Overview
The ARRMA 1/10 KRATON 4S 4X4 BLX Centre Diff Speed Monster Truck RTR in Green is a fully assembled, ready-to-run RC monster truck that delivers serious speed, stability, and durability for bashers of all skill levels. This is a genuine 4S LiPo-capable brushless RC car UK enthusiasts have been waiting for — combining the speed thrills of larger 6S machines with the affordability and accessibility of smaller bashers. Whether you're looking for a high-speed RC monster truck ready to run straight out of the box, or you want a serious platform for weekend bashing sessions, the KRATON 4S represents the perfect sweet spot in the ARRMA lineup.
The latest evolution of ARRMA's proven 4S BLX platform brings significant improvements across the board. The standout feature is the all-new oil-filled aluminium-cased centre differential, which provides ultimate traction and handling across any surface — from dirt tracks to grass and paved ground. Combined with a completely revised composite chassis that accepts the centre diff module with added hinge pin bracing and integrated dirt drain, this truck is engineered for punishment. ARRMA has also upgraded the entire Spektrum brushless electronics package to deliver improved performance and reliability, making this an excellent choice for anyone seeking a brushless RC monster truck with genuine speed (55+ mph capability) and engineering excellence.
What sets the KRATON 4S apart from similar ready-to-run RC vehicles is its combination of proven durability, modular design philosophy, and serious performance credentials. The truck comes fully factory-assembled and finished in a striking green colour scheme, complete with a three-channel Spektrum 2.4GHz radio system and dual protocol receiver. With massive dBoots COPPERHEAD 2 LP vented tyres, a wide 450mm front and rear track, and a long 547mm wheelbase for exceptional stability, this is a genuine all-terrain speed machine designed to handle the demands of serious bashers.
Key Features
- Oil-Filled Aluminium-Cased Centre Differential — The new centre diff module is the hero feature of this generation, providing incredible traction and handling grip regardless of surface conditions. This means improved cornering control, reduced wheel spin, and more predictable handling at speed, making the KRATON 4S noticeably more controllable than earlier centre diff-less versions.
- Updated Spektrum FIRMA 120A V2 Smart Brushless ESC — This waterproof and dustproof electronic speed controller is rated for 120 amps and supports 2S, 3S, and 4S LiPo batteries, delivering the power needed for true 55+ mph performance. The integrated cooling fan keeps temperatures down during extreme running, whilst Spektrum SMART Technology integration allows for user programmable punch, brake, BEC, reverse speed, and motor timing adjustments to perfectly tune the truck to your driving style.
- Higher Torque Spektrum S662 Metal-Geared Digital Servo — This servo features 17kg/236oz-in of torque output, steel internal gears with a 25T output spline, and an alloy case centre for improved heat dissipation. The 0.15 second response time at 60 degrees (at 7.4V operation) means sharp, responsive steering even at high speeds, essential for maintaining control when pushing 55+ mph.
- Spektrum FIRMA 3668 2400Kv Brushless Motor — This 4-pole construction motor is 4S LiPo ready and features a beautifully etched aluminium can, strong 5mm shaft, and gold 4mm bullet connectors for reliable connection. The integrated heatsink and fan keep motor temperatures down during sustained high-speed running, preserving performance and extending motor lifespan.
- Revised Composite Chassis with Dirt Protection — The updated chassis design specifically accommodates the centre differential module whilst incorporating additional safety features. It includes hinge pin bracing for added strength, an integrated dirt drain to keep debris out of critical components, wishbone dirt guards protecting rear driveshafts, outdrive protectors, and taller side guards for maximum impact protection.
- EXB All-Metal Gear Differentials — Front and rear differentials are built with proven steel main and input gears, providing reliability and durability even under extreme bashing conditions. This ensures consistent torque delivery and reduces risk of gear failure during hard acceleration or impact.
- EXB CVD Front and Rear Driveshafts — The extreme bash composite slider driveshafts with steel couplings provide unstoppable power delivery whilst absorbing impact from jumps and rough terrain. These represent significant durability improvements over plastic alternatives.
