How is the SPL RKB F3X different from the SPL RLCB E9X rear lower control arm knuckle bushing?

These are two separate bushings at two different locations in the rear suspension. The SPL RLCB E9X (BMW OEM 33326775552 and 33326756249) targets the connection between the rear lower control arm and the rear knuckle, and fits the E8X, E9X, F2X, F3X, F8X, and G8X platform range. The SPL RKB F3X (BMW OEM 33326792551) targets the connection between the rear traction arm and the rear knuckle, and is specific to the F2X and F3X platforms. Both are separate bushing positions and separate purchases; a complete F2X/F3X rear bushing conversion benefits from addressing both locations.

What is the rear traction arm, and why does this bushing matter?

The rear traction arm on the F2X and F3X is one of the lower rear suspension links that controls the longitudinal position of the rear wheel and contributes to stability under acceleration, braking, and cornering. The traction arm connects to the rear knuckle through a rubber bushing that deflects under load, allowing the traction arm to move slightly relative to the knuckle. This movement changes the rear wheel's position dynamically; degrading rear suspension precision under the conditions where consistency matters most. Replacing the rubber with a spherical bearing eliminates that deflection and holds the traction arm in position under all load conditions.

What OEM part number does the SPL RKB F3X replace?

The SPL RKB F3X replaces BMW OEM part number 33326792551, which is the factory rubber traction arm knuckle bushing used across F2X and F3X 1 Series, 2 Series, 3 Series, and 4 Series models from 2010 to 2019.

Why does SPL use the largest possible FK bearing in this location?

A larger bearing spreads the same load over more contact surface area, reducing the stress per unit area on both the bearing and the housing. Lower specific loading results in slower wear, better longevity, and cooler operating temperatures under sustained use. SPL specifically calls out the bearing sizing decision because it is a deliberate engineering choice to maximize long-term performance and minimize NVH rather than designing to a minimum specification.

Should this bushing be replaced at the same time as the rear lower control arm knuckle bushing and other rear bushings?

Yes. Shops that perform complete F2X and F3X rear suspension bushing conversions address all rubber bushing positions simultaneously. Replacing some positions while leaving factory rubber in others leaves deflection points that partially offset the gains from the upgraded positions. The traction arm knuckle bushing and the lower control arm knuckle bushing (SPL RLCB E9X) are two of the F2X/F3X-specific positions that should both be included in a complete rear bushing rebuild.

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Description

SPL Parts Rear Traction Arm Knuckle Bushing for F2x / F3x BMW 1, 2, 3, and 4 Series

The rear suspension on the BMW F2x and F3x connects to the rear knuckle through a number of separate bushing positions; each one a potential deflection point under hard cornering, braking, and acceleration. The traction arm knuckle bushing is the rubber interface between the rear traction arm and the rear knuckle itself, and it is one of the positions that gets overlooked in builds that address trailing arm bushings and toe/camber arm bushings without going the full distance. Under high lateral and longitudinal loads, rubber at this location compresses and allows the traction arm to move relative to the knuckle; the wheel position shifts, geometry changes dynamically, and the rear suspension behaves less precisely than the alignment targeted. The SPL Parts RKB F3X replaces that rubber with the largest FK Teflon-lined spherical bearing that will physically fit in this location. The decision to use the largest possible bearing is a deliberate one; a larger bearing distributes the same load over more surface area, reduces specific loading on the bearing and housing, and provides greater longevity and lower NVH than a smaller bearing carrying the same forces through a tighter interface. The 6061-T6 aluminum housing is CNC-machined to +/- .001-inch tolerance, the same precision standard SPL applies across their full bushing lineup; this ensures the bearing seats accurately in the knuckle and holds dimensional stability through thermal cycling and sustained suspension loading.

Features

Replaces factory rear traction arm knuckle rubber bushing with a Teflon-lined FK spherical bearing; eliminates deflection at the traction arm-to-knuckle connection under heavy cornering, braking, and acceleration loads
Largest possible FK bearing used at this location; maximizes contact area, reduces specific loading, improves longevity, and lowers NVH compared to a smaller bearing at the same load
CNC-machined 6061-T6 aluminum bearing housing; machined to +/- .001-inch tolerance for accurate fitment and dimensional stability
Teflon liner self-lubricating; no maintenance required; smooth, low-friction articulation through the full suspension range without binding

Specifications

Material: CNC-machined billet aluminum or PTFE-lined spherical bearing (per part)
Replaces: OEM rubber bushing
Adjustment: None (solid replacement)
Origin: Made in the USA

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

SPL components are made-to-order in the USA; build time will be confirmed at the time of order

Frequently Asked Questions

How is the SPL RKB F3X different from the SPL RLCB E9X rear lower control arm knuckle bushing? These are two separate bushings at two different locations in the rear suspension. The SPL RLCB E9X (BMW OEM 33326775552 and 33326756249) targets the connection between the rear lower control arm and the rear knuckle, and fits the E8x, E9x, F2x, F3x, F8x, and G8x platform range. The SPL RKB F3X (BMW OEM 33326792551) targets the connection between the rear traction arm and the rear knuckle, and is specific to the F2x and F3x platforms. Both are separate bushing positions and separate purchases; a complete F2x / F3x rear bushing conversion benefits from addressing both locations.
What is the rear traction arm, and why does this bushing matter? The rear traction arm on the F2x and F3x is one of the lower rear suspension links that controls the longitudinal position of the rear wheel and contributes to stability under acceleration, braking, and cornering. The traction arm connects to the rear knuckle through a rubber bushing that deflects under load, allowing the traction arm to move slightly relative to the knuckle. This movement changes the rear wheel’s position dynamically; degrading rear suspension precision under the conditions where consistency matters most. Replacing the rubber with a spherical bearing eliminates that deflection and holds the traction arm in position under all load conditions.
What OEM part number does the SPL RKB F3X replace? The SPL RKB F3X replaces BMW OEM part number 33326792551, which is the factory rubber traction arm knuckle bushing used across F2x and F3x 1 Series, 2 Series, 3 Series, and 4 Series models from 2010 to 2019.
Why does SPL use the largest possible FK bearing in this location? A larger bearing spreads the same load over more contact surface area, reducing the stress per unit area on both the bearing and the housing. Lower specific loading results in slower wear, better longevity, and cooler operating temperatures under sustained use. SPL specifically calls out the bearing sizing decision because it is a deliberate engineering choice to maximize long-term performance and minimize NVH rather than designing to a minimum specification.
Should this bushing be replaced at the same time as the rear lower control arm knuckle bushing and other rear bushings? Yes. Shops that perform complete F2x and F3x rear suspension bushing conversions address all rubber bushing positions simultaneously. Replacing some positions while leaving factory rubber in others leaves deflection points that partially offset the gains from the upgraded positions. The traction arm knuckle bushing and the lower control arm knuckle bushing (SPL RLCB E9X) are two of the F2X/F3X-specific positions that should both be included in a complete rear bushing rebuild.

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 Rear Traction Arm Knuckle Bushing for F2x / F3x BMW 1, 2, 3, and 4 Series [SPLRKBF3X]

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SPL Parts Rear Traction Arm Knuckle Bushing for F2x / F3x BMW 1, 2, 3, and 4 Series

Features

Specifications

Applications

Notes

Frequently Asked Questions

About SPL Parts

Reviews