Audi Q3 8U Rear Brake Caliper Wheel Braking Unit Left N/S 8U0615403B

Audi Q3 8U Rear Brake Caliper Wheel Braking Unit Left N/S is an original brake system component from the Brake calipers and carriers group, designed for installation on the rear left axle of the vehicle. This used caliper allows for a technically sound replacement of a worn part, maintaining factory braking characteristics and compatibility with the Audi suspension design.

Specifications and technical data

• SKU: 8U0615403B
• Mark: Audi
• Condition: Used
• OEM Part Number: 8U0615403B
• Substitutable numbers: 8U0615403B, 8U0 615 403 B
• Location on the vehicle: Rear, Left
• Category: Calipers & Brackets

Purpose and function in the brake system

The presented caliper is dedicated for installation in the rear left part of the vehicle, where it is responsible for evenly pressing the brake pads against the disc and ensuring the stable operation of the entire system. As an Audi brand component, it maintains the correct mounting geometry, which translates into predictable brake performance and proper cooperation with other axle components.

The vehicle placement is clearly defined as rear – left side, which facilitates part selection when comparing with the existing caliper and minimizes the risk of error during repair planning.

Benefits of using an original Audi caliper

Using an original caliper in the Audi Q3 8U ensures:

• preservation of factory brake system performance parameters,
• proper fitment to the carrier, disc, and brake pads,
• appropriate structural rigidity, essential for repetitive braking,
• consistency with other rear axle components in terms of dimensions and mounting points.

The used component allows for an economical repair while maintaining the manufacturer's original specifications, which is particularly important in vehicles where compliance with service documentation and predictable braking behavior are prioritized.

Selection, installation, and technical aspects

When selecting a caliper for the Audi Q3 8U, it is crucial to verify compatibility with the manufacturer's markings and the vehicle placement. This model is intended for operation on the rear left side, therefore it should not be used interchangeably on the opposite side of the axle. Proper fitment reduces the need for installation modifications and allows for assembly in accordance with service procedures.

During installation, it is recommended to:

• inspect the condition of the brake hose and mounting points,
• check the freedom of movement of the piston and guide pins after installation,
• properly bleed the system after completing the work.

This approach allows you to fully utilize the potential of the used caliper and reduce the risk of uneven braking or overheating of friction elements.

Safe purchase of a used brake caliper

When choosing a used caliper for an Audi, it is worth paying attention to the compatibility with the OEM part number and any interchangeable numbers, as well as the actual technical condition of the component. Proper verification before installation helps avoid problems with leaks, piston seizure, or improper mechanism operation.

If you want to check step-by-step what to look for when buying used brake system components, read our guide: Second-hand brake system: how to safely choose discs, calipers, and ABS?. The article contains a practical checklist useful for assessing the condition of components such as the presented rear left caliper.

Expanding your Audi brake system upgrade

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

For drivers analyzing the cost-effectiveness of using original, aftermarket, and used parts, the following comparative material may also be helpful: Original, aftermarket, or used – which car parts are the most cost-effective?. It allows for a better assessment of when choosing a used brake caliper is technically and economically justified.