SPL Rear Upper Arms – BMW M3 / M4 (G8x)

OVERVIEW

SPL Parts adjustable Rear Upper Arms (RUA) for the BMW G8X are essential for maintaining proper rear camber and reducing tire wear on the street and on track. The stock BMW setup has an aggressive camber curve through bump travel, which becomes very apparent on lowered cars: excess negative camber wears the inside edge of the tire prematurely and reduces traction under acceleration, while too little camber limits rear grip while cornering. These arms give a wide adjustment range for precise rear camber, and replace the soft factory rubber bushings with smooth articulating Teflon lined rod ends. The kit replaces the factory links commonly referred to as the rear wishbone and rear guide links.

The kit combines gun drilled 2024 aluminum traction links with a 6061-T6 billet aluminum curved rear upper camber arm, both black anodized to resist corrosion and provide a durable finish. SPL's exclusive 360 degree 6061-T6 aluminum Rotating Clamp design allows quick, precise adjustment on the dogbone, while the curved upper arm uses SPL's double adjuster design so camber can be set without removing the arm from the vehicle. Clamps are tightened with blue anodized titanium socket head cap screws, saving further unsprung weight without compromising strength.

FK spherical bearings and rod ends are manufactured in Connecticut and use a Teflon liner for quiet operation, low friction and smooth articulation with no bushing deflection under load. The liner is self-lubricating and self-cleaning, and the PTFE is chemically bonded to the inner diameter of the race for very high load carrying capacity and greatly improved dynamic wear characteristics.

SPECS

• Wide rear camber adjustment range, adjustable on the car via the double adjuster
• Black anodized, gun drilled 2024 aluminum links
• 6061-T6 billet aluminum curved upper arm with included double adjuster
• 6061-T6 aluminum rotating clamps for a wider range of adjustment
• Titanium socket head cap screws
• Tapered stainless steel knuckle mount spacers
• Low friction three-piece Teflon lined FK rod ends
• PTFE liner operating temperature range: −65°F to 325°F
• Replaces the factory rear wishbone and rear guide links
• Sold as a complete kit for one car (four arms total)
• Made in the USA

PARTS INCLUDED

• Four SPL Parts rear upper arms — two curved upper camber arms and two traction (dogbone) links
• Tapered stainless steel knuckle mount spacers
• Titanium socket head cap screws and rotating clamps
• Complete kit as supplied by SPL Parts; see the installation instructions for the full bill of materials

TECH RESOURCES

Additional Parts Required

• Four-wheel alignment after installation — mandatory. Rear camber and toe both change when these arms are fitted.
• Professional installation is recommended; these are safety-critical rear suspension arms.
• Corner weighting is recommended for track use.
• To use the full rear camber range on a lowered car, pair these with adjustable rear toe links: SPL BMW F8X G8X Rear Toe Links.

Installation

• SPL Parts SPL RUA G8X rear upper arms — installation instructions (PDF)

Notes

• Year ranges are as published by SPL Parts for each chassis code. Confirm fitment with Speed Logic before ordering if you are unsure.

PART NUMBER

• SPL RUA G8X

VEHICLE APPLICATIONS