- Long Wheelbase and Wide Track for Stability — With a 547mm overall length and 355mm wheelbase combined with a 450mm front and rear track width, the KRATON 4S delivers exceptional straight-line stability at speed. The long wheelbase is key to maintaining sure-footedness during hard bashing over dirt, and the wide track prevents tipping on aggressive cornering.
- Fully Assembled and Ready-to-Run — This brushless RC monster truck comes completely factory-assembled, finished, and trimmed, with all electronics factory-installed and calibrated. Simply charge your compatible LiPo battery, insert AA batteries into the transmitter, and you're ready to blast — ideal for buyers who want a ready-to-run RC car without complicated assembly.
- 17mm Aluminium Wheel Hexes — These precision CNC-machined red anodised hubs increase durability and provide authentic ARRMA styling. The larger hex size improves strength under aggressive driving conditions and makes wheel changes faster and easier.
- dBoots COPPERHEAD 2 LP Vented Tyres — These high-quality rubber tyres feature an aggressive, chunky tread pattern designed to find solid grip almost anywhere. The vented low-profile design provides excellent durability during extended bashing sessions and performs consistently across multiple terrain types.
- Spektrum SLT3 2.4GHz 3-Channel Transmitter and Dual Protocol SR315 Receiver — The included radio system operates on 2.4GHz frequency with fast response SLT protocol and improved grip and trigger feel. The SR315 receiver supports dual protocol compatibility (SLT and DSMR), offering flexibility and the option to upgrade to additional Spektrum transmitters in future. SMART telemetry is compatible in DSMR mode with the Spektrum dashboard app.
- Long Oil-Filled Aluminium Shocks — The suspension incorporates aluminium shock bodies for improved durability and heat dissipation, with long travel design for plush action. Silicone O-rings provide supreme sealing against dirt and moisture, essential for a brushless RC monster truck that will face all-weather conditions.
- Double Wishbone Front and Rear Suspension — This proven suspension geometry provides predictable handling and excellent traction through corners, whilst the high shock towers allow for extended suspension travel for maximum bump absorption.
- Front and Rear Skid Plates — Tough composite skid plates protect the chassis where it matters most, absorbing impact from rocks, roots, and other obstacles encountered during off-road bashing sessions.
- Wheelie Bar with Rubber Tyres — The compact wheelie bar provides ultimate control during acceleration and stunt potential, helping prevent the truck from tipping backwards during aggressive launch.
- Integrated Servo Saver with 25T Spline — This protects the servo and steering linkage from damage during impacts, using a 25T spline fitment for compatibility with the updated servo system.
- Tough Wing Mount and 3D Profile Wing — The rear wing reduces high-speed lift and adds visual aggression, with a tough injection-moulded design that withstands impacts.
- Rubber-Shielded Bearings Throughout — Sealed bearing construction protects against dirt ingress and moisture, maintaining smooth operation during wet-weather or muddy terrain bashing.
- Modular Design Philosophy — ARRMA's signature easy-access design makes routine maintenance fast and simple. The power module is removable for quick tuning changes, and the grommeted windows allow easy access to motor screws without complete disassembly.
- Waterproof and Dustproof Electronics — Both the ESC and servo feature waterproof and dustproof design ratings, allowing confident bashing through wet grass, muddy tracks, and dusty terrain.
- 2-Year Limited Warranty — ARRMA backs this product with comprehensive warranty coverage, providing peace of mind for your investment in this 4S brushless speed monster truck.
Technical Performance
The KRATON 4S 4X4 BLX represents peak engineering in the affordable 4S monster truck class. Powered by the Spektrum FIRMA 3668 2400Kv brushless motor paired with the FIRMA 120A V2 Smart waterproof ESC, this platform achieves genuine 55+ mph top speed in optimum driving conditions with a 4S LiPo battery. The motor's beautifully etched aluminium can and 4-pole construction deliver smooth, consistent power delivery across the entire RPM range, whilst the integrated heatsink and dedicated cooling fan manage thermal output during sustained high-speed bashing. The ESC supports full 2S, 3S, and 4S LiPo compatibility, with user-programmable settings for punch, brake behaviour, BEC output, reverse speed, and motor timing — allowing precise tuning to individual driving style and track conditions.
