RPM Front Right Upper and Lower A-arms ARRMA Kraton Outcast 8S RPM81562

Overview

The RPM Front Right Upper and Lower A-arms for the ARRMA Kraton 8S and Outcast 8S represent a significant upgrade over stock suspension components for serious RC enthusiasts in the UK. These high-performance replacement A-arms are engineered specifically for the extreme demands of 26 lb (12 kg) monster trucks that are designed for high-flying, dirt-shredding, jump-killing action. If your stock A-arms aren't surviving the abuse these massive monsters can dish out, RPM's advanced replacement front A-arms offer the durability and performance you need for consistent, reliable off-road RC car action.

Designed with the backyard basher in mind, these suspension upgrades from RPM can handle serious abuse and come back for more. Whether you're a seasoned RC competitor or an enthusiastic weekend basher discovering advanced tuning options for your brushless RC monster truck, these A-arms deliver the engineering innovation you need. Made in the USA from RPM's trademark blend of ultra-durable materials, these front right upper and lower A-arms represent a thoughtful evolution in suspension design that addresses real-world failures experienced by RC drivers pushing their vehicles to the limit.

The RPM81562 part number represents the front right A-arm set, and when combined with the left set (RPM81522), you'll have a complete front suspension upgrade that transforms how your ARRMA Kraton or Outcast 8S handles impacts, landing forces, and extreme terrain challenges. This is a genuine performance upgrade for serious RC truck enthusiasts looking to extend their vehicle's lifespan whilst improving handling characteristics and crash resistance.

Key Features

• Triple Beam Lower A-arm Construction — The front lower A-arms feature an innovative triple beam design specifically engineered to spread impact energy across all three beams rather than concentrating it at single failure points, which is why this design is so effective for high-impact RC truck applications.
• Massive Beam Cross-Section — Each lower A-arm beam measures a substantial 5/8 inch (15.8 mm) tall by 3/8 inch (9.5 mm) wide, providing exceptional structural rigidity that reduces unwanted flex during normal suspension movement whilst still allowing controlled impact-absorption during hard landings and crashes.
• Dual Beam Upper A-arm Design — The front upper A-arms use a sophisticated dual beam construction where each beam measures 1/2 inch (12.7 mm) tall by 3/8 inch (9.5 mm) wide, delivering premium strength and responsiveness without the compromises of hollow tube designs.
• Eliminated Tube Over Hinge Pin — By removing the tube shape that sits over the hinge pin, RPM eliminated built-in molding stresses whilst simultaneously beefing up the leading edge hinge pin support, adding crucial strength and durability exactly where impacts concentrate force on RC suspension systems.
• Droop Stop Elimination — The inner cross brace has been repositioned away from the chassis entirely, eliminating the droop stop screws that were causing bent chassis plates under extreme impacts, a problem that plagued stock A-arms on high-performance 8S LiPo-powered monster trucks.
• Weight Reduction — These RPM A-arms are lighter than stock by 4.5 grams per upper and lower A-arm pair, reducing unsprung weight to improve suspension responsiveness and overall handling characteristics of your brushless RC monster truck.
• Fingernail Slot Access — Both upper and lower A-arms are intelligently molded with fingernail slots that provide easy access for removing the aluminium support ring at the pivot ball, making maintenance and repairs straightforward without requiring special tools.
• USA Manufacturing — Every RPM A-arm is made in the USA from their proven blend of ultra-durable materials, ensuring consistent quality and reliability that stands up to the demands of serious RC enthusiasts.

Technical Performance

The RPM Front Right Upper and Lower A-arms represent a fundamental advancement in suspension engineering for the ARRMA Kraton 8S and Outcast 8S platforms. The triple beam lower A-arm construction with those massive 5/8 inch by 3/8 inch beam cross-sections creates an exceptional balance between rigidity and impact absorption that stock plastic A-arms simply cannot achieve. Each beam is engineered to deflect slightly under extreme loads, distributing impact forces across the entire assembly rather than creating stress concentration points that lead to sudden failure. This is particularly important for 8S brushless RC trucks where the combination of high power output and extreme jump heights creates forces that stock components cannot withstand. The dual beam upper A-arms, with their 1/2 inch by 3/8 inch cross-sections, provide the precision control geometry your truck needs whilst the elimination of the hollow tube design reduces internal stress fractures that develop from repeated impacts. The repositioning of the inner cross brace away from the chassis represents perhaps the most important design change, as it eliminates the common failure mode where droop stop screws would bend the chassis plate itself under extreme impacts. This engineering decision reflects real-world testing data showing that protecting the main chassis structure is more important than having a mechanical droop stop, as a bent chassis plate creates cascading failures throughout the entire RC vehicle. The 4.5 gram weight reduction per A-arm pair contributes to improved suspension responsiveness and more predictable handling characteristics across various terrain types. These A-arms are compatible with ARRMA #330569 Spring Perches on the 8S versions of both the Kraton and Outcast platforms, ensuring perfect fitment and geometry without modification.

