Original Year
# of pieces
Cars & Trucks: Buggies
Steering, V-6 engine
Rear suspension with dual modes
Other Views

8428/8432 Concept Car or

Turbo Command

iso revolve
Click the image to download the LDraw file of this model.
Model by marco9999

The 8428 Concept Car is a very unusual model.  Apart from the unique wheels, this model is visually unique because the entire cage assembly is made from angled connectors, axles, and flexible tubing including the new ribbed hoses.  But most special of all is the suspension system. Only the rear axle is suspended, but it uses an extremely clever mechanical system to switch between two different suspension geometries.

This model was released under two different numbers: 8428 and 8432.  The latter set included exactly the same model, but also included a CD-ROM.  The CD had early digital instructions and a racing game using the buggy.  Sadly, like other early LEGO® software, it is largely unusable on modern computers and even at the time was supported only on Windows PCs.  I no longer have a copy of this software (or a computer capable of running it), so no further information is presently available.

Because of similar design details including matching wheels and width, this model can be towed perfectly by the 8462 tow truck.


The front wheels can be steered using an overhead "hand of god" control driving a set of 12 tooth bevel gears.  A pinion gear mates with a rack and drives the steering arm back and forth.

This model also features a working steering wheel at the driver's position which is linked to the steering drive axle in parallel.

The steering lock on this car is very small leading to a very large turning radius.
steering    steering
Click for an animation of the steering in motion.
The V-6 engine is made from transparent engine elements and is driven by the rear wheels.  The differential ring gear and the crown gear (see computer image) both have 24 teeth therefore the engine gear ratio is 1:1.  The u-joint is necessary to allow the angle of the drive shaft to change with suspension motion.
engine    engine
Click for an animation of the engine in motion.
The live rear axle uses a differential gear which incorporates a built in 16 and 24 tooth ring gear.  The differential is made to house 3 of the 12 tooth bevel gears.  One is on each axle, and one planet gear in the middle allows the axles to turn at different rates.
diff    engine
Click for an animation of the differential in motion.
This model has rear suspension with multiple geometries: high and low.  Both have the same travel but the vehicle ground clearance is quite different with each.  The two photos at the right show the difference.  A very clever mechanism (which is very difficult to describe) is used to switch between the two.  A blue crank just behind the roll cage is used to make the switch.  The computer image shows 4 axles in red which are the ground points.  The horizontal shock absorber is used to lock the mechanism into either position when the cams travel over center.  The black L-shaped liftarms are the shock supports and end up nearly vertical but opposite in either position, and in either case are against a hard mechanical stop to support the load.  This leads to an overall change in ride height of about 4 studs.
suspension    suspension

Click for an animation of the low suspension in motion.
Click for an animation of the high suspension in motion.
Wheels and Tires
This set uses 4 of the futuristic metallic silver wheels with hard runner tires.  Curiously, the front wheels are installed with the deep dish facing outward which means that the kingpin axis is outside the wheel.

Other Views

Side View
side view
Top View
top view
Front View
front view
Back View
back view
Computer Render

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