Suspension Secrets Solid Front Control Arm Bushes - BMW F20 M135i/M140i

Suspension Secrets Solid Front Control Arm Bushes – BMW F20 M135i / M140i

Improve braking stability, steering accuracy and front-end grip with Suspension Secrets Solid Front Control Arm Bushes for the BMW F20 M135i and M140i.

The factory front control arm bushes use a soft, oil-filled rubber construction. Under harder driving, these bushes can flex significantly, allowing unwanted movement in the front suspension geometry.

This can contribute to vague steering, reduced accuracy during high-speed cornering and nervousness under heavy braking.

The Suspension Secrets solution replaces this compliant arrangement with machined billet aluminium housings fitted with BMW OEM solid bushes, helping create a more precise and confidence-inspiring front end while retaining good road refinement.

Why Upgrade the Front Control Arm Bushes?

The front control arm bushes play an important role in maintaining suspension geometry under load.

When the factory bushes flex, the position of the control arms can move relative to the chassis.

This can affect:

• Steering accuracy
• Front toe angle
• Braking stability
• Front-end grip
• Cornering consistency

Replacing the soft OEM bushes with a more solid arrangement helps reduce this unwanted movement.

Key Features

• Designed for BMW F20 M135i and M140i
• Machined billet aluminium housings
• BMW OEM solid bush inserts
• Improved braking stability
• More accurate steering
• Improved turn-in response
• Reduced front suspension deflection
• Reduced unwanted toe-angle change
• Can help reduce understeer
• Improved dynamics on road and track
• Designed to retain good road refinement
• Fits OEM F20 control arms

Improved Braking Stability

One of the biggest benefits of this upgrade is improved stability under hard braking.

The original oil-filled bushes can deform as braking forces load the front suspension, allowing the wheel geometry to shift.

This can contribute to the nervous side-to-side movement sometimes experienced under heavy braking.

Reducing bush deflection helps keep the front suspension more stable and predictable.

More Accurate Steering

The more rigid bush arrangement reduces unwanted control arm movement.

This can provide:

• Sharper steering response
• More consistent feedback
• Greater accuracy
• Improved confidence during high-speed cornering

For drivers who find the standard F20 front end slightly vague, this can be a particularly worthwhile chassis upgrade.

Reduced Toe Deflection

As the OEM bushes compress and move under load, the front toe angle can change.

This means the wheels may no longer maintain the geometry set during static alignment.

The Suspension Secrets solid bushes help reduce this deflection, keeping the front suspension more consistent during harder driving.

Reduced Understeer

Reducing unwanted toe change and control arm movement can help the front tyres maintain a more consistent position during cornering.

This can contribute to:

• Improved front-end grip
• Sharper turn-in
• Reduced understeer
• More predictable chassis balance

Improved Turn-In Response

Less compliance in the front control arm mounting means steering inputs can translate more directly into front-wheel movement.

This can make the car feel more responsive and immediate when entering a corner.

Machined Billet Aluminium Housings

The Suspension Secrets bushes use machined billet aluminium outer housings.

These provide a rigid mounting structure around the bush and remove much of the compliance associated with the standard oil-filled rubber design.

BMW OEM Solid Bush Inserts

Rather than using a completely rigid metal bearing, the kit uses BMW OEM solid bush inserts within the billet housings.

This provides a good compromise between:

• Reduced suspension deflection
• Improved steering precision
• Performance
• Road usability

Minimal Impact on NVH

Suspension Secrets states that the upgrade does not increase noise, vibration or harshness.

Because the design still uses a BMW OEM solid bush rather than a fully rigid motorsport joint, any change in refinement should be relatively limited.

For RCC, we would describe this as a performance-focused upgrade designed to retain good everyday road usability without introducing a noticeable increase in NVH under normal driving conditions.

Road & Track Performance

These bushes are suitable for both road and track-focused cars.

They are particularly useful for:

• Fast-road builds
• Trackday cars
• Performance tyre setups
• Uprated suspension systems
• More aggressive geometry setups

Works Well With Other Suspension Upgrades

The bushes pair well with:

• Coilovers
• Lowering springs
• Uprated dampers
• Anti-roll bars
• Adjustable suspension arms
• Camber/caster plates
• Performance geometry setups

Reducing front control arm compliance allows the rest of the suspension setup to work more consistently.

Important Fitment Note

These bushes are designed specifically for the OEM BMW F20 front control arms.

They will not fit BMW M4 lower control arms.

If your F20 has been converted to M4 LCAs, a different bush solution is required.

Professional Installation Recommended

Bush replacement requires removal of the control arms and installation of the new bush assemblies.

Professional fitting is recommended.

After installation, the vehicle should receive:

• Suspension inspection
• Wheel alignment
• Toe adjustment
• Fastener checks

Geometry Setup

A professional geometry setup is strongly recommended after fitting.

This helps ensure the improved suspension control is matched with correctly set:

• Front toe
• Camber
• Tracking

Vehicle Fitment

BMW 1 Series F20

Compatible models:

• BMW M135i F20
• BMW M140i F20

Designed for:

• OEM F20 front control arms

Not compatible with:

• BMW M4 lower control arms / LCAs

What's Included?

Each kit includes:

• 1 pair Suspension Secrets Solid Front Control Arm Bushes
• Machined billet aluminium housings
• BMW OEM solid bush inserts

Explore More BMW F20 Suspension

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Suspension Secrets – Browse the wider Suspension Secrets chassis and geometry range.

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Suspension Arms & Alignment – Browse geometry and chassis adjustment components.

Suspension & Handling – Explore coilovers, springs, bushes and chassis upgrades.