Marui Big Bear Datsun
Early 1/12-scale monster truck kit from Tokyo Marui.
The Marui Big Bear Datsun (MT-59-RC-4) is a 1/12-scale electric radio-controlled monster truck from Tokyo Marui, a Japanese company known for hobby products and airsoft guns. Released in 1984 as a mail-order kit, it came without batteries, a radio, or a charger. Its design included a plastic tub-style chassis, a Mabuchi M480-RS motor, mechanical speed control, and a live axle rear suspension instead of an independent setup. The wide, chevron-treaded tires made up most of the suspension, with simple coilover shock absorbers providing limited travel. Coil springs also held the front bumper and absorbed impacts. The body was a detailed styrene Datsun pickup with a driver figure and "Big Bear" decals. Its low cost, easy assembly, and strong factory and aftermarket support helped grow the early RC hobby. However, stiff competition from Tamiya and issues with brittle plastic led Tokyo Marui to exit the hobby market by the end of the 1980s. In Australia, the Big Bear was sold as a complete kit that included a radio transmitter, batteries, and a charger. The first version (v.1) had differential gear problems. It shared gearboxes and gears with the Marui Jeep CJ and Toyota Landcruiser kits, using two large bevel gears and 48-pitch metric gears. The special black M480-RS motor and large tires created extra load, causing the differential gears to break or overheat and melt. Marui released a replacement part, the "#048 - Strengthened Differential Gear Set," which featured a tri-bevel differential, larger 32-pitch gears, and changed gear ratios. This set appeared in the re-release (v.2), along with a heat sink plate between the gearbox halves. The new ratios added torque, making the truck wheelie more easily but slowing it down. Marui also swapped the original motor for an RS540-SH motor and redesigned the mechanical speed controller with covered contacts to prevent contamination. Specifications: 1/12 scale, ABS resin tub chassis, rear-wheel drive with differential, independent front trailing arm and live axle rear suspension, simple coilover shocks, Mabuchi RS-540 (v.1) or RS-540SH (v.2) motor, semi-pneumatic rubber chevron tires, catalog number MT-59-RC-4.
- Scale
- 1/12
- Chassis construction
- ABS resin tub-style
- Transmission
- Rear wheel drive with differential
- Suspension
- Independent front trailing arm and live axle rear suspension
- Shock absorbers
- Simple coilover
- Motor (v.1)
- Mabuchi RS-540
- Motor (v.2)
- RS-540SH
- Tires
- Semi-pneumatic rubber chevron
- Original marui catalog number
- MT-59-RC-4
Lore & Background
The Big Bear was originally sold only through mail order in 1984 as a kit without batteries, radio, or charger. Its body was a highly detailed styrene plastic Datsun pickup with a driver figure and 'Big Bear' decal set. The tires were wide, chevron-treaded implement-styled units that comprised the majority of the suspension, with simple coilover shock absorbers allowing limited suspension travel. Coil springs also held the front bumper in place and absorbed impact. Owners of the original version (v.1) experienced problems with its differential gears, which were shared with the Marui Jeep CJ and Marui Toyota Landcruiser kits. The special black M480RS motor and large tires created increased load, causing the differential gears to break or heat up and melt. Marui released a special replacement part '#048 - Strengthened Differential Gear Set' with a tri-bevel differential, larger 32 pitch gears, and a change to the gear ratios. This new differential gear set found its way into the re-release of the Big Bear (v.2) coupled with a new heat sink plate between the gearbox halves. There were some draw backs to the new gears; The added torque of the new gear ratios made the truck do wheelies more easily, and made the truck a little slower. In addition to replacement gears and heat sink, Marui replaced the original M480-RS motor with an RS540-SH motor, and a redesigned mechanical speed controller with covered contacts to eliminate contamination.
Reader's Guide
Because of its low cost, ease of assembly, and good factory and aftermarket support, the Big Bear played an important role in the early growth of the radio control hobby. Due to intense competition from Tamiya and somewhat brittle plastic, Tokyo Marui pulled completely out of the hobby market by the end of the decade. The Big Bear was sold in Australia as a complete kit, including radio transmitter, batteries, and charger. Many supporting manufacturers developed aftermarket parts specifically for this kit. The v.2 revisions addressed the differential issues but introduced drawbacks: the added torque of the new gear ratios made the truck do wheelies more easily and made it a little slower.
