Mini 4WD

History

In 1980, a mini 4WD series of vehicles called Stomper 4x4, were invented by Adolph Goldfarb and produced by Schaper. A multitude of replicas produced by other companies led to lengthy lawsuits, and eventually the company sold the product to Tyco, after which, sales declined.

In 1982, 4WD Mini Racer (ミニ四駆) was produced by the Japanese company Tamiya as a powered variant of their plastic automobile model kits. Since then racing and tuning up mini 4WD cars have become a hobby for people across the world.

Beginning in 1982, Tamiya mini 4WD kits were sold by Model Rectifier Corp (MRC), the exclusive U.S. Distributor of Tamiya. The kits were manufactured in Japan while the boxes were printed in Canada. The kit parts were then packaged into the boxes in Edison, New Jersey, USA. MRC continued to sell Mini 4WD kits until at least 1990, which may be the year their Tamiya license expired.

In 1989, Tamiya commissioned Shogakukan, a Japanese publishing company, to produce two anime TV series based on the Mini 4WD cars: Dash! Yonkuro by Zaurus Tokuda, Bakusō Kyōdai Let's & Go!!, Bakusou Kyoudai Let's & Go WGP in 1996, Bakusou Kyoudai Let's & Go MAX, and finally Bakusō Kyōdai Let's & Go!! WGP: Bousou Mini 4WD Daitsuiseki.

Also in 1989, Tamiya America was established in the United States and replaced MRC as the officially licensed distributor for Tamiya, in that country. Headquartered in Irvine, California, Tamiya in the United States holds USA Mini 4WD Championships at Marukai Corporation U.S.A. in Gardena, California.

In 1999, Tamiya Japan temporarily suspended the Great Japan Cup world championships for Mini 4WD racers.

By the 2000s, at least twenty-eight (28) other companies had ventured into the Mini 4WD market, and famously included Tokyo Marui, Kyosho, Academy, Auldey Animation and Toys, Circuit no Ōkami, Aoshima Bunka Kyozai, Matchbox (brand), Revell, Hot Wheels, Tonka, Hasbro, and Bandai. Many of them introduced their own lines of mini cars, while some produce counterfeit replicas of Tamiya cars.

Beginning again in 2006, Japan holds National Mini 4WD Championships in Spring, Summer and Autumn each year and by 2012 Mini 4WD is popular in more countries including Thailand, Singapore, South Korea, Canada, Germany, Italy, Russia, India and China.

Guinness Book of World Records now shows the longest mini 4wd track in the world was set in Japan in October 2010 at 523.61 meters which record was quickly broken in Thailand in March 2011 at 1,074.5 meters at the Central World Mall sponsored by Panasonic. Three years later, on 1 February 2014, a new record was created at 1,188.67 m (3,899 ft 10.03 in), at Omiya Elementary School in Hitachioomiya, Ibaraki, Japan.

Generation I (Schaper)

Stomper 4x4s was the first official mini 4wd, created on February 14, 1980, by Adolph Eddy Goldfarb and sold by Schaper Toys. These toys were battery-powered vehicles that ran on a single AA battery and featured four-wheel drive. They were driven by a single motor that turned both axles. Of the first vehicles were a Ford Truck and a Chevrolet Truck.

Generation II (Tamiya)

In 1982, Mini 4WD was produced by Tamiya. These toys were battery-powered vehicles that ran on a pair of AA battery and featured four-wheel drive. They were driven by a single motor that turned both axles. Of the first vehicles were a Ford Truck and a Chevrolet Truck.

Generation III (Tamiya)

Generation IV (Tamiya)

Generation V (Tamiya)

Generation VI (Tamiya)

Generation VII (Tamiya)

In 2003, Tamiya produced the R/C Mini 4WD series starting with Subaru Impreza WRC 2002 and the TR-1 chassis, a chassis that runs with a receiver unit and a single-button radio controller. As the cheapest alternative to actual R/C cars and slot cars, the receiver unit is removable to let the car freely run on the track with just the motor and batteries, there were also car component kits and unique tune-up parts produced. However, the R/C Mini 4WD cars' popularity were not widespread after its introduction and Tamiya continued making free-running Mini 4WDs.

Generation VIII (Tamiya)

Generation IX (Tamiya)

Special/Limited Edition Mini 4WD models (Tamiya)

Mini 4WD Design

In a standard 4WD design, the separate four wheels are allowed to rotate at different speeds through the use of differentials. This is important for cornering to eliminate binding. In a Mini 4WD, this is not a standard design and is only achieved through optional one-way wheel sets. Thus, the standard Mini 4WD utilizes a direct drive to all 4 wheels even around corners. Chassis' are designed to hold the motor and batteries in differing arrangements. There are sideways motors positioned in the rear. There are sideways motors positions in the front. There are in-line motors positioned in the middle. Rear and Front position motor designs position batteries side by side in the front or rear of the motor placement. Middle position motor designs position the batteries straddling either side of the motor. Rear and front position motor designs utilize a propeller rod extending from the main motor gear box that drives both the front and rear axles. Middle position motor design powers both the front and back wheels through separate gear boxes eliminating the need for such a propeller rod.