The chassis is constructed from moulded composite material revised to accept the centre differential module whilst maintaining structural rigidity. The three-differential system (front, centre, and rear) works together to distribute power intelligently across all four wheels, with the centre diff specifically engineered to improve traction and cornering grip. Front and rear gear differentials feature proven steel internal gears (37T crown gear with 13T pinion, 2.85 internal ratio), delivering robust power transmission under extreme acceleration and impact. The final gear ratio stands at 12.48, carefully calculated to deliver the optimal balance between top speed and acceleration responsiveness.
Suspension architecture incorporates aluminium-bodied oil-filled shocks front and rear, each filled with 550cSt silicone oil for plush, consistent damping across varying terrain. The wide 450mm front and rear track width combined with the long 355mm wheelbase creates an exceptionally stable platform, whilst high shock towers permit generous suspension travel (57mm ride height specification) for bump absorption. The front and rear differentials use 10,000cSt silicone oil, whilst the centre differential (the critical new addition) uses ultra-viscous 500,000cSt oil for precise, controlled traction management. All suspension components feature adjusted turnbuckle links for fine-tuning ride height and suspension geometry.
The steering system employs the upgraded Spektrum S662 digital servo, delivering 17kg (236oz-in) of torque with 0.15 second response time at 60 degrees. This metal-geared servo features steel internal gearing with a 25T output spline, an alloy case centre for enhanced heat dissipation, and waterproof construction suitable for all-weather bashing. The servo integrates with the updated integrated servo saver featuring 25T spline fitment, protecting both servo and steering linkage from impact damage.
Powertrain features EXB all-metal gear differentials front and rear combined with EXB CVD extreme bash composite slider driveshafts and steel couplings, guaranteeing power delivery without compromise. The 17mm aluminium wheel hexes are CNC-machined and red anodised, fitted with dBoots COPPERHEAD 2 LP vented low-profile tyres (156mm diameter / 3.8 inches) mounted on medium-compound inserts for aggressive multi-terrain grip. The tyres' aggressive chunky tread pattern provides consistent traction whether bashing through grass, over dirt tracks, or across paved surfaces.
Electronics include the Spektrum SLT3 2.4GHz three-channel transmitter and SR315 receiver (dual protocol version supporting both SLT and DSMR protocols). The receiver is SMART telemetry compatible in DSMR mode via the Spektrum dashboard app, and features proven fast response characteristics with outstanding radio range. All connectors employ IC5 specification (EC5 compatible), ensuring reliable power delivery. The truck's overall weight without battery is 4.2kg, with maximum battery dimensions of 156 x 51 x 48mm accommodating 2x2S, 3S, or 4S hardcase LiPo batteries with minimum 5000mAh capacity and 35C continuous discharge rate specification.
What's in the Box
- ARRMA KRATON 4X4 4S V2 BLX Speed Monster Truck RTR, Green (fully assembled and ready-to-run)
- Spektrum FIRMA 120A V2 Smart Brushless Waterproof ESC
- Spektrum FIRMA 3668 2400Kv Brushless Motor with integrated heatsink and cooling fan
- Spektrum S662 Metal-Geared Digital Servo (17kg torque, 0.15s response)
- Spektrum SLT3 2.4GHz 3-Channel Radio Transmitter
- Spektrum SR315 3-Channel Dual Protocol Receiver
- IC5 Loop connector (for use with single 3S or 4S battery pack)
- Multi Tool and Hex Wrenches (2.0mm and 2.5mm)
- 4x AA Alkaline Batteries (for transmitter)
- Comprehensive Instruction Manual
What You Need to Complete
- LiPo Battery: Choose either 2x2S (5000mAh minimum, 35C minimum discharge rate), 1x3S (5000mAh minimum, 35C minimum discharge rate), or 1x4S (5000mAh minimum, 35C minimum discharge rate) hardcase LiPo battery. Maximum battery dimensions are 156 x 51 x 48mm.
