RPM Rear A-Arms Arrma Kraton 8S Outcast 8S Triple Beam Suspension RPM80812

Overview

The RPM Rear A-Arms for the Arrma Kraton and Outcast 8S (part number RPM80812) represent a premium suspension upgrade designed specifically for serious RC enthusiasts who demand durability and performance from their off-road machines. The ARRMA Kraton 8S is 26 lbs (12 kg) of high-flying, dirt-shredding, jump-killing fun, and if your standard A-arms aren't up to the abuse this massive monster truck can dish out, these RPM upgrades are the solution you've been looking for. Whether you're a weekend basher exploring the world of RC cars UK or a committed enthusiast pushing your vehicle to its limits, these replacement rear A-arms are engineered to handle serious abuse and come back for more.

RPM has built a reputation for manufacturing aftermarket RC suspension components that outperform stock parts, and these rear A-arms exemplify that commitment to quality. Designed with the backyard basher in mind, they're manufactured in the USA from RPM's trademark blend of ultra-durable nylon materials that provide a lifetime of protection you can trust. These aren't just a simple swap-in part; they represent a fundamental upgrade to your truck's suspension geometry and impact resistance, making them an essential consideration for anyone running a brushless RC monster truck like the Kraton 8S.

Available as a direct replacement for the stock ARRMA part number ARA330590, these rear A-arms integrate seamlessly into your existing setup whilst providing measurably improved performance characteristics. For UK RC hobbyists seeking genuine, authorised upgrades from trusted manufacturers, RPM remains one of the most recognised names in the industry, consistently delivering products that exceed expectations and provide genuine value for money.

Key Features

• Triple Beam Construction — The rear A-arms utilise a sophisticated triple-beam design that spreads impact energy across all three beams rather than concentrating it in a single point, dramatically reducing the likelihood of catastrophic failure during high-impact landings and crashes that are inevitable when pushing a high-performance RC monster truck to its limits.
• Massive Cross-Section Dimensions — Each of the three beams features an impressive cross-section measuring 5/8 inch (15.8 mm) tall by 3/8 inch (9.5 mm) wide, providing exceptional rigidity and strength whilst remaining relatively lightweight for a suspension component of this calibre.
• Optimised Flex Characteristics — The engineering carefully balances structural stiffness during normal suspension movement to reduce unwanted flex, whilst still allowing sufficient impact-absorption during those inevitable not-so-perfect landings and crashes that test the limits of your RC vehicle.
• Eliminated Droop Stop Design — RPM moved the inner cross-brace away from the chassis and eliminated the droop stop entirely, a counter-intuitive design choice based on extensive testing that revealed chassis plates were bending at the droop stops under extreme impacts, ultimately causing more damage than the improved geometry prevents.
• Chassis Protection Philosophy — By preventing the suspension from bottoming out against the chassis plate, these A-arms protect one of the most expensive and difficult-to-replace components on your truck, extending the overall lifespan of your investment and reducing repair costs.
• Ultra-Durable Materials — Manufactured from RPM's proprietary engineering blend of incredibly strong nylons, these arms provide unmatched durability compared to stock plastic components whilst maintaining a weight advantage over heavier aluminium alternatives.
• Direct OEM Replacement — These rear A-arms are engineered as a direct replacement for the stock ARRMA ARA330590 parts, ensuring perfect fitment and compatibility with your Kraton or Outcast 8S without requiring modification or additional components.
• Sold as a Pair — Each purchase includes both rear A-arms, everything you need to complete the upgrade on your RC truck without purchasing additional components or making a second order.
• Made in the USA — RPM manufactures these components in the USA using strict quality control standards, ensuring consistent performance and reliability across every unit shipped to RC enthusiasts worldwide, including those in the UK RC market.
• Compatible with RPM Mud Guards — These A-arms are specifically designed to work with RPM Mud Guards (sold separately), which further extend shock life and reduce maintenance by preventing dirt and debris from sandblasting your shocks and shock shafts during aggressive off-road use.

