Suspension Secrets Front Offset Caster Bushes - BMW F20 M135i/M140i

Suspension Secrets Front Offset Caster Bushes – BMW F20 M135i / M140i

Transform the front-end response of your BMW F20 M135i or M140i with Suspension Secrets Front Offset Caster Bushes.

The standard front lower control arm bushes use soft rubber, which can flex significantly under cornering and braking loads. This movement can contribute to vague steering, understeer and reduced stability when braking hard.

Suspension Secrets Front Offset Caster Bushes replace this compliant arrangement with a solid, rose-jointed solution that reduces unwanted movement while also allowing the front suspension geometry to be improved through increased positive caster.

Why Upgrade to Front Offset Caster Bushes?

These bushes are designed to improve both front axle precision and geometry control.

Potential benefits include:

• Increased positive caster
• Improved steering feel
• Increased cornering grip
• Better braking stability
• More accurate steering
• Reduced unwanted suspension deflection
• Greater caster control
• Improved wheel positioning with adjustable top mounts

Key Features

• Designed for BMW F20 M135i and M140i
• Solid front control arm bush design
• Offset rose-joint arrangement
• Increases positive caster
• Improves steering accuracy
• Improves braking stability
• Helps increase front-end grip
• Reduces bush deflection
• Useful with caster-adjustable top mounts
• Helps reposition the front wheel within the arch

The Problem With the Factory Bushes

The OEM front lower control arm bushes are designed primarily around comfort and refinement.

Their soft rubber construction allows movement under load.

During harder driving, this can lead to:

• Vague steering
• Reduced front-end precision
• Increased understeer
• Geometry changes
• Nervousness under heavy braking

Reducing this unwanted compliance helps the suspension maintain a more consistent position.

Solid Bush Design

Unlike the factory rubber bushes, the Suspension Secrets design does not rely on soft rubber compliance.

This helps reduce movement between the control arm and chassis, resulting in a more direct and predictable front axle.

Potential benefits include:

• Better steering consistency
• Sharper response
• Improved braking confidence
• Greater chassis precision

Increased Positive Caster

The offset rose joints are designed to increase positive caster.

Caster influences how the front wheels move and gain camber as steering angle increases.

More positive caster can provide:

• Stronger steering self-centering
• Improved steering feel
• Increased dynamic camber gain
• Better front-end grip during cornering

Dynamic Camber Gain

As steering angle increases, positive caster can generate additional negative camber on the outside front wheel.

This helps keep the tyre in a more favourable position during cornering.

Potential benefits include:

• Improved tyre contact
• Increased front-end grip
• Reduced understeer
• Better cornering confidence

Improved Steering Feel

Reducing bush deflection and increasing caster can make the steering feel more communicative.

This can result in:

• Greater front-end feedback
• More accurate steering response
• Improved confidence at speed
• More predictable turn-in

Improved Braking Stability

The factory bushes can deform under heavy braking, allowing the front suspension geometry to move.

The solid bush design reduces this movement, helping the front wheels remain more stable under braking loads.

This can improve:

• Straight-line stability
• Braking confidence
• Steering consistency under deceleration

Useful With Adjustable Top Mounts

These bushes are particularly useful on cars already fitted with caster-adjustable suspension top mounts.

Running aggressive caster settings at the top mount can move the front wheel away from the centre of the wheel arch.

This can create clearance problems during steering lock.

Helps Prevent Wheel Arch Liner Contact

When maximum caster is added through adjustable top mounts, the front wheel can move far enough within the wheel arch to contact the inner liner.

The offset caster bush can be used to help reposition the wheel while retaining the desired top-mount caster setting.

This can help prevent:

• Wheel arch liner rubbing
• Tyre contact
• Clearance issues at steering lock

Greater Caster Control

Using offset bushes alongside adjustable top mounts gives much greater freedom when configuring front suspension geometry.

This is especially useful for:

• Fast-road builds
• Clubsport cars
• Trackday cars
• Cars running aggressive front geometry
• Performance tyre setups

Ideal for Track-Focused Geometry

The upgrade is particularly useful where maximum front-end grip and geometry control are priorities.

It works well alongside:

• Camber/caster plates
• Coilovers
• Adjustable drop links
• Performance tyres
• Uprated anti-roll bars
• Full geometry setups

NVH Considerations

Because these bushes use a solid, rose-jointed design rather than compliant factory rubber, some increase in noise, vibration and harshness may be expected.

This is a more performance-focused upgrade intended for drivers prioritising steering precision and suspension control over factory levels of refinement.

Professional Installation Recommended

Professional installation is recommended.

After fitting, the car should receive:

• Suspension inspection
• Steering clearance checks
• Wheel alignment
• Caster setup
• Camber setup
• Toe adjustment

Geometry Setup Essential

A professional geometry setup is strongly recommended after installation.

Caster, camber and toe should be configured together to suit:

• Road or track use
• Ride height
• Tyre choice
• Top-mount settings
• Desired handling balance

Vehicle Fitment

BMW 1 Series F20

Compatible models:

• BMW M135i F20
• BMW M140i F20

What's Included?

Each kit includes:

• 1 pair Suspension Secrets Front Offset Caster Bushes

Explore More BMW F20 Suspension

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