The FM-A Chassis (Japanese: FM-Aシャーシ, Efuemuē Shāshi) is a Mini 4WD chassis to be released by Tamiya. It was officially unveiled in the 56th Shizuoka Hobby Show which was held from May 11 to May 12, 2017. It was first equipped with the Rowdy Bull Mini 4WD car.

The 'FM-A' stands for 'Front Midship Aero'.

General info

The FM-A Chassis is essentially a AR Chassis with the motor being placed onto the front, inherited most of the aero-dynamic and heat-dissipating design from the latter. Just like the AR Chassis, the new chassis features the multi-subframe chassis frame design, allowing it to surpass the likes of Super XX Chassis in terms of stiffness. (but not on par with the AR Chassis.)

Similar to the AR Chassis and MA Chassis, the front bumper and rear stay were extended and widened, allowing smoother cornering, better cornering stability and better parts attachment. The subframes and the integrated side-guards has multiple attachment holes on it, allowing better parts attachments. There's a optional, polyoxymethylene-made front skid bar that was attached under the front bumper (Attached using a pair of truss screws), provides frontal protection against the road surface and slows down the car on slopes. The removable, 2-hardpoint rear stay has the built-in skid shaped parts under it, allowing to not only slow down the car on the slope sections of the circuit, but also stabilize the car on landing.

By default, it has a pair of normal 13 mm ringless rollers attached on the front and a pair of the new, wide-height 13 mm rollers attached on the rear. The wide-height rollers on the rear provides better stability on cornering. It is possible to fit the 530 ball bearing into the wide-height rollers.

The A parts were molded in the low-friction POM (Polyoxymethylene) plastic, thus eliminates the brass bearing eyelets all together and improves the acceleration performance.

The batteries were held securely by a large, slide lock-type upper battery cover. Just like the AR Chassis, the batteries were placed lower to lower the center-of-gravity of the whole chassis. Battery clips from older chassis (Specifically, those from Zero Chassis. Super-1 Chassis, FM Chassis and Super-FM Chassis) are also compatible with the FM-A Chassis. The front underpanel can be removed and allows easy access to the motor. The bodyshell must be removed beforehand in order to access to the counter gear and battery compartments.

Despite the X-type terminal parts were being used in the new chassis, it has the newly-designed turn-type battery switch.

Although the chassis utilizes the orange crown gears just like the past front motor chassis, the 1.4 mm wide propeller shaft from the Super X Chassis and Super XX Chassis was used instead, thus minimizes the power loss.

In terms of overall performance, the FM-A Chassis has better acceleration, something that past front-motor chassis failed to do so. It also has adaptability thanks to its extensive attachment points and removable rear stay. As noted, however, its toughness is less than that of the AR Chassis's, and cornering performance is nonetheless the same as AR Chassis's.


Chassis frame

A parts

Chassis info

Chassis Data
Length 156 mm
Width 97 mm
Wheelbase 83 mm
Ground Clearance 2.5 mm
Driveshaft Length 60 mm
Compatible Gear Set(s) 5:1
Roller Down Thrust Angle 5
Terminal Type X-type
Weight Without batteries:
Chassis Stats
Toughness 4 FMAChassisStats
Acceleration 5
Cornering 4
Stability 4.4
Adaptability 5
Ease of Maintenance 4



  • It is the first new front-motor chassis since the Super-FM Chassis, released 21 years prior.
  • Most bodyshells designed for FM and Super-FM Chassis are compatible with the FM-A Chassis with no modification, while others require minor modifications in order to fit onto the new chassis.
  • It is the first Mini 4WD chassis to come with a front underguard by default.
    • It is also the first Mini 4WD chassis to come with a pair of new, wide-height rear rollers by default.
  • Whereas the AR Chassis and MA Chassis feature the non-removable rear stay, the FM-A Chassis instead has the optional, removable rear stay.
    • It should be noted that the FM-A Chassis is only compatible with rear roller stays that are using 2-hardpoint for attachment, meaning those that are using 1-hardpoint would not be compatible with the new chassis.
  • As with AR Chassis, the use of normal and purple pinion gear in the FM-A Chassis are strictly prohibted in race tournaments. In addition to this, the use of orange crown gears in the new chassis means that the use of carbon helical crown gears is prohibted, as it violates the race regulations.[1]


  1. Mini 4WD Grade-Up Parts Matching List (Gear sets) (Japanese)
Original series Origin · Comical · Wild · Cruiser · RV
Type series
Type-1 · Type-2 · Type-3 · Type-4 · Zero · FM · Truckin' · Type-5
Super series
(Super/Mighty, Fully Cowled/Aero)
Super-1 · Super-FM · Super TZ · Super X · VS · Super TZ-X · Super XX · Super-II
Mini-F series Mini-F
R/C Mini 4WD TR-1
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