Every 80’s kid first Technic Set
The 8860 Technic Lego set was only the second generation auto chassis, after the 1977 European release of the 853/956 Auto Chassis, which would be known in the US, in 1978 as the “Expert Builder” set.
The 8860 has a special significance for many Lego Technic enthusiasts, as well as myself, who were lucky enough to come into possession of this remarkable set.
Starting with the overall construction of the frame, the 8860 Auto Chassis is true to its name, as it’s designed to convey the look and functionality of a real four-wheel vehicle, minus a body exterior shell, and what I loved the most about this set was how simple, and yet sophisticated it was, in terms of mechanical parts and technology.
Functional Steering
The functional steering column used a standard 8-tooth pinion gear controlling the position of the wheels, according to the Ackerman Principle, by which “the inner wheel (closer to ICR) should steer for a bigger angle than the outer wheel in order to allow the vehicle to rotate around the middle point between the rear wheel axis.” according to this article by Science Direct. The end result for vehicles constructed in such fashion, is to avoid skidding when making a turn, and it’s a universal standard in real-life automotive technology, as well as for most toy vehicles that include functional steering.
Engine Block and Transmission
The amount of detail for such an early set, also included a functional engine block and transmission, simulating a 4-cylinder “boxer” engine, with a three-speed gear box.
One interesting fact about the transmission on the 8860 Lego set, was that the first gear was designed to be locked by default, due to the fact that the gear ratio is too low, which would have put a strain on the engine block at high speeds. Because of this reason, the instruction of this set recommended blocking the first gear position with a plate, to allow selection of the second and third gear only.
Suspensions
The suspensions on the 8860 Lego Technic set weren’t any less sophisticated than its engine block, and relied on twin hydraulics, supporting a cantilevered control arm. This system allowed the 8860 to accommodate a wider range of terrains.
While this system was considered rudimentary in the late 70s and early 80’s, this was historically the very first suspension system features in a Lego set of any kind.
Differential
Another unique aspect further characterizing the transmission and suspension system featured onboard the Auto Chassis Lego set, was the working differential, which was another first in Lego history. In order for the differential to realistically portray a working one, this set included a “planet gear”, a special piece designed to house three 14-tooth bevel gears, one for each axle, to allow different turning rates.
Adjustable Seats
It wouldn’t be a true Lego Technic set, if it didn’t include adjustable seats capable of reclining and sliding. The mechanism used to simulate adjustment for the two bucket seats was very simple but effective, with a spring-loaded ratchet and pawl, keeping the seats from falling back.
Big wheels
The 8860 Lego set also featured massive 24×43 foam tires. This tire size was the biggest available in a Lego set, in the early 1980s.
Alternative builds
The 8860 Lego Technic Auto Chassis also featured instructions to build a dragster from the same parts. It goes without saying that the build still featured fully-functioning engine block, transmission, and steering.
Image Credits: Technicopedia