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The Chassis (Japanese: シャーシ, Shāshi) is one of the main components of a Mini 4WD car.

How it works

The chassis acts as the main frame for the Mini 4WD car. There's the bumper on the front, side guards on the center-sides and rear stay on the rear for roller and mass damper setups. Inside the chassis, it contains several important components, including motor, gearing, batteries, bearings, driveshafts and battery terminals. Internal layouts and component placements are usually varied depends on the chassis.

On most Mini 4WD chassis, the motor was usually placed onto the mid-rear section, thus giving the rear-motored Mini 4WD car the 42/58 front-to-rear center-of-weight. There are exceptions, however, as some chassis has the motor placed onto the front (i.e. FM-A Chassis) or onto the middle (i.e. MA Chassis). On some chassis, motor and/or battery compartment can be accessed from under the chassis by removing the underpanel(s).

Over the course of Mini 4WD racing history, designs of the chassis has gradually evolves. Newer chassis has matured chassis structure, lower center-of-gravity, widened bumper and rear stay, and has the POM-made plastic bearings equipped.

On the MS Chassis, the only module-like chassis even existed, has the separate nose, center, and tail units that can be swapped individually, allowing better maintenance.

Racer can reduces the weight of the chassis or making the chassis more flexible by removing part of the chassis structure, allowing the wheels to stick to the road surfaces most of the time. However, this customization may have negative side-effects if not done properly.

Power loss and breakage

On circuits with a lot of ups and downs, the chassis may flexes while passing through those non-flat-surface sections. If a Mini 4WD car's chassis flexes too much, it may causes power losses due to frictions within the drivetrain as moving part of the drivetrain components are touching the chassis's drivetrain chambers as well as the gears being pushed too tight. In additions to this, the teeth on the gears may become damaged in a worst-case senario. This is more apparent with chassis that has weak chassis structure or has too much chassis structure removed in the weight reduction modifications done incorrectly.

In additions to this, weak structure or inproperly weighted-shaved chassis may face another problem: Breakage. Since the chassis has to receives impacts from landing and has to being pushed upward (depends on the circuit), those chassis will eventually breaks.

The solutions to both problems is either the use of the more rigid chassis or the use of reinforced chassis, or both. Newer chassis like AR Chassis, MA Chassis and FM-A Chassis has more rigid chassis structures compare to the prior chassis. Reinforced chassis were usually sold as limited GUPs, but some general Mini 4WD kits may includes them as well.