Design & Engineering Philosophy
The Marui Big Bear Datsun (MT-59-RC-4) was a 1/12-scale electric monster truck built around an ABS resin tub-style chassis with rear wheel drive and a differential. Front suspension used independent trailing arms, while the rear relied on a live axle arrangement. Shock absorption came from simple coilover units that offered limited travel, and the wide, chevron-treaded semi-pneumatic rubber tires actually carried much of the load-bearing and suspension work. Coil springs even doubled as the mechanism holding the front bumper in place while absorbing impacts. The body was a highly detailed styrene plastic Datsun pickup, complete with a driver figure and a "Big Bear" decal set. Power was delivered through a Mabuchi motor paired with a mechanical speed control. Originally distributed in 1984 strictly through mail order as a bare kit, it came without batteries, a radio transmitter, or a charger, leaving owners to source those components separately.
Market Impact & the Growth of RC Hobby
The Big Bear occupied a meaningful place in the early expansion of the radio control hobby. Its relatively low price point, straightforward assembly process, and the availability of both factory and third-party support made it an inviting entry point for newcomers to the hobby. In its home market, it was sold exclusively through mail order starting in 1984, while in Australia it was offered as a complete package that included the radio transmitter, batteries, and charger. Nevertheless, the competitive pressure from Tamiya, compounded by the somewhat brittle nature of the plastic components, proved difficult for Tokyo Marui to sustain. By the close of the 1980s, the company had withdrawn entirely from the hobby market, ending production of the Big Bear and its sibling kits. Even so, the truck's contribution to establishing RC as an accessible and popular pastime during that formative decade remains a notable part of the hobby's history.
The Differential Gear Crisis & the v2 Revision
Owners of the original v1 Big Bear quickly discovered a persistent weakness: the differential gears would either snap or overheat to the point of melting. The kit shared its gearbox and gear train with the Marui Jeep CJ and Toyota Landcruiser, relying on two large bevel gears and a 48-pitch metric set. The combination of the special black M480RS motor and the large tires generated loads that these gears were not engineered to withstand. Marui responded by engineering a strengthened differential (part number 048) featuring a tri-bevel layout, larger 32-pitch gears, and revised ratios. This upgrade, together with a heat sink plate sandwiched between the gearbox halves, a replacement RS540-SH motor, and a redesigned mechanical speed controller with covered contacts to prevent contamination, formed the foundation of the v2 re-release. The trade-off was that the increased torque made the truck wheelie more readily and slightly reduced its top speed.
Aftermarket Ecosystem & Community Longevity
The Big Bear was supported by a broad ecosystem of manufacturers who produced aftermarket parts designed specifically for the kit. Marui itself maintained a shared spare parts list that spanned multiple kits, including the Jeep CJ and Landcruiser, reflecting the commonality of components across their product line. The availability of both factory replacement parts and third-party modifications meant owners could repair, upgrade, and personalize their trucks well beyond the stock configuration. This depth of support, combined with the kit's accessible tub chassis and simple mechanical systems, made the Big Bear particularly well-suited to modification and experimentation. It fostered a community of hobbyists who continued to tinker with, upgrade, and maintain their trucks long after Tokyo Marui had exited the hobby market, extending the vehicle's practical life well past its original production run.
Frequently Asked Questions
What is the Tokyo Marui Big Bear Datsun?
It is a 1/12-scale electric monster truck kit made by Tokyo Marui, a Japanese company better known for airsoft and hobby goods. The model, designated MT-59-RC-4, pairs a Datsun-styled body with a tub-style ABS resin chassis.
What motor and drivetrain does the Big Bear Datsun use?
The first version was powered by a Mabuchi RS-540 electric motor that drove the rear wheels through a differential. Throttle control was handled by a simple mechanical speed controller rather than an electronic one.
How is the Big Bear Datsun's suspension set up?
The front end uses independent trailing arms, while the rear relies on a live axle paired with basic coilover shocks that offer only modest travel. The wide, chevron-treaded tires themselves absorb a large share of the impact, acting as part of the suspension.
What did the original 1984 kit actually include?
Sold as a mail-order package, the box contained the mechanical and electrical components but no battery pack, radio transmitter, or charger. Buyers were expected to procure those items on their own to get the truck running.
Why do RC collectors still talk about the Big Bear Datsun?
It is one of the earlier Japanese 1/12-scale monster truck kits, reflecting the simpler engineering of the mid-1980s with its tub chassis and live-axle rear. Fans appreciate it as a snapshot of how far the category has come since independent four-wheel setups and electronic speed controllers became standard.
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