What's in the Box

• One front right upper A-arm
• One front right lower A-arm

What You Need to Complete

• Front left upper and lower A-arms (RPM81522) to complete a full front suspension upgrade
• Rear A-arms (RPM80812) if you wish to upgrade the entire suspension system for maximum consistency and durability
• Aluminium support rings (not included) if you wish to add pivot ball support rings, though the arms function properly without them
• Thread tap (not included) in case you need to thread the pivot ball holes beyond what the ball itself provides, though RPM recommends only 3-4 threads maximum to preserve thread-locking capability

Installation and Compatibility Notes

Compatibility: RPM A-arms for the ARRMA Kraton 8S and Outcast 8S work perfectly with vehicles using ARRMA #330569 Spring Perches. However, EXB models equipped with ARRMA #330740 Spring Perches may experience interference issues at both the shock mount and sway bar locations. RPM does not recommend installation on EXB vehicles unless you are prepared to modify the A-arms to eliminate binding at these points.

Installation Requirements: Like stock ARRMA A-arms, the RPM Kraton 8S versions are sold without threads in the pivot ball holes. If you encounter difficulty threading the pivot ball into the hole, RPM recommends carefully thread tapping the hole to create 3-4 threads. However, do not tap any further than this, as additional cut threads will negate the thread-locking capability of RPM's proprietary durable material blend.

What's Needed to Complete Your Front Suspension: One vehicle requires one left A-arm set (RPM81522) and one right A-arm set (RPM81562) for completion of the front end. These replace the front right upper A-arm from stock ARRMA part number ARA330561 and the front right lower A-arm from stock ARRMA part number ARA330589.

Frequently Asked Questions

• Will these RPM A-arms fit my ARRMA Kraton 8S or Outcast 8S? — Yes, these RPM A-arms are specifically engineered for both the ARRMA Kraton 8S and ARRMA Outcast 8S platforms. They directly replace the stock ARRMA A-arms (part numbers ARA330561 for upper and ARA330589 for lower). However, if you have an EXB model with ARRMA #330740 Spring Perches, you may experience interference issues and would need to modify the A-arms or springs to avoid binding at the shock mount and sway bar, which is why RPM does not recommend them for EXB applications.
• How much weight do these A-arms save compared to stock? — The RPM A-arms are 4.5 grams lighter than the stock ARRMA A-arms for each upper and lower pair, contributing to improved suspension responsiveness and more predictable handling characteristics for your brushless RC monster truck.
• Are these A-arms sold as a complete pair? — Each RPM81562 package contains one upper and one lower A-arm for the front right side of your vehicle. To complete a full front end upgrade, you will need to purchase the left side set (RPM81522) as well. To upgrade your entire suspension system, you can also purchase rear A-arms (RPM80812).
• Do these A-arms require any tools to install? — Standard RC tools will work for installation. If the pivot ball hole is difficult to thread, RPM recommends thread tapping the hole, though a tap is not included. RPM advises tapping only 3-4 threads to preserve the thread-locking capability of their durable material blend.
• What makes the triple beam lower A-arm design better than stock? — The triple beam construction spreads impact energy across three separate beams instead of concentrating it at single failure points like stock plastic A-arms do. Each beam measures 5/8 inch by 3/8 inch, creating an exceptional balance between rigidity that reduces flex during normal suspension movement and controlled deflection that absorbs impact energy during hard landings and crashes. This design prevents the bent chassis failures that plagued stock A-arms on high-impact applications.
• Why did RPM eliminate the droop stops? — Real-world testing showed that during extreme impacts, the droop stop screws would actually bend the main chassis plate, creating far worse structural damage than allowing some additional suspension droop. By eliminating the cross brace droop stops and repositioning the inner cross brace away from the chassis entirely, RPM prioritises protecting the main chassis structure, which is absolutely critical for vehicle reliability.
• Are these A-arms suitable for serious RC competition or just casual bashing? — These A-arms are designed for serious abuse and are suitable for both competitive RC driving and extreme bashing applications. The engineering innovations address real failure modes that occur under high-impact conditions, making them ideal for any enthusiast pushing their ARRMA Kraton 8S or Outcast 8S to the limit, whether in organised competition or weekend bashings.

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 Front Right Upper and Lower A-arms Arrma Kraton/Outcast 8s RPM81562 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.