: Calipers & Brackets

Purpose and vehicle placement

The presented brake caliper is dedicated for installation on the rear axle, on the left side. This placement is crucial for maintaining an even distribution of braking force between the right and left sides, which translates into vehicle stability during emergency braking and daily operation.

The component has been designed as part of a system working with a brake disc of a specific diameter and thickness, ensuring proper pad pressure, predictable braking force modulation, and consistency with the factory Audi braking system configuration.

Technical and functional characteristics

The caliper belongs to the group of components responsible for converting hydraulic pressure into mechanical force acting on the brake pads. The design intended for the rear axle accounts for specific thermal and mechanical loads typical for operation in this area of the vehicle.

• stable guidance of brake pads within the caliper,
• geometry properly matched to the disc with the indicated parameters,
• ability to operate in varied road and temperature conditions.

Thanks to the preservation of the factory design, the caliper works with the stock brake master cylinder, lines, and other system components, which facilitates service and limits the need for additional modifications.

Benefits of using an original Audi brake caliper

Choosing an original brake caliper for an Audi allows you to maintain the consistency of the entire system's operating parameters. Factory geometry and fitment minimize the risk of uneven pad wear, vibrations during braking, or improper piston retraction.

The most important advantages of using this component include:

• maintaining braking characteristics in line with the vehicle manufacturer's specifications,
• easier diagnostics and service thanks to compliance with Audi technical documentation,
• the ability to use standard installation and system bleeding procedures.

For the user, this means predictable vehicle behavior during braking, which has a direct impact on driving comfort and safety.

Selection, installation, and operation

Before installation, it is recommended to verify the compatibility of the caliper with the specific vehicle equipment version and to check the condition of mating components, such as brake discs, pads, and lines. Proper installation includes, among other things, correct positioning of the guide pins, the use of appropriate tightening torques, and careful bleeding of the system.

During operation, it is worth periodically checking the condition of the working surfaces, the freedom of movement of the guide pins, and the evenness of pad wear. This allows for early detection of any irregularities and helps maintain stable braking parameters over a longer period of use.

More Audi braking system components and technical guide

If you are planning a comprehensive repair or upgrade of the braking area in your Audi and need other elements from the same group, such as additional calipers, mounting brackets, or carriers, check out the available parts in the Audi brake calipers and carriers category.

When selecting used braking system components, a practical guide will be helpful, where you will find a checklist for assessing the condition of calipers, discs, and ABS components – detailed tips are included in the article "Second-hand braking system: how to safely choose discs, calipers, and ABS?".