What camber and toe changes does the factory rear knuckle bushing cause on the E36 and E46?

The factory rubber knuckle bushing deflects under the lateral loads of cornering, the longitudinal loads of hard braking, and the combined loads of trail-braking into a corner. As the rubber compresses under these forces, the knuckle shifts slightly within the bushing, which changes both camber and toe away from their aligned positions at exactly the moments when consistent geometry matters most. Replacing the rubber with a spherical bearing removes that compliance; the knuckle stays in its aligned position under all load conditions.

What is the difference between the SPL RKB E36, the RTAB E36, and the RUAB E36?

These are three separate bushing kits targeting different rear suspension positions on the E36, E46, and Z4. The RKB E36 covers the rear knuckle bushing positions. The RTAB E36 covers the rear trailing arm bushing positions ($359.00). The RUAB E36 covers the rear upper arm bushing positions ($199.00). All three use the same FK spherical bearing and CNC aluminum shell construction. Installing all three completes a full spherical bearing rear suspension refresh on one car, eliminating rubber deflection at every rear bushing position simultaneously.

Are the aluminum bearing shells machined to any specific tolerance?

Yes. The 6061-T6 aluminum bearing shells are CNC-machined to 1/1000th-inch tolerance. This precision is required to maintain exact bearing position within the rear knuckle and to ensure a consistent press fit that holds dimensional accuracy over time through thermal cycling and suspension load cycles.

What temperature range do the FK Teflon-lined bearings operate within?

The Teflon liner in the FK Racing bearings operates reliably from -65°F to 325°F, covering the full temperature range of track use, cold-weather street driving, and sustained high-load cornering. The Teflon liner is chemically bonded to the inner diameter of the race and requires no external grease for lubrication.

Does installing this kit require a full rear alignment afterward?

Yes. Replacing the rear knuckle bushings with spherical bearings changes the compliance characteristics at the knuckle. While the alignment settings do not change during installation itself, a full rear alignment check is strongly recommended after installation to confirm that camber and toe are at the desired target settings and to take advantage of the improved geometry consistency the spherical bearings provide.

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Description

SPL Parts Rear Knuckle Bushings for E36 / E46 / E8x BMW 3 Series / Z4

The SPL Parts RKB E36 eliminates that deflection at the knuckle. FK Racing spherical bearings with self-lubricating Teflon liners replace the factory rubber, articulating freely under load without deflecting; which means geometry stays where it was set rather than shifting with load cycles. The camber and toe change that the rubber bushing introduces under high lateral or longitudinal force is removed, and the rear suspension responds to load changes predictably and consistently. For any E36, E46, or E85 / E86 Z4 that sees performance driving; whether on road or track; this is a change that registers in handling feel almost immediately. The aluminum bearing shells are CNC-machined to 1/1000th of an inch tolerance, which is the accuracy required for a bushing that needs to maintain precise bearing position against a knuckle while the suspension articulates through its full range. The press fit of the aluminum shell to the knuckle is exact and repeatable, which matters both for initial installation accuracy and for long-term dimensional stability. The Teflon liner requires no grease, operates reliably from -65°F to 325°F, and provides a long service life under track and street use conditions.

Features

Replaces factory rear knuckle rubber bushings with FK Racing spherical bearings using self-lubricating Teflon liners; eliminates bushing deflection under load
Eliminates camber and toe change under lateral, longitudinal, and braking loads; geometry holds its aligned position throughout the suspension’s range of motion
CNC-machined 6061-T6 aluminum bearing shells machined to 1/1000th-inch tolerance; precise fit to the rear knuckle for accurate bearing positioning and long-term dimensional stability
Teflon-lined FK bearings require no grease; operating temperature range of -65°F to 325°F; suitable for sustained street and track use
Low friction, smooth articulation throughout the full range of rear suspension travel; no binding at any suspension position
Complete one-car kit covering all rear knuckle bushing positions on one vehicle
Made in the USA

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 318d: E46 | 1999-2005
BMW 320d: E46 | 1999-2005
BMW 330d: E46 | 2001-2005
BMW 316i: E36, E46 | 1992-2005
BMW 318i: E36, E46 | 1992-2005
BMW 320i: E36, E46 | 1992-2005
BMW 323i: E36, E46 | 1992-2001
BMW 325i: E36, E46 | 1992-2005
BMW 328i: E36, E46 | 1992-2000
BMW 330i: E46 | 2001-2005
BMW 318is: E36 | 1992-1999
BMW 318ti: E36 | 1995-1999
BMW 325xi: E46 | 2001-2005
BMW 330xi: E46 | 2001-2005
BMW M3: E36, E46 | 1992-2006
BMW Z4 sDrive20i: E85 | 2003-2008
BMW Z4 sDrive25i: E85 | 2003-2008
BMW Z4 sDrive30i: E85 | 2003-2008
BMW Z4 M: E85, E86 | 2006-2008
BMW Z4 Coupé 3.0si: E86 | 2006-2008

Notes

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

Frequently Asked Questions

What camber and toe changes does the factory rear knuckle bushing cause on the E36 and E46? The factory rubber knuckle bushing deflects under the lateral loads of cornering, the longitudinal loads of hard braking, and the combined loads of trail-braking into a corner. As the rubber compresses under these forces, the knuckle shifts slightly within the bushing, which changes both camber and toe away from their aligned positions at exactly the moments when consistent geometry matters most. Replacing the rubber with a spherical bearing removes that compliance; the knuckle stays in its aligned position under all load conditions.
What is the difference between the SPL RKB E36, the RTAB E36, and the RUAB E36? These are three separate bushing kits targeting different rear suspension positions on the E36, E46, and Z4. The RKB E36 covers the rear knuckle bushing positions. The RTAB E36 covers the rear trailing arm bushing positions. The RUAB E36 covers the rear upper arm bushing positions. All three use the same FK spherical bearing and CNC aluminum shell construction. Installing all three completes a full spherical bearing rear suspension refresh on one car, eliminating rubber deflection at every rear bushing position simultaneously.
Are the aluminum bearing shells machined to any specific tolerance? Yes. The 6061-T6 aluminum bearing shells are CNC-machined to 1/1000th-inch tolerance. This precision is required to maintain exact bearing position within the rear knuckle and to ensure a consistent press fit that holds dimensional accuracy over time through thermal cycling and suspension load cycles.
What temperature range do the FK Teflon-lined bearings operate within? The Teflon liner in the FK Racing bearings operates reliably from -65°F to 325°F, covering the full temperature range of track use, cold-weather street driving, and sustained high-load cornering. The Teflon liner is chemically bonded to the inner diameter of the race and requires no external grease for lubrication.
Does installing this kit require a full rear alignment afterward? Yes. Replacing the rear knuckle bushings with spherical bearings changes the compliance characteristics at the knuckle. While the alignment settings do not change during installation itself, a full rear alignment check is strongly recommended after installation to confirm that camber and toe are at the desired target settings and to take advantage of the improved geometry consistency the spherical bearings provide.

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 Knuckle Bushings for E36 / E46 / E8x BMW 3 Series / Z4 [SPLRKBE36]

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SPL Parts Rear Knuckle Bushings for E36 / E46 / E8x BMW 3 Series / Z4

Features

Specifications

Applications

Notes

Frequently Asked Questions

About SPL Parts

Reviews