BMW Rear Subframe Rear Bushing - Powerflex Race PFR5-422BLK

Product Information

A subframe mount bushing (also referred to simply as a subframe mount) is a vibration-isolating bushing used to connect the front and rear subframe to the vehicle’s main body or unibody. The subframe itself serves as a structural framework to mount key assemblies such as the suspension, engine, and transmission. Because the drivetrain and suspension are mounted to the subframe, they naturally transmit vibrations to the body of the car. The subframe mount acts as an additional cushion, absorbing vibrations, shocks, and road noise while allowing some flexibility in the subframe’s movement. This helps reduce stress on the vehicle’s body and provides a smoother, more comfortable ride.

There are a few common types of subframe mounts. In an OE application such as a stock vehicle, the mount is typically made of solid rubber, voided rubber (some holes to increase flexibility), or occasionally hydraulic-filled rubber. In performance and race applications, minimizing movement in the subframe is important to maintain correct suspension geometry during high G-loads, so going to polyurethane mounts or reinforcements is a popular upgrade.

Aging or torn subframe mounts can cause several issues, including poor handling or tracking of the wheels, inability to maintain an alignment with abnormal tire wear, and bangs or clunks when transferring load front to back, like when braking or accelerating. Inspect the mounts for cracks or tears, or leaks if the mount is hydraulic.

• Bangs and Clunks: If you are experiencing clunks or bangs when going over bumps, or when braking or accelerating is a sign that the entire subframe is moving around excessively and the mounts may be bad.
• Increased Vibration (NVH): Subframe mount bushings are designed to isolate vibrations from the engine and suspension. When they go bad, they will not effectively absorb NVH, and you will feel more vibrations transferred to the cabin.
• Handling and alignment issues: Since the suspension is connected to the subframe, the mounts must be in good shape. If they aren't, the suspension will have more freedom of movement independent from the car body/frame, and it may also be difficult to maintain an alignment.
• Excess Movement: With the car securely off the ground, use a lever like a pry bar between the subframe and the body of the car. If there is excess movement and it is easy to shift the subframe, the mounts should be replaced.

About Powerflex

Installation instructions are included in all Powerflex kits

Powerflex has extensive knowledge and design experience in automotive suspension and chassis systems. These design skills have been combined with advanced polyurethane manufacturing techniques leading to the development of a wide range of high-performance automotive polyurethane components that are second to none in quality and performance.

Street Purple - Powerflex Street bushings are purple in color and are meant for street sport applications. Order this compound for daily driven cars and when ultimate performance is not a priority. In some positions, the street compound bushing may also be yellow.

Racing Black - Powerflex Racing bushings are significantly stiffer than their street counterparts, and are designed for vehicles that are driven on race tracks for minimum bushing deflection. Occasionally racing black bushings are denoted for use on street applications in positions where excess load puts significant demand on a bushing and NVH is not effected by the stiffer material.

All component manufacturing is carried out by our in-house engineers utilizing the latest automatic processing equipment to ensure premium quality. Testing of new components is carried out both on test rigs and on the actual vehicle the parts are designed for. Stainless steel and aluminum components are also machined in-house on the latest computer-controlled equipment to ensure perfect repeatability and exceptional quality.

The special type of polyurethane used by Powerflex is an advanced proprietary material which has unique properties. This ensures that each product not only offers the high-performance capabilities our customers expect, but also the exceptionally long life and quality they demand - without increased vibration or noise.