Chassis' are designed with front bumpers, optional side and rear bumpers designed to hold guide rollers that interact with the track's 58mm high walls.

The body is designed from hard plastic or soft, transparent Polycarbonate, known by the trademarked names Lexan, for special or limited editions, which attaches with a catch-type lock at the back of the car, distinguishes one model from another.

Motors

There are three specifications that characterize all motors: RPM, torque, and power-consumption. RPM is the speed the motor provides, and the torque its strength. Higher the RPM means higher maximum speed ; Higher torque gives more acceleration and allows the car to better withstand the difficulties of climbing slope or running through turns.

Gears

Different types of gears have different ratios of rotation of the motor and the wheel, and they include "Super Speed" (3.5:1), "High Speed" (4:1), "Speed" (4.2:1), "Standard" (5:1), and "Special" (ratio varies but are usually 6.4:1). Higher the ratio, better the acceleration rate and torque; lower the ratio, better the maximum speed.

Tires and Wheels

It is recommended that, among the different wheels available, the compatible ones must maintain the same size as those from the assembly packet. Smaller the diameter, more stable it is, as the car's center of gravity is lowered. Although one can easily assume that a larger wheel suits a faster car the best, this is not at all the case. Large wheels are for cars with high gear ratio (i.e. "5:1") and weak motor; small wheels are for cars with low gear ratio and strong motor. Wider wheels allow for more stability but suffer from friction, and, thus, speed loss; thinner wheels are intended for speed, but the car could be susceptible to flipping off the track.

There are four types of different wheels: normal plastic, one-way, aluminum, and lock-nut. Normal plastic wheels are fine, but they are not adequate for really fast cars. They become loose after disconnecting them from the axle several times. Additionally, they create drag when the car going through turns as the axle locks the two wheels at same speed, since the outer wheel must cover more distance than the inner wheel (relatively to the turn of the course). One-way wheels allow either side to roll faster than the other when turning, and minimize the speed loss in turns. Aluminum wheels are very light, sturdy, and best for speed. Some aluminum wheels have preventive measures against loosening with the axle. However, lock-nut wheels are the best in preventing the cars from losing the wheels during a run.

There are four types of tires: rubber, sponge, reston, and semi-pneumatic. Rubber tires come as standard with the Mini 4WD, and, although it has good grip, it is heavy and is susceptible to slipping on wet surfaces. The alternate solution to the rubber tire are the reston or sponge tires, which are very light, have good grip, and are better suited for rainy days. Yet, these get dirty easily, and they tend to exhaust the motor.

Bumpers

Bumpers are usually found at the opposite ends of the mini 4WD. Upgrading the bumper becomes a necessity as the mini 4WD is modified to run faster than what the stock kit usually runs. The faster the car, the more the car needs down force to counter the decrease in stability. The stock chassis+bumper combination does have a tendency to bend, causing the rollers to run at angles and may make the mini 4WD fly off the course. Aluminum, fiberglass, or carbon fiber plates are usually installed as after-market upgrades to prevent this from occurring. Another possible upgrade are the screws that keep the rollers to the bumper. Tamiya offers stainless steel ones.

Most after-market upgrade plates are usually wider than the stock bumper, and they facilitate the installation of "side extension" plates that make the front profile of the mini 4WD even wider.

Roller and Race Categories

Roller is the wheel that rests on either end of the mini car's bumper and glides against the wall of the course. This allows the car to change direction and maintain stability. Conventional roller will do fine on a car with average speed, but, on a much faster car, aluminum or ball-bearing rollers must be purchased to acquire additional downforce and stability. These rollers do not tilt in angle as the conventional plastic rollers, and, therefore, have better chance in preventing the car from flinging off the course. Ball-bearing rollers have small metal balls around the internal ring, on which the roller spins, in order to minimize friction. Some rollers consist of two rollers on a pole -one at the base and other at the top-, so that they may offer the best stability. There are three types of roller arrangements. The first one is in which all rollers are same-sized, and this is for straight courses. The second arrangement, in which larger rollers are stationed in the front, is less stable when running through corners but minimizes speed losses; the third arrangement, in which smaller rollers are put in the front, is more stable when running through corners but the car is more susceptible to speed losses as it pushes into the wall.

3 types of racing categories for Mini 4WD are Technical, Speed-Technical and Drag Racing.