Why does the F8X M3 and M4 specifically need rear upper arm replacements compared to other BMWs?

The stock BMW F8X setup has an aggressive camber curve through bump travel, which is very apparent on lowered cars. Excess negative camber causes premature tire wear on the inside edge and reduced traction on acceleration, while too little camber limits rear grip while cornering. The F8X's rear suspension geometry moves through this aggressive camber curve faster than less performance-oriented platforms, which makes the factory eccentric adjustment range insufficient for any meaningful lowering or track alignment work. The SPL RUA F8X provides the wide adjustment range needed to counter that camber curve and hold the tire at the correct angle under load.

What arms are included in the SPL RUA F8X kit?

The SPL kit replaces the factory links commonly referred to as the rear wishbone and rear guide links; four arms total for one car. The rear wishbone governs rear camber; the rear guide link governs the longitudinal position of the rear wheel. Both positions are replaced simultaneously so the full upper rear suspension operates at the same construction standard.

Does the SPL RUA F8X fit the G8X M3 and M4?

No. The SPL RUA F8X is engineered specifically for the F8X generation (2014-2021 F80 M3, F82/F83 M4, F87 M2). The current G8X generation uses a different rear subframe and knuckle geometry. A separate SPL RUA G8X is available for G8X models; the two kits are not interchangeable.

How does replacing the rear upper arms eliminate the need to chase alignment changes on track?

The factory rubber bushings in the rear wishbone and guide links flex every time the car brakes, corners, or applies power. That movement lets the wheel and tire walk around in ways that change the alignment setting mid-session, sending the driver chasing damper and setup changes that may have been correct in the first place. The FK spherical bearings hold the arm positions precisely under all load conditions, so the alignment set at the rack is the alignment the car runs throughout the session.

Are replacement rod ends available for the SPL RUA F8X?

Yes. SPL Parts offers replacement rod ends for the RUA F8X in both left and right hand thread. Contact SPL Parts directly or use the links on the SPL Parts product page for the correct replacement.

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Description

SPL Parts Adjustable Rear Upper Control Arms for F8x BMW M2 / M3 / M4

The BMW F8x M3 and M4 have an aggressive rear camber curve through bump travel. On a stock car at factory ride height, this is managed within acceptable limits. Lower the car; even modestly; and that camber curve moves fast. The inner edges of the rear tires start carrying more load than they should, wear accelerates unevenly, and the rear grip balance shifts in ways that neither springs, dampers, nor alignment within the factory eccentric range can fully correct. In the experience of shops that build F8x M cars specifically for track use, these rear upper arms are effectively required hardware to reach the aggressive rear camber targets these cars like to run on track. The SPL Parts RUA F8X replaces both the rear wishbone (camber arm) and the rear guide link (traction arm); four arms total for one car; with gun-drilled 2024 aluminum links that are black anodized for corrosion resistance. The camber arm uses SPL’s 360-degree rotating clamp with 6061-T6 aluminum clamp body and blue anodized titanium socket head cap screws to lock the camber setting without jam nuts; one allen key, one step, trackside-adjustable. The wide adjustment range covers proper track alignment specifications or dials back to street use without fighting factory limits.

Features

Complete four-arm rear upper kit; replaces both the rear wishbone (camber arm) and rear guide link (traction arm) on both rear corners
Wide camber adjustment range; covers aggressive track targets as well as street alignment specifications
Gun-drilled 2024 aluminum links; black anodized for corrosion resistance; gun-drilling reduces unsprung weight
SPL exclusive 360-degree rotating clamp with 6061-T6 aluminum clamp body and blue anodized titanium socket head cap screws; locks camber setting without jam nuts; single allen key adjustment
FK spherical rod ends manufactured in Connecticut; self-lubricating, self-cleaning Teflon liner chemically bonded to inner race; eliminates rubber bushing deflection under all load conditions
Teflon liner operating temperature range: -65°F to 325°F; no maintenance required
Tapered stainless steel knuckle mount spacers included for precise rear knuckle fitment

Specifications

Body Material: 2024-T351 aluminum (gun-drilled, black anodized)
Bushings: PTFE-lined FK USA spherical bearings
Adjustment: Camber, track width
Origin: Made in the USA

Applications

BMW M2: F87 | 2016-2021
BMW M3: F80 | 2014-2018
BMW M4: F82, F83 | 2014-2020

Notes

Installation Instructions
Replacement rod ends available from SPL Parts in left and right hand thread, please contact us
SPL components are made-to-order in the USA; build time will be confirmed at the time of order.

Frequently Asked Questions

Why does the F8x M3 and M4 specifically need rear upper arm replacements compared to other BMWs? The stock BMW F8x setup has an aggressive camber curve through bump travel, which is very apparent on lowered cars. Excess negative camber causes premature tire wear on the inside edge and reduced traction on acceleration, while too little camber limits rear grip while cornering. The F8x’s rear suspension geometry moves through this aggressive camber curve faster than less performance-oriented platforms, which makes the factory eccentric adjustment range insufficient for any meaningful lowering or track alignment work. The SPL RUA F8X provides the wide adjustment range needed to counter that camber curve and hold the tire at the correct angle under load.
What arms are included in the SPL RUA F8X kit? The SPL kit replaces the factory links commonly referred to as the rear wishbone and rear guide links; four arms total for one car. The rear wishbone governs rear camber; the rear guide link governs the longitudinal position of the rear wheel. Both positions are replaced simultaneously so the full upper rear suspension operates at the same construction standard.
Does the SPL RUA F8X fit the G8X M3 and M4? No. The SPL RUA F8X is engineered specifically for the F8x generation. The current G8x generation uses a different rear subframe and knuckle geometry. A separate SPL RUA G8X is available for G8x models; the two kits are not interchangeable.
How does replacing the rear upper arms eliminate the need to chase alignment changes on track? The factory rubber bushings in the rear wishbone and guide links flex every time the car brakes, corners, or applies power. That movement lets the wheel and tire walk around in ways that change the alignment setting mid-session, sending the driver chasing damper and setup changes that may have been correct in the first place. The FK spherical bearings hold the arm positions precisely under all load conditions, so the alignment set at the rack is the alignment the car runs throughout the session.
Are replacement rod ends available for the SPL RUA F8X? Yes. SPL Parts offers replacement rod ends for the RUA F8X in both left and right hand thread. Contact Bulletproof sales team.

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 Rear Upper Control Arms for F8x BMW M2 / M3 / M4 [SPLRUAF8X]

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SPL Parts Adjustable Rear Upper Control Arms for F8x BMW M2 / M3 / M4

Features

Specifications

Applications

Notes

Frequently Asked Questions

About SPL Parts

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