SPL Parts Adjustable Front Caster Rod Monoball Bushings for BMW 2 Series 3 Series 4 Series (F2X/F3X) - Front Control Arm Spherical Bearings, FKS Series FK 1in, +/- 4° Caster (CRB F3X)

Unlock razor sharp steering feel and rock solid front-end stability on your BMW F2X and F3X with this SPL caster correction kit. This premium monoball conversion replaces the factory rubber rear bush on the front lower wishbone with a motorsport-grade assembly for instant turn-in, repeatable geometry and confidence under heavy braking on fast road and track day cars.

Engineered around huge 1 inch FK Racing Bearings with self lubricating PTFE liners housed in precision CNC machined 6061-T6 aluminium bodies, this upgrade eliminates flex and slop you get from the standard thrust arm bush. Adjustable offset spacers provide ± 4° caster range so you can dial in aggressive alignment for grip and stability without sacrificing tyre wear when set up correctly.

Real world results: We have fitted these at MJ Modifications to multiple customer F2X and F3X builds. Feedback has been consistently excellent, with owners reporting crisper steering response, improved straight line stability, better mid-corner feedback and more confidence on the brakes lap after lap.

Key benefits

• Wide caster adjustment window of ± 4° to fine tune front-end geometry
• Massive FK 1 inch spherical bearing for precision and durability
• PTFE lined, low friction articulation for smooth operation and long life
• 6061-T6 aluminium housings with offset spacers for strength and reduced weight
• Sharper turn-in, consistent alignment under load and reduced wander at speed
• Sold as a pair, made in the USA

What is included

• Pair of SPL front tension strut monoball assemblies
• 6061-T6 aluminium bearing housings with outer knurl
• Offset aluminium spacers for ± 4° caster adjustment
• FK 1 inch bearings with self lubricating PTFE liners

Vehicle fitment

BMW F2X 2 Series and F3X 3 Series and 4 Series platforms.

Note: Not compatible with xDrive or AWD models. Uses the original arms which are not included.

Part number

SPL CRB F3X

Why upgrade this location

The rear bush on the front lower arm takes a beating under braking and cornering. The OE rubber deforms, causing geometry change, vague steering and inconsistent pedal feel. This monoball conversion stabilises the radius arm, locks in alignment and gives immediate feedback through the wheel without excessive NVH when set up correctly.

Installation and setup

Professional installation is recommended. An alignment is advised after fitting to take advantage of the caster range and to set toe accordingly.

Fitting available: MJ Modifications, Warwickshire. Request a quote at info@mjmodifications.co.uk.

Brand

Manufactured by: SPL Parts

Search phrases customers use

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