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Original Year
1988
# of pieces
892
Categories
Cars and Trucks:  Super Cars
Dimensions
60(L)x32(W)x21(H)
Features
Steering, 4 cylinder engine,
3 speed transmission, adjustable seats,
4 wheel suspension, differential,
retractable headlights
Other Views

8865 Test Car

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


Set 8865, released in 1988, was the third generation auto chassis and improved upon the technology in the previous version, set 8860, in many ways.  It features a 4 cylinder reciprocating engine in a V configuration, a 3 speed transmission, a working rear differential, working front and rear double wishbone suspension, rack and pinion steering, retractable headlights, and adjustable and reclining seats. 

This set introduced many firsts for Technic.   This is the first Technic auto chassis to feature a body.  The body, while crude, still gives the model shape.  It also offers a wealth of parts.  At almost 900 pieces, this was the largest set to date and has 24 16L beams.  This is the first set with true double wishbone suspension, and the first set to offer suspension of any type on the steered axle.  Several new parts are used on the front to accomplish the new suspension.  This would be the last set to include the square pistons, which would soon be replaced.

This model is about the same physical size as the previous two auto chassis which remain, to this day, among the largest of all Technic models.

Features

Steering
The front wheels can be steered using a new wheel at the driver's position.  The wheel axle passes through a pair of universal joints, then through a triplet of 16 tooth spur gears.  Finally, a pinion drives a rack.  The rack uses the new ball joints at each end to attach to new tie rods.  The tie rods connect to the new steering arms with more ball joints.  The steering arm itself pivots on upper and lower king pins which fit into sockets in the control arms.

In this Technic set, the steering employs the Ackerman Principle based on the shape of the new steering arms.  You can see in the images that the tie rod attachments are not directly behind the kingpins, but are inboard.  The result of this is that the wheel on the inside of the turn is rotated more sharply than the wheel on the outside, which is exactly what is required for a turning in a proper circle without skidding.
steering    steering2
Click for an animation of the steering in motion.
Engine and Transmission
This set features a rear mounted V-4 engine.  This is the first set to feature an engine in a V configuration other than the special engines set (858).

The engine uses the offset axle holes of the 24 tooth gears to make a crankshaft.  Connectors placed end to end and clocked 90 degrees form rods which connect to 4 specialized 2x2 square pistons.  The "cylinders" are actually square.  Each pair of opposing cylinders shares a common crank pin.

The engine also has a number of aesthetic features such as a pair of exhaust manifolds.

Ahead of the engine is a 3 speed gearbox / transmission. The color coded computer image shows the configuration in each gear.  The version on the right is in neutral.  The middle axle translates forward and back which allows different gears to mesh.  The upper axle with the 1/2 bushing goes to the engine.  The differential drives the wheels.

In 3rd gear (green), the path to the wheels is (16/16) x (16/24) x (28/14) = 1.33:1.  In 2nd gear (blue), the path to the wheels is (16/16) x (24/16) x (28/14) = 3:1.  In 1st gear (red), the path to the wheels is (24/8) x (16/24) x (28/14) = 4:1.

The gearbox is not synchronized in any way, so it is difficult to shift gears since they tend not to be aligned.


engine    xmsn
xmsn    xmsn
Click for an animation of the engine in motion.
Click for an animation of the transmission shifting.
Suspension
This is the first LEGO® set with suspension on all 4 wheels, and the first to have suspension on a steerable axle.  All four wheels have independent suspension.

The front suspension uses the new control arms parts (blue) and steering arms (white).  Upper and lower ball joints form king pins, making this a double wishbone suspension.  Because it is a four bar linkage, the wheel stays perpendicular to the ground throughout its travel.  A pair of shock absorbers provide support.  An extra vertical 6L beam helps support the four bar linkage so that not too much vertical stress is put on the steering arm.

The rear suspension could have also used the new control arms, but instead forms the control arms out of four beams.  An assembly of plates and beams forms the hub which pivots on longitudinal axles.  A pair of vertical two blade rotor parts are used to support the four bar linkage.  Power is driven through a pair of universal joints on each side.  The pivot point of the u-joints is carefully aligned with the pivot points of the suspension.



suspension    suspension

suspension    suspension
Click for an animation of the front suspension in motion.
Click for an animation of the rear suspension in motion.
Differential
This set uses a rear diferential gear.  It incorporates a built in 28 tooth ring gear which can work either as a bevel or a spur, similar to the 24 tooth crown gear.  It is made to house 3 of the 14 tooth bevel gears.  One is on each axle, and one planet gear in the middle allows the axles to turn at different rates.  This addition results in very smooth turns for this model.
diff    diff
Click for an animation of the differential in motion.
Seats
The seats are adjustable in both position and recline angle.  A pair of longitudinal axles support each seat and allow it to translate forward and back.  A rack gear runs parallel to the axles.  A pinion gear attached to the seat can be turned via a crank, driving the seat forward (see computer image and animation).

In addition to the ability to adjust the position of the seats, these seats also can be reclined!  Recline is based on simple finger hinges which tend to not be tight enough to support the weight of the seat back if the angle is more than a few degrees.

There are no rear seats.
seats     seats
Click for an animation of the seats in motion.
Headlights
This is not only the first auto chassis with a body, but the front end features retractable headlights.  A lever in the cabin pushes an axle forward and back (see computer image).  This axle turns a crank which pushes up the headlights about 45 degrees.
Wheels    lights
Click for an animation of the headlights opening.
Wheels and Tires
This set uses four foam 24x43 tires and wheels, the biggest foam tire that LEGO® made.  This is the only set to ever have these wheels in white.
Wheels
 


Other Views

Side View
side view
Top View
top view
Back View
back view
Bottom View
bottom view
Computer Render
render
Computer Render
render

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