What is the difference between the SPL CRBN F3iX and the adjustable SPL CRB F3iX?

The CRBN F3iX is the non-adjustable version. It replaces the factory rubber with an FK spherical bearing, eliminating bushing deflection while keeping caster at its current set position. The adjustable CRB F3iX adds CNC-machined offset aluminum spacers that provide up to +/- 4 degrees of caster adjustment. If caster is already correct or handled elsewhere, the CRBN F3iX is the more focused and typically lower-cost choice. If caster adjustment is needed at the bushing, choose the CRB F3iX.

Does the SPL CRBN F3iX fit RWD F2X and F3X models?

No. The CRBN F3iX is engineered specifically for xDrive AWD F2X and F3X models and replaces BMW part number 31126854729, which is xDrive-specific. The RWD equivalent is the SPL CRBN F3X, a separate part that replaces BMW part number 31126855743. The two parts are not interchangeable; confirm your drivetrain before ordering.

Why does the xDrive version use a different BMW part number than the RWD version?

The caster rod on xDrive models uses a different OEM bushing specification than the RWD version due to differences in the front subframe and caster rod geometry between the two drivetrains. BMW part number 31126854729 is the xDrive bushing; 31126855743 is the RWD bushing. SPL Parts engineers each replacement to match the OEM geometry for each drivetrain precisely.

What warranty does SPL Parts provide on the CRBN F3iX?

SPL Parts backs this product with a 10-year/100,000-mile warranty against defects in material and workmanship. If the product fails to meet specifications within that period, SPL Parts will repair, replace, or make appropriate adjustment at their discretion.

Are OEM caster rod arms included?

No. The CRBN F3iX replaces the rubber bushing inserts within the existing OEM caster rod arms. The arms themselves remain in the car and are not included with this purchase. Replaces BMW part number 31126854729.

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BP PRICING DIFFERENCE

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Description

SPL Parts Non-Adjustable Front Caster Rod Bushings for F2x BMW 2 Series and F3x 3 / 4 Series

There is a version of your F2x or F3x that exists under the factory rubber bushing compliance, and it handles better than what you’re currently experiencing. The front geometry on these platforms is well thought out from the factory; the problem is that rubber caster rod bushings don’t hold it there under load. When the caster rod bushing compresses and deflects under braking or cornering force, the geometry shifts in real time, introducing a layer of imprecision between driver input and tire response that rubber-bushed cars simply live with. The SPL Parts CRBN F3x addresses that directly.

Features

Eliminates factory rubber caster rod bushing deflection with 1-inch FK Racing spherical bearings using self-lubricating Teflon liners; no greasing required
Non-adjustable; no offset spacers; caster geometry remains at its current set position
6061-T6 aluminum bearing housing with outer knurl; presses into the OEM caster rod arm with no modification required
Holds front geometry at its set position under braking and cornering load; improves braking consistency, turn-in response, and steering feedback
All materials sourced from American suppliers; CNC machining and TIG welding performed locally by SPL Parts to tight tolerance specifications
Sold as a pair; left and right bushings with hardware included
Backed by SPL Parts’ 10-year/100,000-mile warranty against defects in material and workmanship
Made in the USA

Specifications

Material: CNC-machined billet aluminum
Adjustment: None — fixed geometry

Applications

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 330d: F30, F31 | 2012-2019
BMW 325d: F30, F31 | 2012-2019
BMW 335d: F30, F31 | 2012-2019
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 330e: F30, F31 | 2015-2019
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 M235i: F22, F23 | 2014-2016
BMW M240i: F22, F23 | 2016-2021
BMW M340i: F30, F31 | 2019-2019

Complete the Kit

Notes

Installation Instructions
Not compatible with xDrive/AWD models
OEM arms not included
For adjustable bushings click here
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 CRBN F3X and the adjustable SPL CRB F3X? The CRBN F3X is the non-adjustable version. It replaces the factory rubber with an FK spherical bearing, eliminating caster rod deflection while keeping caster at its current aligned position. The adjustable CRB F3X adds CNC-machined offset aluminum spacers providing up to +/- 4 degrees of caster adjustment. If the alignment is already correct or being adjusted via SPL tension rods or another method, the CRBN F3X eliminates the deflection problem without changing anything else. If caster adjustment is needed at the bushing itself, the CRB F3X is the right choice.
Does the SPL CRBN F3X fit xDrive or AWD F2x and F3x models? No. The CRBN F3X is designed exclusively for RWD F2x and F3x models and replaces BMW part number 31126855743, which is RWD-specific. The xDrive equivalent is the SPL CRBN F3iX, which replaces BMW part number 31126854729. The two parts are not interchangeable; confirm your drivetrain configuration before ordering.
When is the non-adjustable version the better choice over the adjustable version? The CRBN F3X is the better choice in three situations: when the current caster setting is already correct for your alignment target; when caster adjustment is being handled by another component such as SPL tension rods; or when the goal is simply eliminating rubber deflection without introducing any new geometry changes. It is also typically priced lower than the adjustable version, making it the more efficient choice for builds that don’t need caster adjustment at this point in the suspension.
What warranty does SPL Parts provide on the CRBN F3X? SPL Parts backs this product with a 10-year/100,000-mile warranty against defects in material and workmanship from the date of purchase. If a product fails to meet specifications within that period, SPL Parts will repair, replace, or make appropriate adjustment at their discretion.
Are OEM caster rod arms included? No. The CRBN F3X replaces the rubber bushing inserts within the existing OEM caster rod arms. The arms themselves stay in the car and are not included with this purchase. Replaces BMW part number 31126855743.

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 Non-Adjustable Front Caster Rod Bushings for F2x BMW 2 Series and F3x 3 / 4 Series (xDrive AWD) [SPLCRBNF3IX]

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SPL Parts Non-Adjustable Front Caster Rod Bushings for F2x BMW 2 Series and F3x 3 / 4 Series [SPLCRBNF3X]

Guaranteed Safe Checkout

SPL Parts Non-Adjustable Front Caster Rod Bushings for F2x BMW 2 Series and F3x 3 / 4 Series

Features

Specifications

Applications

Complete the Kit

Notes

Frequently Asked Questions

About SPL Parts

Reviews