BMW Polyurethane Subframe Bushing Kit - Revshift PSB-E9X-95A

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 Revshift

Revshift is a performance engineering and manufacturing company located in Metro Detroit, MI. Our parts are designed and manufactured all under one roof. We do the CAD work, TIG/MIG welding, CNC machining, and process/mold the polyurethane ourselves. Nothing is outsourced and nothing is overlooked.

Established in 2009, Revshift had one goal; Produce the highest quality performance products available, completely designed and manufactured in the Motor City. We started out with nothing more than a small workshop and a lot of ambition. Today, we have a full manufacturing facility with multiple CNC machines, TIG and MIG welding stations, and a polyurethane manufacturing department.

The employees of Revshift are dedicated to providing the highest quality products to our customers. Quality materials, technical expertise, and pride in workmanship combine to achieve this goal. We will meet every one of our customers’ expectations. We look forward to supplying you with the most reliable, well engineered, and highly respected performance parts for a long time to come.