ST Coilovers ST X galvanized steel (with fixed damping) - BMW 1 Series F20 M140i

ST X Coilovers – BMW 1 Series F20 M140i

The ST X Coilovers for the BMW F20 M140i are designed for drivers who want adjustable ride height, improved body control and a more purposeful stance in a straightforward road-focused suspension package.

Using a fixed-damping setup developed specifically for the application, the ST X offers a strong balance between everyday usability and sharper handling without the added complexity of manual damping adjustment.

Why choose ST X for your BMW M140i?

The F20 M140i responds well to suspension upgrades, particularly where the aim is to reduce body movement, lower the centre of gravity and improve overall chassis response.

The ST X is a strong option for owners who want the benefits of a height-adjustable coilover system but do not need manually adjustable damping.

For daily driving and fast-road use, it offers a simpler setup than the ST XA while still giving you the ability to fine-tune ride height.

Key Features

• ST X coilover suspension
• BMW F20 M140i application
• Adjustable ride height
• Fixed damping setup
• Vehicle-specific spring and damper tuning
• Improved body control
• Road and fast-road focused setup
• Galvanised steel damper construction
• Corrosion-resistant coating
• Developed using KW suspension technology
• Suitable for daily-driven performance cars
• Straightforward setup with no damping adjustment required

Fixed Damping Setup

The ST X uses a fixed damping configuration that is pre-set for the specific vehicle application.

This means there is no need to manually adjust rebound or compression settings after installation.

For many road-driven M140i builds, this simplicity is a real advantage.

The suspension is designed to provide a controlled and balanced response without requiring the driver to experiment with damper settings.

Adjustable Ride Height

The ST X allows the ride height of the BMW F20 M140i to be adjusted within the approved application-specific range.

This makes it possible to reduce arch gap, improve stance and lower the centre of gravity.

For road-driven cars, ride height should be selected with suspension travel, tyre clearance and geometry in mind rather than simply lowering the car as far as possible.

A full wheel alignment is strongly recommended after installation.

Galvanised Steel Construction

The ST X uses galvanised steel damper bodies with a protective coating designed to resist corrosion.

This provides a durable and cost-effective construction while keeping the kit positioned below the stainless-steel KW INOX-LINE range.

For cars used throughout the year, regular cleaning of the threaded adjustment areas is still recommended, particularly during winter when dirt, moisture and road salt can accumulate.

BMW F20 M140i Suspension Upgrade

The M140i combines strong performance with a rear-wheel-drive chassis that responds well to better suspension control.

The ST X can work well alongside upgrades such as:

• Performance tyres
• Uprated suspension bushes
• Adjustable suspension arms
• Chassis bracing
• Rear subframe upgrades
• Limited-slip differential
• Performance alignment settings

For fast-road builds, combining coilovers with a quality geometry setup can significantly improve steering response and overall chassis balance.

ST X vs ST XA

The ST X is the simpler option in the range, offering adjustable ride height with fixed damping.

The ST XA adds manually adjustable rebound damping, giving the driver greater control over ride and chassis behaviour.

For owners who simply want a lower stance, sharper handling and a well-developed road setup, the ST X is a strong choice.

For drivers who want the ability to fine-tune damping, the ST XA is the more flexible option.

ST X vs Lowering Springs

Lowering springs are a simpler and more affordable way to reduce ride height, but they retain the factory dampers and use a fixed lowering amount.

The ST X replaces both the springs and dampers and allows the ride height to be adjusted.

This makes it a more complete suspension upgrade for owners who want greater control over both stance and overall handling behaviour.

Road & Fast-Road Use

The ST X is particularly well suited to:

• Daily-driven M140i models
• Fast-road builds
• Owners wanting adjustable ride height
• Cars running upgraded tyres
• Drivers who prefer a simple fixed-damping setup

For drivers who want adjustable damping or more track-focused tuning, the ST XA or a higher-specification KW system may be more appropriate.

Electronic Damper Compatibility

Some BMW F20 M140i models are equipped with adaptive electronic dampers.

Where conventional coilovers replace the factory electronic dampers, the original adaptive damping function will no longer operate.

Depending on the exact vehicle and kit specification, an electronic damping cancellation solution may be required to prevent warning messages.

Please confirm the exact application before ordering if your M140i is equipped with adaptive suspension.

Professional Installation & Alignment

Professional installation is recommended for the ST X.

Once fitted, the vehicle should receive a full four-wheel alignment so that toe, camber and other geometry settings can be checked following the change in ride height.

For fast-road builds, a more performance-oriented geometry setup can further improve steering response and tyre utilisation.

Maintenance

The threaded height-adjustment sections and spring platforms should be kept clean and inspected regularly.

This is particularly important on cars used throughout winter, where road salt and contamination can build up around the adjustment collars.

Regular cleaning and suitable preventative maintenance will help keep the suspension adjustable over the long term.

BMW F20 M140i Compatibility

This ST X coilover kit is intended for applicable BMW F20 M140i models.

Exact fitment can vary depending on vehicle specification, axle loads and whether the car is equipped with electronic damping.

Please confirm your exact vehicle details before ordering.

If you're unsure which ST X kit your M140i requires, contact us and we'll help identify the correct application.

What's Included?

The ST X is supplied as a complete vehicle-specific coilover suspension system for the applicable BMW F20 M140i, including:

• ST X dampers
• Vehicle-specific springs
• Height-adjustment components
• Relevant installation components

Exact contents can vary depending on the selected application.

Explore More BMW M140i Parts

Looking to improve your M140i further? Explore our range of BMW F20 M140i parts and upgrades, including suspension, handling, braking and performance products.

BMW F20 M140i Parts – Shop upgrades specifically for the BMW F20 M140i.

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