What is the difference between the SPL CRB G8X and the SPL CRB E9X?

These are two separate parts for two different BMW platform generations. The CRB E9X fits E9X, E8X, and F8X models. The CRB G8X is engineered specifically for the G8X front caster rod arm geometry. The G8X platform uses a different caster rod arm configuration from the previous generation, and the two parts are not interchangeable. Confirm your platform before ordering.

Does the SPL CRB G8X fit the G87 M2?

The source listing specifies the G8X M3 and M4 (G80, G82, G83). The G87 M2 uses a different front caster rod configuration. Confirm G87 M2 compatibility directly with SPL Parts before ordering if you have a G87 M2.

What does +/- 2 degrees of caster adjustment provide in practice?

Two degrees of adjustment in each direction is a meaningful range for the G8X platform. It covers the caster deficit most builds accumulate after lowering, allows the left and right caster values to be equalized, and provides range to optimize front caster for the specific alignment target; whether that's more caster for sharper turn-in and better high-speed stability on a track build or simply bringing a lowered car back to a balanced setting. The +/- 2 degree range goes beyond what the factory eccentric alone can provide.

Are the OEM caster rod arms included?

No. The CRB G8X 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.

How does this bushing differ from the factory rubber in actual driving feel?

The factory rubber bushing compresses under sustained braking and cornering load, which allows the caster rod to deflect away from its set position at the moments when consistent geometry matters most. Under hard braking, that deflection changes the front caster value and contributes to instability. The FK spherical bearing articulates without deflecting; caster holds at its set value throughout the full range of braking, cornering, and acceleration loads. Drivers consistently notice the improvement as more stable and consistent braking, crisper turn-in, and more direct steering feedback from the front end.

Description

Additional Info

Shipping policy

BP PRICING DIFFERENCE

Reviews

Product Inquiry

Description

SPL Parts Adjustable Front Caster Rod Monoball Bushings for G8x BMW M3 / M4

The G8x M3 and M4’s front caster rod connects the front lower control arm to the subframe and defines the front caster angle; one of the most influential geometry settings for steering feel, turn-in response, high-speed stability, and the car’s tendency to self-center under power. The factory rubber bushing in this arm deflects under the sustained braking and cornering loads the G8X generates, allowing caster to shift away from its set value dynamically during a corner or under hard braking. The factory adjustment range is also limited; adequate for bringing a car to within factory specification, not adequate for the caster targets performance builds require or for equalizing left-to-right caster after lowering. The SPL Parts CRB G8X replaces the factory rubber with a 1-inch FK Racing spherical bearing using a self-lubricating Teflon liner. The bearing articulates freely without deflecting, holding the caster rod position under all load conditions rather than shifting with the rubber’s compliance. Braking becomes more stable, turn-in sharper, and the front end communicates what it’s doing with more precision and consistency.

Features

Replaces factory rubber front caster rod bushings with 1-inch FK Racing spherical bearings; eliminates bushing deflection under braking and cornering loads; front caster holds position under all load conditions
Self-lubricating Teflon-lined FK bearings; no maintenance required; self-cleaning design
CNC-machined 6061-T6 aluminum offset bearing spacers provide +/- 2 degrees of caster adjustment beyond the factory eccentric bolt range
6061-T6 aluminum bearing housing with outer knurl; presses into the OEM caster rod arm without modification
Improves braking stability, turn-in response, and steering feedback by maintaining consistent caster under load

Specifications

Material: Billet aluminum mounts
Bushings: 1″ FK USA spherical bearings, Teflon-lined
Adjustment: Caster — wide range
Sold As: Pair (one car)
Origin: Made in the USA

Applications

BMW M3: G80, G81 | 2021-present
BMW M4: G82, G83 | 2021-present

Notes

Installation Instructions
Not compatible with G87 M2
OEM caster rod arms are not included
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 CRB G8X and the SPL CRB E9X? These are two separate parts for two different BMW platform generations. The CRB E9z fits E9x, E8x, and F8x models. The CRB G8X is engineered specifically for the G8x front caster rod arm geometry. The G8x platform uses a different caster rod arm configuration from the previous generation, and the two parts are not interchangeable. Confirm your platform before ordering.
Does the SPL CRB G8X fit the G87 M2? The source listing specifies the G8x M3 and M4. The G87 M2 uses a different front caster rod configuration. Confirm G87 M2 compatibility directly with SPL Parts before ordering if you have a G87 M2.
What does +/- 2 degrees of caster adjustment provide in practice? Two degrees of adjustment in each direction is a meaningful range for the G8x platform. It covers the caster deficit most builds accumulate after lowering, allows the left and right caster values to be equalized, and provides range to optimize front caster for the specific alignment target; whether that’s more caster for sharper turn-in and better high-speed stability on a track build or simply bringing a lowered car back to a balanced setting. The +/- 2 degree range goes beyond what the factory eccentric alone can provide.
Are the OEM caster rod arms included? No. The CRB G8X 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.
How does this bushing differ from the factory rubber in actual driving feel? The factory rubber bushing compresses under sustained braking and cornering load, which allows the caster rod to deflect away from its set position at the moments when consistent geometry matters most. Under hard braking, that deflection changes the front caster value and contributes to instability. The FK spherical bearing articulates without deflecting; caster holds at its set value throughout the full range of braking, cornering, and acceleration loads. Drivers consistently notice the improvement as more stable and consistent braking, crisper turn-in, and more direct steering feedback from the front end.

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.

Reviews

There are no reviews yet.

Only logged in customers who have purchased this product may leave a review.

Product Inquiry

First Name (*required)

Last Name (*required)

Your E-Mail (*required)

Telephone Number (*required)

Country (*required)

Vehicle Year / Make / Model (*required)

Please Explain What do you want to do with your vehicle

Additional Information (optional)

I agree to the terms & conditions and privacy policy and to have Bulletproof Automotive LLC contact me for promotion, marketing and other purposes via email, phone or SMS message.

SPL Parts Adjustable Front Caster Rod Monoball Bushings for G8x BMW M3 / M4 [SPLCRBG8X]

Guaranteed Safe Checkout

SPL Parts Adjustable Front Caster Rod Monoball Bushings for G8x BMW M3 / M4

Features

Specifications

Applications

Notes

Frequently Asked Questions

About SPL Parts

Reviews