Original Year	1990
# of pieces	220
Categories	Cars & Trucks: Buggies
Dimensions	26(L)x15(W)x15(H)
Features	Steering, rear suspension, 2 cylinder engine
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8840 Rally Shock 'n' Roll Racer

Click the image to download the LDraw file of this model.
Model by Benjamin Wendl

This is one of 3 1990 models centered around a "Rally" theme. This model is a dune buggy with working swing arm rear suspension. A V-2 engine is located between the rear wheels made from the new engine parts introduced this year. The front wheels have rack and pinion steering. The Technic figure also made a reappearance here after being absent for a year. Toothed elements were used to make a roll bar.

Each of the Rally vehicles had a special numbered flag which matched the third digit of the set number, in this case "4". This is the first set to include an engine made of the new engine parts, and one of only a few models to date with suspension other than the big super cars. In my opinion, this is one of the better looking small buggies.

Features
Steering The front wheels can be steered using a wheel at the driver's position driving a 16 tooth spur gear. This spur gear mates with a rack at an angle and drives the steering arm back and forth. The steering mechanism itself uses control arms and toothed links as shown in the computer image.	Click for an animation of the steering in motion.
Engine The V-2 engine is located between the rear wheels on the swing arm assembly. Because of the location, the engine changes angle as the suspension goes up and down. This can be seen in the animation. The engine is made from the new cylindrical engine elements and is driven by the right hand rear wheel. The wheel axle connects to a pair of 14 tooth bevel gears. The second stage is a set of 8 and 24 tooth spurs, resulting in a gear ratio of 3:1. This makes the engine turn quite quickly when the model is pushed. The final axle drives the crankshaft of the engine. The crankshaft is offset 1/2 stud from center, giving the pistons a stroke of 1 stud.	Click for an animation of the engine in motion.
Suspension The rear suspension is a swing arm variety which has a live rear axle (not independent). A pair of spring shock absorbers support the axle and engine. The shocks are installed at an angle almost parallel to the swing arm giving them poor mechanical advantage. This effectively increases the spring rate, making the suspension stiffer.	Click for an animation of the suspension in motion.
Wheels and Tires This set has 4 of the new 20x30 solid foam tires mounted to the older wheels. This is the first set to use these tires.

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Side View	Top View
Front View	Back View
Computer Render

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8840 Rally Shock 'n' Roll Racer

Features

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