SPM Firma 5687 1100KV 4-Pole Brushless Motor, 8mm shaft M-SPMXSM4200

Overview

The Spektrum Firma 5687 1100KV 4-Pole Brushless Motor is a powerhouse engineered specifically for 1/5 scale RC bashers and monster trucks that demand extreme performance. This is not a beginner's motor — it's purpose-built for experienced RC enthusiasts who want to push their vehicles to the absolute limit with 8S LiPo batteries. The Firma 1100KV delivers a staggering 7900 watts of output power, making it one of the most capable motor options available for large-scale surface RC vehicles in the UK market. Whether you're running an ARRMA Kraton 8S EXB, Outcast 8S EXB, or similar high-performance 1/5 scale bashers, this motor provides the torque, speed, and durability needed to dominate any terrain.

Built with precision engineering and premium materials, the Firma 5687 features a robust CNC-machined aluminium housing that optimises heat dissipation during extended high-load operation. The motor's inrunner configuration combined with its 4-pole sintered rotor design ensures consistent torque delivery and smooth throttle response even under extreme acceleration. With an efficiency rating of 86% and a maximum continuous current of 95 amps, this brushless RC motor maintains thermal stability whilst delivering sustained power — essential for serious bashers who refuse to compromise on performance. The Safe-D shaft with c-clip locking point prevents pinion gear slip, adding another layer of reliability to your drivetrain setup.

For RC enthusiasts in the UK looking for a brushless motor that can handle 8S LiPo power and deliver genuine performance upgrades to their 1/5 scale RC monster trucks and bashers, the Firma 5687 1100KV is the recognised choice among competitive RC drivers and weekend warriors alike.

Key Features

• 7900 watts output power — This exceptional power delivery ensures your 1/5 scale RC basher has the muscle to accelerate hard, climb steep terrain, and maintain top speed even under heavy throttle, making it ideal for speed runs and high-performance bashing sessions.
• 4-pole sintered rotor design — The high-quality 4-pole construction provides a superior power-to-weight ratio and more efficient energy conversion than lower-pole count alternatives, resulting in stronger low-end torque and higher top-end RPM headroom.
• 1100KV rating optimised for 8S LiPo — This specific KV value is perfectly calibrated for 3-8S LiPo battery compatibility, delivering the ideal balance between torque and speed without over-revving or losing grunt, making it versatile across various voltage configurations.
• CNC-machined aluminium housing — The precision-engineered housing improves heat dissipation during sustained operation, keeping motor temperatures in check during intense driving sessions and extending the lifespan of internal components.
• Hardened steel 8mm output shaft — The oversized 8mm diameter shaft provides exceptional mechanical strength and stability with large pinion gears and heavy-duty drivetrain components, preventing flex and shaft failure under extreme loads.
• Safe-D shaft with c-clip locking point — This intelligent design feature prevents pinion gear slip during hard acceleration or impact, protecting your drivetrain and eliminating frustrating mid-race mechanical failures.
• High-purity copper windings — Insulated windings crafted from premium copper reduce electrical resistance, improve efficiency, and ensure reliable power delivery with minimal losses during operation.
• Precision ball bearings — High-quality bearings provide smooth rotation, reduce friction, and contribute to the motor's overall durability and longevity even in dusty or demanding off-road conditions.
• 6.5mm gold-plated bullet connectors pre-installed — These high-quality connectors are corrosion-resistant and ensure reliable electrical contact with your ESC, reducing voltage drop and improving overall system efficiency.
• 86% efficiency rating — This excellent efficiency means more of your battery's energy translates into motion rather than heat, extending runtime and reducing thermal stress on the motor and ESC during extended use.
• 95 amps maximum continuous current — The motor can sustain demanding loads for extended periods without thermal throttling, making it suitable for prolonged high-performance driving without needing to let it cool between runs.
• Sensorless inrunner configuration — The sensorless design simplifies installation whilst the inrunner layout maximises torque in a compact form factor, ideal for vehicles with space constraints or direct motor mounting.
• Perfectly matched for Firma 160A Smart ESC — Spektrum has engineered this motor to work flawlessly with the Firma 160A Smart ESC, ensuring optimal performance calibration and enabling smart telemetry monitoring on compatible systems.

Technical Performance

The Spektrum Firma 5687 1100KV represents the pinnacle of brushless motor technology for 1/5 scale RC vehicles. At 3.4 inches (86mm) in length with a 2.2-inch (56mm) outer diameter, the 5687-size format strikes the perfect balance between power density and heat management. The motor weighs 31.5 ounces (893 grams), making it suitably substantial for high-torque applications without being prohibitively heavy. The CNC-machined aluminium construction isn't merely aesthetic — it provides superior thermal conductivity compared to plastic alternatives, critical for maintaining optimal operating temperatures when drawing 95 amps continuously at 11.1-29.6V (3-8S LiPo compatibility). The hardened steel 8mm shaft with its 0.87-inch (22mm) length provides a generous engagement area for pinion gears whilst the Safe-D design prevents the most common failure mode in high-power RC drivetrain systems. With a resistance rating of just 0.0041 ohms, electrical losses are minimised, contributing to that impressive 86% efficiency figure. At 15V input, the motor produces 16,500 RPM per volt, generating extraordinary rotational speeds when paired with higher cell count batteries. The constant wattage rating of 3000W or more ensures the motor delivers sustained power output under continuous load. For comparison to other brushless RC motors in this class, the Firma 1100KV sits between the lower-KV high-torque variants and higher-KV speed-focused designs, making it the pragmatic choice for drivers who demand both acceleration and top-end performance from their 1/5 scale RC basher.

