Is there a separate version of these bushings for xDrive BMW F2X and F3X models?

Yes. This listing, part number SPL CRB F3X, fits rear-wheel-drive F2X and F3X models only. SPL Parts produces a separate caster rod bushing set specifically for F2X and F3X xDrive AWD variants. Confirm your drivetrain configuration before ordering; the two parts are not interchangeable.

What does replacing the factory rubber caster rod bushings actually improve on the F2X and F3X?

The factory rubber bushings deflect under braking and lateral load, allowing the front geometry to shift away from its set position when it matters most. Replacing them with FK spherical bearings keeps the caster rod at its set position under all load conditions. The most noticeable improvements are more consistent and stable braking, sharper turn-in with more accurate steering feedback, and front suspension behavior that behaves the same at the limit as it does in normal driving.

How much caster adjustment do the SPL CRB F3X bushings provide, and why does it matter?

The CNC-machined aluminum offset spacers provide up to +/- 4 degrees of caster adjustment. Most F2X and F3X models arrive from the factory with less front caster than is optimal for track use. More caster improves steering return-to-center feel, high-speed stability, and front grip balance at the limit. The adjustment range also allows left-to-right caster to be equalized, which is important on cars that have been lowered or have uneven front geometry from use.

Will these bushings increase road noise or harshness on my daily-driven BMW?

Some increase in NVH is possible. Replacing the rubber with a spherical bearing removes one of the front suspension's compliant elements, which can result in more transmitted road noise, particularly on rough surfaces. If these are installed alongside SPL front lower control arms, which also replace rubber with spherical bearings, all compliant front bushings are eliminated and NVH increases more noticeably. SPL describes this as road noise and impact harshness rather than a jarring or uncomfortable force. For primarily track-use vehicles, this is generally a non-issue.

What BMW part number do the SPL CRB F3X bushings replace?

The SPL Parts CRB F3X replaces BMW part number 31126855743, which is the factory rubber caster rod bushing used across F20, F21, F22, F23, F30, F31, F32, F33, F34, F35, and F36 RWD models.

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Description

SPL Parts Adjustable Front Caster Rod Monoball Bushings for F2x / F3x BMW 1, 2, 3, and 4 Series (xDrive AWD)

SPL FKS Series Adjustable Front Caster Rod Bushings (CRB) for the BMW F2x / F3x xDrive (AWD) replace the soft OEM rubber bushings with low-friction articulating FK USA spherical bearings, eliminating bushing deflection and reducing friction. Massive 1″ FK racing bearings with self-lubricating Teflon liners maintain optimum suspension geometry under braking and cornering load, while integrated caster adjustment lets you dial in exactly the angle you want.

Features

Purpose-built for BMW F2x and F3x xDrive AWD variants; uses a different bearing geometry than the RWD equivalent
Replaces factory rubber caster rod bushings with low-friction, articulating FK Racing 1-inch spherical bearings; eliminates bushing deflection under braking and cornering load
Self-lubricating Teflon-lined bearings require no greasing and maintain performance durability through sustained use
CNC-machined 6061-T6 aluminum offset bearing spacers provide +/- 4 degrees of caster adjustment
6061-T6 aluminum bearing housing with outer knurl for precise press-fit into the OEM caster rod arm
Maintains optimum front suspension geometry under load; improves braking stability and steering feedback
Sold as a pair; includes left and right bushings with hardware
Made in the USA

Specifications

Material: Billet aluminum mounts
Bushings: 1″ FK USA spherical bearings, Teflon-lined
Adjustment: Caster — wide range

