What is the benefit of having external reservoirs on these coilovers?

External reservoirs help keep the damping fluid cooler under extreme conditions. This prevents the fluid from overheating and losing its effectiveness, ensuring consistent performance during long track sessions or hard driving.

How do the adjustable top mounts improve handling?

The camber-adjustable front top mounts allow you to dial in more negative camber. This can significantly improve cornering grip by keeping the tire flatter on the road surface when the vehicle is leaned over in a turn.

What is the difference between low-speed and high-speed compression adjustment?

Low-speed compression affects how the suspension reacts to gradual weight transfers, like during braking or accelerating. High-speed compression controls how the suspension handles sudden impacts, such as hitting a bump or curb at speed.

AST 06-08 BMW Z4 M Coupe/Convertible - E85/E86 5300 Comp Series Coilovers

Specifications

Brand: AST
Part #: RAC-B1010SD
UPC: astRAC-B1010SD

AST 06-08 BMW Z4 M Coupe/Convertible - E85/E86 5300 Comp Series Coilovers

Name: AST 06-08 BMW Z4 M Coupe/Convertible - E85/E86 5300 Comp Series Coilovers
Brand: AST
Price: 8627.84 USD
Availability: InStock

$8627.84

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Fits 2006-2008 BMW Z4 M Coupe/Convertible. AST 5300 Comp Series Coilovers offer 3-way adjustability for track-tuned performance.

Key Features

3-way adjustable dampers — independently tune rebound, low-speed compression, and high-speed compression for track-specific performance.
External reservoirs — provide consistent damping force and heat dissipation during demanding track conditions.
Monotube design — handles heavy side loads and braking forces common in racing.
Adjustable spring rates — allows for further customization of your suspension setup.
Camber-adjustable front top mounts and solid rear top mounts — offer more alignment adjustment for improved front-end grip and handling.
Ride height adjustable — fine-tune your vehicle's stance and weight distribution.

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Fits this vehicle

BMW Z4 2006-2008

Product Details

Already running a track-focused setup? The AST 5300 Comp Series Coilovers are the next piece to fine-tune your 2006-2008 BMW Z4 M Coupe/Convertible. These are serious suspension components for dedicated track use, allowing you to adjust rebound, low-speed compression, and high-speed compression independently. The AST RAC-B1010SD kit is built around a monotube design with external reservoirs for consistent damping under heavy loads.

With the AST 5300 Comp Series, you get full control over your suspension's response. You can adjust the rebound, which controls how quickly the shock returns after compression, through 12 distinct positions. You can also adjust both low-speed and high-speed compression separately. Low-speed compression affects how the suspension reacts to gradual weight shifts, like during cornering or braking. High-speed compression handles quick impacts from bumps or rough surfaces. This level of tuning helps reduce body roll, improve steering response, and keep your tires planted for better traction.