What's in the Box

• Spektrum Firma 5687 1100KV 4-Pole Brushless Motor with 8mm hardened steel shaft
• Pre-installed 6.5mm gold-plated bullet connectors
• Motor with integrated wire leads (190mm/7.48 inches in length)

What You Need to Complete

• 160A brushless ESC (Spektrum Firma 160A Smart ESC recommended for optimal performance and telemetry integration)
• 3-8S LiPo battery pack (higher cell count delivers more power — 6S or 8S recommended for maximum performance)
• RC vehicle chassis compatible with 1/5 scale motors (such as ARRMA Kraton 8S EXB or Outcast 8S EXB)
• Motor mounting hardware specific to your vehicle platform
• Pinion gear sized appropriately for your chosen gearing ratio and desired speed/torque balance

Frequently Asked Questions

• Is the Spektrum Firma 5687 1100KV motor suitable for beginners or only experienced RC drivers? — This is definitely an advanced-level motor designed for experienced RC enthusiasts. The 7900-watt output and 8S LiPo compatibility require proper understanding of brushless motor systems, ESC programming, and battery safety. Beginners should start with lower-powered brushless alternatives or sensored motors with simpler setup requirements. If you're new to RC and considering this motor, we recommend consulting with our team at RC Model Shop first to ensure you have the supporting components and knowledge to use it safely and effectively.
• What battery does the Firma 5687 1100KV need and how long will it run? — The motor is compatible with 3S, 4S, 5S, 6S, 7S, and 8S LiPo batteries (11.1V to 29.6V input range). For maximum performance, 6S or 8S setups are recommended. Runtime depends entirely on your battery's mAh capacity and your driving style — aggressive full-throttle bashing will consume power quickly, whilst more moderate driving extends runtime significantly. A typical 5000mAh battery might provide 15-25 minutes of mixed driving with this motor, though this varies considerably based on terrain, vehicle weight, and throttle usage.
• Can I use this motor with a standard brushless ESC or does it require the Firma 160A? — Whilst the Firma 5687 is perfectly matched to the Firma 160A Smart ESC, it will work with any quality 160A or higher-rated brushless ESC capable of handling sensorless inrunner motors and 3-8S LiPo batteries. However, using the recommended Firma 160A Smart ESC ensures optimal performance calibration and enables intelligent telemetry monitoring on compatible receiver systems. For best results and warranty support, we strongly recommend the matched pairing.
• What is the difference between the Firma 1100KV and other Firma motor variants like the 800KV or 2200KV? — The KV rating determines the motor's RPM per volt relationship. The 800KV variant produces lower RPM but higher torque, making it better for extreme crawling or maximum pulling power. The 1100KV (this model) balances torque and speed, making it the ideal all-rounder for mixed bashers and monster trucks. The 2200KV produces higher RPM and lower torque, biased towards pure speed. Choose based on your intended use: 800KV for torque-focused bashing, 1100KV for balanced performance across all driving styles, or 2200KV for speed-focused applications.
• Does the Firma 5687 motor come sensored or sensorless, and does this matter? — The Firma 5687 1100KV is a sensorless design, which means it relies on back-EMF feedback rather than magnetic sensors to commutate. This simplifies the motor construction and reduces complexity, though sensorless motors can be slightly rougher at extremely low speeds compared to sensored variants. For 1/5 scale bashers running at typical speeds, sensorless operation is more than adequate and actually preferred by most serious drivers due to reduced component count and improved reliability.
• How does the Safe-D shaft help protect my RC vehicle's drivetrain? — The Safe-D shaft includes a c-clip locking point that provides a mechanical lock for your pinion gear, preventing the gear from sliding back onto the motor shaft during hard acceleration or collision impacts. This is crucial for maintaining drivetrain integrity in high-powered systems where sudden torque spikes can cause pinion slippage, leading to loss of power transmission or gear damage. Without this feature, you might experience frustrating mid-race mechanical failures.
• What size is the Firma 5687, and will it fit my RC vehicle? — The motor measures 3.4 inches (86mm) in length with a 2.2-inch (56mm) outer diameter — this is the standard 5687 size commonly used in 1/5 scale bashers and monster trucks. Compatibility depends on your specific vehicle platform, but it's designed to drop into vehicles like ARRMA's 8S lineup. Always verify motor mounting compatibility with your chassis before purchasing, or contact our team at RC Model Shop to confirm fitment for your particular model.

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 Spektrum Firma 5687 1100KV 4-Pole Brushless Motor, 8mm shaft M-SPMXSM4200 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.

We want to make sure your delivery goes smoothly, so here are some important details about our service:

• For orders above £120, we offer delivery to most mainland UK addresses. For orders under £120, we can still deliver to Northern Ireland and the outlying isles, as long as the item can be sent by Royal Mail, weighs less than 30kg, and fits within 61cm × 46cm × 46cm. Some highland and remote areas may carry an extra delivery charge as couriers often apply surcharges in these locations. If you live in one of these areas, feel free to contact us before ordering so we can confirm the delivery options and costs for you.
• Most of our products include delivery in the price. If your order is under £90, a small delivery fee will apply but do not worry this will always be clearly shown at checkout before you complete your purchase.
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• If your order includes items with different dispatch times we will normally wait and send everything together once all items are in stock. If one of the items is going to take a while we will give you the choice either wait for everything to arrive or let us send the available items now and deliver the rest later. It is up to you.
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• For customers in Inverness and other parts of the Scottish Highlands deliveries can take up to 2 working days even if you select next day delivery as couriers do not currently offer a guaranteed next day service to those areas.

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