Applications

BMW 116d: F20, F21 | 2012-2019
BMW 118d: F20, F21 | 2012-2019
BMW 120d: F20, F21 | 2012-2019
BMW 125d: F20, F21 | 2012-2019
BMW 128ti: F20, F21 | 2019-2019
BMW 114i: F20, F21 | 2012-2019
BMW 116i: F20, F21 | 2012-2019
BMW 118i: F20, F21 | 2012-2019
BMW 120i: F20, F21 | 2012-2019
BMW 125i: F20, F21 | 2012-2019
BMW 135i: F20, F21 | 2012-2016
BMW 220d: F22, F23 | 2014-2021
BMW 225d: F22, F23 | 2014-2021
BMW 220i: F22, F23 | 2014-2021
BMW 228i: F22, F23 | 2014-2016
BMW 230i: F22, F23 | 2016-2021
BMW 240i: F22, F23 | 2016-2021
BMW 316d: F30, F31 | 2012-2019
BMW 318d: F30, F31 | 2012-2019
BMW 320d: F30, F31 | 2012-2019
BMW 325d: F30, F31 | 2012-2019
BMW 330d: F30, F31 | 2012-2019
BMW 335d: F30, F31 | 2012-2019
BMW 330e: F30, F31 | 2015-2019
BMW 316i: F30, F31 | 2012-2019
BMW 318i: F30, F31 | 2012-2019
BMW 320i: F30, F31 | 2012-2019
BMW 328i: F30, F31 | 2012-2016
BMW 330i: F30, F31 | 2016-2019
BMW 335i: F30, F31 | 2012-2015
BMW 340i: F30, F31 | 2015-2019
BMW 420d: F32, F33, F36 | 2014-2020
BMW 425d: F32, F33, F36 | 2014-2020
BMW 430d: F32, F33, F36 | 2014-2020
BMW 435d: F32, F33, F36 | 2014-2020
BMW 420i: F32, F33, F36 | 2014-2020
BMW 428i: F32, F33, F36 | 2014-2016
BMW 430i: F32, F33, F36 | 2016-2020
BMW 435i: F32, F33, F36 | 2014-2016
BMW 440i: F32, F33, F36 | 2016-2020
BMW M135i: F20, F21 | 2012-2016
BMW M140i: F20, F21 | 2016-2019
BMW M235i: F22, F23 | 2014-2016
BMW M240i: F22, F23 | 2016-2021
BMW M340i: F30, F31 | 2019-2019

Notes

Installation Instructions
OEM arms not included
Only compatible with xDrive/AWD vehicles
SPL components are made-to-order in the USA; build time will be confirmed at the time of order.

Frequently Asked Questions

What is the difference between the SPL CRB F3X and the SPL CRB F3iX? These are two distinct parts for two different drivetrains. The SPL CRB F3X fits RWD F2xand F3x models and replaces BMW part number 31126855743. The SPL CRB F3iX fits xDrive AWD F2x and F3x models and replaces BMW part number 31126854729. The two BMW part numbers are different because the xDrive caster rod uses a different bushing geometry at the arm. Ordering the wrong part will result in a fitment issue; confirm your drivetrain before ordering.
How do I confirm whether my F3X uses the xDrive or RWD caster rod bushing? Confirm your drivetrain in your car’s VIN, the door jamb sticker, or the BMW order code sheet. Any F3x or F2x model with xDrive in its name or spec sheet uses the AWD caster rod bushing replaced by the CRB F3iX. Models without xDrive designation are RWD and use the CRB F3X.
What does replacing the caster rod bushings improve on an xDrive BMW? Factory rubber caster rod bushings deflect under braking and cornering loads, shifting the front geometry away from its aligned position. On an xDrive model, front geometry consistency is equally important for brake stability and turn-in response; the AWD system does not compensate for front suspension deflection. Replacing the rubber with FK spherical bearings keeps caster and geometry set under all load conditions, improving braking stability, turn-in sharpness, and steering feedback quality.
How much caster adjustment does the SPL CRB F3iX provide? The CNC-machined 6061-T6 aluminum offset bearing spacers provide up to +/- 4 degrees of caster adjustment. This range allows alignment technicians to add caster beyond the factory eccentric bolt range or to correct left-to-right caster imbalance, which is common on lowered or track-aligned cars.
Are the OEM caster rod arms included with the SPL CRB F3iX? No. This listing is for the replacement bushings only. The OEM caster rod arms remain in the car; the SPL bushings replace the rubber inserts within the existing arms. OEM part number 31126854729 is the factory bushing being replaced.

