SPL Front Caster Rod Bushings – BMW E8X / E9X / F2X / F3X / F8X / G2X / G8X / G29 / G42 & GR Supra

OVERVIEW

SPL Parts FKS Series Front Caster Rod Bushings (CRB) replace the stock flexible rubber caster rod bushing — the largest and softest bush in the front of a modern BMW — with a low friction, articulating spherical bearing, without replacing the whole arm. The OEM bushing deflects under braking, steering and acceleration, so the wheel moves backwards in the arch, caster changes, the steering goes vague and bumpsteer shifts; the spherical bearing eliminates that deflection and the binding that limits droop travel, maintaining optimum geometry under load for sharper braking and handling feedback.

Two versions are offered. The adjustable bushing (CRB) adds CNC machined 6061-T6 offset spacers that provide caster adjustment (±4° on E9X / F3X / G29, ±2° on G8X), letting you dial in steering feel, correct side-to-side caster split and move the wheel to clear a tire. The non-adjustable bushing (CRBN) keeps factory caster and simply removes the deflection — the direct-swap choice for a street car. Both use massive 1" FK Racing bearings with self-lubricating PTFE liners in a 6061-T6 aluminum housing with an outer knurl. The G2X / G42 version replaces the large hydraulic OEM bushing and also reduces front wheel hop on xDrive cars under hard launches.

SPECS

• Press-in replacement for the factory front caster rod (tension rod) bushing — keeps the original control arm
• 6061-T6 aluminum bearing housing with outer knurl
• Massive 1" FK Racing PTFE-lined spherical bearings (G2X: FK USA PTFE-lined spherical bearing with zinc plated snap rings)
• Adjustable versions: 6061-T6 aluminum offset spacers for caster adjustment (±4° E9X / F3X / G29, ±2° G8X)
• Non-adjustable versions retain factory caster geometry
• Eliminates fore-aft front wheel deflection under braking
• OEM arms not included
• Sold as a pair (one pair per vehicle)
• Made in the USA

PARTS INCLUDED

• Two SPL Parts front caster rod bushings with FK spherical bearings (adjustable versions include offset spacers)
• 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. Caster and front toe must be reset.
• A hydraulic press is required to remove the factory bushing and fit these. This is not a driveway job — budget shop time.
• Professional installation is recommended; these are safety-critical suspension components.
• For full caster and anti-dive adjustment on a complete arm, see the SPL Front Tension Rods / Caster Rods instead.
• SPL recommends a quality coilover with suitable spring rates on the G2X / G42 to keep NVH in check.

Installation

• SPL Parts SPL CRB E9X adjustable caster rod bushings — installation instructions (PDF)
• SPL Parts SPL CRBN E9X non-adjustable caster rod bushings — installation instructions (PDF)
• SPL Parts SPL CRB F3X adjustable caster rod bushings — installation instructions (PDF)
• SPL Parts SPL CRBN F3X non-adjustable caster rod bushings — installation instructions (PDF)
• SPL Parts SPL CRB F3iX adjustable caster rod bushings (xDrive) — installation instructions (PDF)
• SPL Parts SPL CRBN F3iX non-adjustable caster rod bushings (xDrive) — installation instructions (PDF)
• SPL Parts SPL CRB G8X adjustable caster rod bushings — installation instructions (PDF)
• SPL Parts SPL CRB G29 adjustable caster rod bushings — installation instructions (PDF)
• SPL Parts SPL CRBN G29 non-adjustable caster rod bushings — installation instructions (PDF)
• SPL has not published a dedicated installation document for SPL CRB G2X; Speed Logic will confirm the procedure before you install.

Notes

• Drive layout matters. SPL CRB E9X, SPL CRBN E9X, SPL CRB F3X and SPL CRBN F3X are for rear-wheel-drive cars only. xDrive F2X / F3X cars take SPL CRB F3iX or SPL CRBN F3iX. SPL CRB G2X fits both sDrive and xDrive.
• Replaces BMW 31 12 6 855 743 (F3X RWD), 31 12 6 854 729 (F3X xDrive) and 31 10 6 894 675 / 676 (G2X / G42).
• Expect more harshness over rough roads and hard bumps, slightly more road noise and a greater chance of tramlining; ride on smoother roads still improves over stock.
• Price is for parts only; labor, pressing and alignment are not included.
• Confirm your exact model, chassis code and drivetrain with Speed Logic before ordering.

PART NUMBER

• SPL CRB E9X — E8X / E9X / F8X adjustable (RWD only)
• SPL CRBN E9X — E8X / E9X / F8X non-adjustable (RWD only)
• SPL CRB F3X — F2X / F3X adjustable (RWD only)
• SPL CRBN F3X — F2X / F3X non-adjustable (RWD only)
• SPL CRB F3iX — F2X / F3X xDrive adjustable
• SPL CRBN F3iX — F2X / F3X xDrive non-adjustable
• SPL CRB G2X — G20 / G22 / G23 / G42 adjustable, sDrive and xDrive
• SPL CRB G8X — G80 M3, G82 / G83 M4 adjustable
• SPL CRB G29 — Toyota GR Supra A90, BMW Z4 G29 adjustable
• SPL CRBN G29 — Toyota GR Supra A90, BMW Z4 G29 non-adjustable

VEHICLE APPLICATIONS