Technical Performance

The RPM Rear A-Arms for the Arrma Kraton/Outcast 8S represent a significant engineering achievement in suspension design for high-performance RC monster trucks. The triple-beam construction philosophy demonstrates genuine engineering innovation; rather than creating a single thick beam, RPM's engineers distributed material across three separate beams, each measuring 5/8 inch (15.8 mm) in height and 3/8 inch (9.5 mm) in width. This approach provides multiple advantages: the distributed geometry spreads impact forces across the entire structure rather than concentrating stress at single points, significantly increasing the overall strength-to-weight ratio. The material science behind RPM's proprietary nylon blend is particularly impressive—these ultra-durable plastics offer exceptional impact resistance comparable to much heavier aluminium alternatives, whilst maintaining a lightweight profile that doesn't negatively impact your truck's performance characteristics or battery runtime. The decision to eliminate the traditional droop stop was based on real-world testing where RPM engineers observed that extreme impacts were actually bending the chassis plate at the droop stop location, causing more damage than allowing slightly increased suspension travel. This insight demonstrates that RPM doesn't simply copy competitor designs but actively tests and refines their engineering based on field performance data. The repositioned inner cross-brace provides the necessary lateral support without the harsh contact point that was causing chassis damage. For users of brushless RC monster trucks like the ARRMA Kraton 8S—which delivers genuinely high power output from modern brushless motors—this upgraded suspension geometry translates into noticeably improved landing characteristics, reduced maintenance intervals for your shock absorbers, and increased overall truck durability across repeated hard-impact scenarios that are typical during aggressive basher sessions.

What's in the Box

• RPM Rear A-Arms for Arrma Kraton 8S and Outcast 8S (pair)
• Assembly hardware (mounting bolts and fasteners for installation)

Frequently Asked Questions

• Will these RPM rear A-arms fit my stock ARRMA Kraton 8S without modifications? — Yes, these RPM rear A-arms are engineered as a direct replacement for the stock ARRMA part number ARA330590, meaning they bolt directly into your existing suspension mounts without requiring any modification to your truck's chassis or geometry. This plug-and-play compatibility is one of the major advantages of choosing RPM upgrades for your RC car UK.
• How much stronger are these A-arms compared to the stock ARRMA parts? — The triple-beam construction with massive 5/8 inch by 3/8 inch beam cross-sections provides significantly greater rigidity and impact resistance compared to stock plastic A-arms. The distributed load-bearing design means they can absorb impacts that would break stock components, making them essential for anyone regularly jumping or high-impact bashing their Kraton 8S.
• Are these rear A-arms suitable for beginners? — Whilst these are suspension components rather than a complete truck, they're ideal for anyone who has experienced broken A-arms or is upgrading to a more durable setup. The installation is straightforward for anyone with basic RC maintenance knowledge and a few hand tools. If you're new to upgrading your RC monster truck, these represent one of the best value upgrades you can make.
• What is the weight of these RPM rear A-arms? — Whilst the source documentation focuses more on the overall design philosophy than individual component weights, RPM's engineering approach prioritises lightweight construction through efficient geometry rather than material thickness, ensuring these upgrades don't significantly impact your truck's overall weight or performance characteristics.
• Can I use RPM Mud Guards with these A-arms? — Yes, in fact, these rear A-arms are specifically designed to be compatible with RPM Mud Guards (product number 80642). The mud guards work exclusively with the RPM 80812 A-arms and cannot be fitted to stock or other aftermarket A-arms, making them an ideal complementary upgrade that protects your shocks and shock shafts from sandblasting and debris.
• What maintenance advantages do these A-arms provide? — Beyond their superior durability, these rear A-arms work with RPM Mud Guards to reduce maintenance of your shock shaft seals and prevent debris from reaching your rear driveline and suspension components, meaning your truck will run smoother between cleanings and require less frequent maintenance overall.
• Are these arms made in the USA? — Yes, RPM manufactures these rear A-arms in the USA using their proprietary engineering blend of ultra-durable nylon materials, ensuring consistent quality and supporting domestic manufacturing standards that many serious RC enthusiasts prefer.
• Will these improve my truck's suspension performance? — Absolutely. By reducing unwanted flex during normal suspension movement whilst still allowing proper impact absorption, these A-arms provide a noticeable improvement in your truck's handling characteristics, landing geometry, and overall suspension responsiveness during aggressive bashing sessions.

Why Buy from RC Model Shop?

RC Model Shop is a trusted UK RC retailer and authorised dealer for all the brands we stock, including Traxxas, ARRMA, Losi, FTX, Hobbywing, Spektrum and more. Based in Walsall, we have a physical store where customers are welcome to come in, view products and purchase in store. Whether you are a seasoned competitor, a weekend basher, or just discovering the world of RC for the first time, our team of experienced RC enthusiasts is here to help you find the perfect setup and provide ongoing support. Order the RPM Rear A-Arms for the Arrma Kraton/ Outcast 8s RPM80812 Upgrade part for ARA330590 today with confidence, knowing you are buying from an authorised retailer with genuine products, expert knowledge and a commitment to customer satisfaction. Shop online or visit us in Walsall — we look forward to helping you get the most out of your RC experience.