- Compatible LiPo Battery Charger: A charger capable of balancing and charging your chosen LiPo battery configuration at the appropriate cell count and discharge rate.
- LiPo Safe Charging Bag or Safety Sack: Essential for safe LiPo storage and charging to prevent fire risk.
Frequently Asked Questions
- Is the ARRMA KRATON 4S centre diff a genuine improvement over earlier versions without centre differential? — Yes, absolutely. The new oil-filled aluminium-cased centre differential represents a substantial handling upgrade, providing significantly improved traction and cornering grip across all surface types. The centre diff distributes torque intelligently between front and rear axles, reducing wheel spin and improving stability during high-speed cornering. This makes the truck noticeably more controllable when pushing 55+ mph and more predictable through technical terrain.
- What is the top speed of the KRATON 4S, and what battery do I need to achieve it? — The KRATON 4S is capable of 55+ mph top speed in optimum driving conditions when powered by a 4S LiPo battery. To achieve this speed, you'll need a 4S hardcase LiPo battery with minimum 5000mAh capacity and 35C continuous discharge rate. Running on 3S LiPo will deliver somewhat lower speeds, whilst 2x2S configuration will provide moderate performance suitable for learning and casual bashing.
- Is this ready-to-run monster truck suitable for beginners? — Yes, the KRATON 4S is an excellent choice for buyers progressing from slower 3S bashers to serious 4S performance, or for those starting their RC hobby with a quality brushless platform. It arrives fully assembled and ready-to-run with a complete three-channel radio system included. The included transmitter features 50% and 75% throttle mode options for beginners, allowing you to limit power output whilst learning. However, be aware that 55+ mph is genuinely fast — beginners should start with 3S LiPo power and progress to 4S as driving skills develop. The truck's long wheelbase and wide track provide excellent straight-line stability, making it forgiving for newer drivers.
- What battery connector does the KRATON 4S use, and is it IC5 or EC5? — The KRATON 4S uses IC5 connectors throughout, which are included on the ESC and motor. EC5 connectors are compatible with the IC5 system, providing flexibility if you already own EC5 batteries. The package includes an IC5 loop connector specifically for use with single 3S or 4S battery packs, allowing convenient charging and removal without modifying the truck's wiring.
- Can I use this brushless RC monster truck in wet conditions or muddy terrain? — Yes, absolutely. The electronics are rated as waterproof and dustproof, with sealed bearings throughout for dirt protection. The revised chassis includes an integrated dirt drain system, wishbone dirt guards protecting rear driveshafts, and taller side guards for additional protection. However, whilst the electronics can handle moisture, you should still rinse and dry the truck after muddy sessions and periodically check bearings and moving parts for dirt accumulation.
- What differentiates the KRATON 4S from similar 1/10 scale 4S monster trucks? — The KRATON 4S's defining features are its new centre differential system (providing superior traction control), the revised composite chassis engineered specifically to accommodate the centre diff module, and the updated Spektrum brushless electronics package (FIRMA 120A V2 ESC and higher-torque S662 servo). Additionally, the modular design philosophy makes maintenance easier than many competitors, and ARRMA's proven reliability record and engineering expertise ensure quality you can trust.
- How difficult is maintenance and routine upkeep on the KRATON 4S? — Very straightforward. ARRMA's signature modular design keeps maintenance simple — the power module is easily removable for tuning, and grommeted windows allow access to motor screws without full disassembly. The revised chassis with integrated dirt drain and protection systems reduces the frequency of deep cleaning required. Routine maintenance involves brushing off dirt after each session, checking bearings for smooth operation, and periodically refreshing differential and shock oils if running in particularly muddy conditions.
- What is the warranty coverage for the KRATON 4S, and what does it include? — ARRMA provides a 2-Year Limited Warranty covering manufacturing defects in materials and workmanship. This gives you significant peace of mind for your investment, though warranty terms and exclusions apply (typically excluding damage from crashes, improper maintenance, or abuse). Consult the included instruction manual for complete warranty terms.
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 ARRMA 1/10 KRATON 4S 4X4 BLX Centre Diff Speed MT (Green) C-ARA4408V2T4 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.