About SPL Parts

SPL Parts is a USA-based manufacturer of high-performance suspension components engineered for both professional racing and demanding street applications. Built on the core principles of strength, lightweight construction, low friction, and precision, SPL Parts products deliver the adjustability and alignment performance required by top race teams and discerning enthusiasts alike. Every component is produced using USA-sourced, certified materials and machined by experienced local shops to exacting tolerances. Professional TIG welders ensure maximum weld integrity, while each part is hand-fitted and treated with anti-seize and 3M internal panel coating for lasting protection. SPL Parts conducts all research and development in-house, allowing the team to leverage firsthand product knowledge and deliver unmatched customer support. Their suspension components feature innovative adjuster designs for quicker, more precise alignments, and utilize spherical bearings with Teflon liners that are self-cleaning, self-lubricating, and built for long service life. From concept to assembly, SPL Parts is made with pride in the USA by skilled machinists and welders who are committed to quality, innovation, and performance.

Additional Information

The Bulletproof Automotive website contains many thousands of products purchased in multiple different currencies. All of the prices are entered manually and accurately at the time of entry. Due to the consistently fluctuating international exchange rates, at times prices may not be able to be honored at their original intended rate. We apologize for any inconvenience this may cause, unfortunately our website is unable to compensate dynamically for what can at times be volatile changes in the cost of items due to currency values fluctuating, changes in prices from suppliers, changes in shipping and import duties, and other factors. Rest assured that any order you place on line will be at zero risk to you in this area. If in the event your order cannot be fulfilled at the original intended website price we will offer you a 100% refund, no questions asked. We will continue to do our best to maintain updated prices and we will always continue to offer our price match guarantees as well to ensure our prices are always the best for you. In short, prices may change without notice. It is always advised to give us a call prior to placing your order online to confirm availability and to confirm current pricing.

Shipping Policy

Items that are in stock in the US, either at Bulletproof’s warehouse or at a supplier’s warehouse, are generally delivered within 7-10 days. Special order items from overseas take considerably longer. As a courtesy Bulletproof offers delivery estimates to our customers which take into consideration manufacturer availability and shipping schedule. These estimates represent our best guess based on previous orders from the manufacturer and do not in any way imply a guaranteed delivery window. Many manufacturers work in a “just in time” inventory system and often take 2-20+ weeks to produce an item once an order is submitted. All deliverable items are then sent to our Japanese warehouse. Bulletproof ships a minimum of one full ocean freight container every month from Japan, oftentimes more than one a month. Ocean freight takes an average of 4 weeks. Typically it breaks down to one week in Japan for paperwork and customs, two weeks by boat and one week in US customs/clearance. Due to the wide number of variables between manufacturer and shipping schedules, delivery estimates are simply just that – estimates. We attempt to estimate conservatively and we usually deliver faster than our estimates suggest. It is not Bulletproof’s policy to guarantee delivery time of any special order item, this is impossible for us to do. By ordering you acknowledge that there is no required delivery ETA and an order may not be canceled or altered due to manufacturing or shipping delays, all ETA’s are provided as a best guess only. Please review the full Terms & Conditions here.

BP Pricing Difference

We do pricing a little differently on our JDM brands and we believe in making things simple and clear. No hidden fees or surcharges. Every price you see includes the shipping cost to our office in Los Angeles, California and all the associated taxes/duties/fees for bringing the products into the US. The only shipping you ever pay is from our facility in the US to your location. Be wary of resellers that don’t include the cost of international shipping in their pricing on JDM parts. While we believe we’ll always have the lowest all-in price on JDM products, we offer a price match guarantee for all authentic parts purchased from authorized dealers as well. For many international customers, it’s much more affordable to ship from the USA than from Japan directly, as the air freight and ocean freight costs are typically much less. However, for customers looking to ship directly from Japan outside of North America, or domestically in Japan, we can provide pricing specifically for that scenario. Please do not hesitate to contact us with any pricing questions or concerns. Please email us at sales@bulletproofautomotive.com with any inquiries.

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SPL Parts Adjustable Front Caster Rod Monoball Bushings for F2x / F3x BMW 1, 2, 3, and 4 Series [SPLCRBF3X]

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SPL Parts Adjustable Front Caster Rod Monoball Bushings for F2x / F3x BMW 1, 2, 3, and 4 Series (xDrive AWD) [SPLCRBF3IX]

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SPL Parts Adjustable Front Caster Rod Monoball Bushings for F2x / F3x BMW 1, 2, 3, and 4 Series (xDrive AWD)

Features

Specifications

Applications

Notes

Frequently Asked Questions

About SPL Parts

Reviews