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

These three kits target three separate rear suspension bushing positions on the E36, E46, and Z4. The RUAB E36 covers the rear upper arm bushing positions. The RTAB E36 covers the rear trailing arm bushing positions ($359.00). The RKB E36 covers the rear knuckle bushing positions ($399.00). All three use the same FK spherical bearing and CNC aluminum shell construction. Installing all three completes a full spherical bearing rear suspension, eliminating rubber deflection at every rear bushing position simultaneously.

Why is the rear upper arm bushing specifically important for camber and toe consistency?

The rear upper arm governs the position of the top of the rear knuckle, which directly determines rear camber. When the upper arm bushing deflects under lateral load, the top of the knuckle moves relative to its set position, changing the camber angle dynamically during a corner. Under hard braking, longitudinal deflection at the upper arm can also contribute to toe change. The SPL RUAB E36 eliminates deflection at both the subframe and knuckle connections of the upper arm, holding camber and toe at their aligned values under all load conditions.

Is this the least expensive of the three E36/E46/Z4 rear bushing kits?

Yes. At $199.00, the RUAB E36 is the lower-cost entry point in SPL's E36/E46/Z4 rear bushing three-kit program. The RTAB E36 is $359.00 and the RKB E36 is $399.00. All three kits use the same FK spherical bearing and CNC aluminum construction standard; the price difference reflects the number of bushing positions in each kit rather than a difference in bearing quality or specification.

Can I install just the upper arm bushings without the trailing arm or knuckle bushings?

Yes. The RUAB E36 can be installed independently. However, leaving the trailing arm and knuckle bushing positions in factory rubber means those positions continue to deflect under load, partially offsetting the gains from the upper arm upgrade. Shops that build E36 and E46 builds for track use consistently recommend addressing all three positions simultaneously for the full benefit.

Does installing this kit require a full rear alignment?

Yes. Replacing the upper arm bushings changes the compliance characteristics at the upper arm connection and should be followed by a full rear alignment to confirm camber and toe are at the desired target values with the new bushings installed.

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Description

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

The rear upper arm on the BMW E36, E46, and E85/E86 Z4 controls the inboard and outboard position of the top of the rear knuckle and directly influences rear camber. The rubber bushings at the upper arm connection deflect under the lateral and longitudinal loads of hard cornering, braking, and acceleration, allowing the upper arm to move relative to its set position and changing the camber angle dynamically. That camber change affects rear tire contact patch, rear grip consistency, and the stability the driver feels under load; it is one of the reasons the rear end of these cars can feel less planted on track than the suspension geometry would suggest it should be. The SPL RUAB E36 replaces those rubber bushings with FK Racing spherical bearings using self-lubricating Teflon liners, seated in CNC-machined 6061-T6 aluminum bearing shells. The bearing articulates freely through the full suspension range of motion without deflecting, holding the upper arm in its set position under load. Camber and toe stay where they were aligned rather than shifting under cornering and braking forces, giving the rear suspension the geometry consistency the driver expects and the tires need to perform at their best.

Features

Replaces factory rear upper arm rubber bushings with FK Racing spherical bearings using self-lubricating Teflon liners; eliminates bushing deflection and binding under lateral and longitudinal loads
Removes camber and toe change that occurs under load at the upper arm connection; rear geometry holds its aligned values through cornering, braking, and acceleration
CNC-machined 6061-T6 aluminum bearing shells machined to +/- .001-inch tolerance; precise, repeatable press-fit with long-term dimensional stability
Teflon liner self-lubricating; no maintenance or grease required; operates reliably through sustained street and track use
Low friction, smooth articulation through the full range of rear suspension travel; no binding at any suspension position

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 Roadster: E85 | 2006-2008
BMW Z4 Coupé 3.0si: E86 | 2006-2008
BMW Z4 M Coupé: E86 | 2006-2008

Notes

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 RUAB E36, the RTAB E36, and the RKB E36? These three kits target three separate rear suspension bushing positions on the E36, E46, and Z4. The RUAB E36 covers the rear upper arm bushing positions; the points where the upper control arm attaches to both the subframe and the rear knuckle. The RTAB E36 covers the rear trailing arm bushing positions. The RKB E36 covers the rear knuckle 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, eliminating rubber deflection at every rear bushing position simultaneously.
Why is the rear upper arm bushing specifically important for camber and toe consistency? The rear upper arm governs the position of the top of the rear knuckle, which directly determines rear camber. When the upper arm bushing deflects under lateral load, the top of the knuckle moves relative to its set position, changing the camber angle dynamically during a corner. Under hard braking, longitudinal deflection at the upper arm can also contribute to toe change. Both forms of deflection reduce rear geometry consistency and make the car’s balance less predictable at the limit. The SPL RUAB E36 eliminates deflection at both the subframe and knuckle connections of the upper arm, holding camber and toe at their aligned values under all load conditions.
Can I install just the upper arm bushings without the trailing arm or knuckle bushings? Yes. The RUAB E36 can be installed independently. However, leaving the trailing arm and knuckle bushing positions in factory rubber means those positions continue to deflect under load, partially offsetting the gains from the upper arm upgrade. Shops that build E36 and E46 builds for track use consistently recommend addressing all three positions simultaneously for the full benefit.
Does installing this kit require a full rear alignment? Yes. Replacing the upper arm bushings changes the compliance characteristics at the upper arm connection and should be followed by a full rear alignment to confirm camber and toe are at the desired target values with the new bushings installed.

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 Upper Arm Bushings for E36 / E46 / E8x BMW 3 Series / Z4 [SPLRUABE36]

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

Features

Specifications

Applications

Notes

Frequently Asked Questions

About SPL Parts

Reviews