Original Year	1999
# of pieces	1437
Categories	Cars and Trucks: Super Cars
Dimensions	61(L)x31(W)x20(H)
Features	Steering, V-8 engine, 5 speed synchronized transmission with reverse, suspension, differential, convertible roof, gull-wing doors
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8448 Super Street Sensation

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

With the 8448 Super Street Sensation, LEGO^® was clearly trying to advance the supercar to a whole new level, but not necessarily in terms of complexity. Whereas each previous supercar had built upon the previous, adding more and more accurate functionality, in this case the progress went a different direction. Functionally, 8448 lost 4-wheel steering and all-wheel drive as compared to 8880. It gained a couple more gears in the transmission, but the real novelty was the styling. The earliest supercars (such as 853) had no styling at all. Beginning at 8865 and continuing to 8880, there was an increasingly complex body built from Technic bricks. 8448 totally changed the paradigm by replacing all those Technic bricks with a highly stylized body. The body was now made from curved panels, ribbed hoses, and flexible axles. In nearly no cases were any of those parts straight. So rather than the "faceted" look of 8880, the look was now more "swoopy". Even so, the vast majority of the shape was only hinted at, with most of the external surface being empty space.

Even though the focus changed, that is not to say that this is not a functional model. It still has a V-8 engine, a rear differential, a 5-speed gearbox with reverse, 4-wheel independent suspension, working steering, and a damping system that can be used for either a convertible top or gull wing doors. Motorization could also be added with a supplemental set.

The company pulled out all the stops on the packaging as well. This is arguably the most complex packaging ever used in a Technic set. The large box had thick side walls and a top panel that flipped open. Inside was a plastic tray which organized 8 different smaller boxes and the wheels and tires. Each box contained a module such as front suspension or engine. Each module can be built separately and then combined together at the end.

The instructions are also without peer. The manual is truly massive at 316 pages divided into two volumes. The first volume contains the instructions for the chassis, and the second for the various body options. Not only does it contain full instructions for both the main model and a variant, but it also contains partial instructions for 4 other models: Concept Car, Racer, Hot Rod, and Buggy. Each of these subsequent models builds upon the main chassis and includes instructions for the functional components of the alternate model. The final aesthetic details are shown in a single picture but without instruction. However, at the time there was a program called BIT (building instruction tool) through which photographic instructions for these details could be downloaded. Sadly, this software has long since passed into obscurity so the only way to access these instructions is to find someone who saved a copy since 1999 (like me).

This model introduced a lot of new parts including curved panels, flexible axles, double bevel gears, steering hubs, dampers, wheels and tires. Apart from the wheels, tires, and hubs all of these parts would become standard in the future. Some of the red flexible and solid axles included in this set have become very rare.

Features
Complexity and Variability This is an incredibly versatile model. The instructions first show how to build the chassis which includes the gearbox, suspension, and steering. Everything is modular with the frame, the engine, the front suspension, the rear suspension, and the transmission all being separate modules. The engine can be mounted in either the front or the rear with no change to functionality. Then the instructions continue with body options. The convertible and gull-wing options are fully defined in the instructions, with partial instructions for four other possibilities. After that, a motor can be added to more fully realize the utility of the gearbox or, for the truly adventurous, a Mindstorms RCX can be added for remote control.
Steering The front wheels are steerable with a rack and pinion system. This is one of the very few not only to have the steering wheel usable, but to NOT have a "hand of god" control for easy play. Rack and pinion steering doesn't get much simpler than this. The steering wheel is connected to the pinion via a couple of universal joints. The rack is connected to tie rods going out to the steering knuckles. A second pinion is used just to hold down the long rack. Note that these steering knuckles do NOT include Ackerman correction. This is a bit surprising given the otherwise complex model and the fact that there is plenty of room inside the deep wheels.	Click for an animation of the steering in motion.
Engine This set features a front mounted V-8 engine. The engine is made from cylindrical engine elements and is driven by the rear wheels. The crankshaft is offset 1/2 stud from center, giving the pistons a stroke of 1 stud. The crank has 4 crank pins at 180 degree angles. Most V-8s have crossplane cranks with the pins at 90 degrees. While many racing V-8s do indeed have flatplane cranks like this LEGO version, they are always 0-180-180-0 instead of 0-180-0-180. The engine also has a number of aesthetic features such as an intake manifold and a 3 blade fan. The modular engine can be removed from the front and installed in the back instead, but only when the model is built in gull-wing mode. The whole process takes only a few seconds.	Click for an animation of the engine in motion.
Transmission The transmission is located between the seats. As a synchronized unit, this one does not need to be aligned to shift and can even be shifted while rotating. The photograph shows the shift lever and gate with the 6 positions. As the lever is moved through the H-shaped gate, one of the three driving rings is forced into position. Note that only one driving ring can be engaged at a time. Passing through the center of the H returns the opposite ring to center. The driving ring is the key to everything. It slides over the ridged axle joiner which we first saw in 1993. Small tabs on the driving ring allow it to lock along these ridges, but still slide with some extra force. The driving ring grips the longitudinal grooves on the axle joiner causing them to rotate together. A circumferential groove in the middle of the ring allows it to be pushed along the axle joiner in either direction. A set of 4 driving dogs on either end then mate with a 16 tooth idler gear allowing the idler's rotation to be either synched with the axle or allowed to spin freely. The animation shows how the driving rings work to engage and disengage the clutch/idler gears. The driving ring is shown in red. The lower axles are joined with the gray axle joiner. The driving ring rotates with the axles. At first, the driving ring is disengaged so both the dark gray and green gears are not driven and slip on the axle. The driving ring then engages the green gear and thus drives the blue gear. Because the driving ring does not use gear teeth but rather uses four tapered driving dogs, there is considerable backlash between the driving ring and the gear. The allows the driving ring to be engaged even while it and the mating idler gear are turning at different speeds. The computer images are coded to show the different gears paths for each of the 6 gears. The red parts go to the engine (front or back mounted). The yellow differential is the output to the wheels. You can see that the red axles interface with the other gears in two places: blue and green. This means that the red, blue, and green axles are always turning at different rates. Now let's trace each of the 4 gears starting always with the red engine axle: 1st Gear: (green ring, pink gear) 20:12 (green) x 16:16 (pink) x 16:16 (turquoise) x 20:20 (bevels) x 16:24 (final diff) = 1.11:1. 2nd Gear: (red ring, white gear) 16:16 (white) x 16:16 (orange) x 24:16 (yellow) x 20:20 (bevels) x 16:24 (final diff) = 1:1. 3rd Gear: (red ring, turquoise gear) 16:16 (turquoise) x 20:20 (bevels) x 16:24 (final diff) = 0.67:1. 4th Gear: (blue ring, orange gear) 12:20 (blue) x 16:16 (orange) x 24:16 (yellow) x 20:20 (bevels) x 16:24 (final diff) = 0.6:1. 5th Gear: (blue ring, tan gear) 12:20 (blue) x 16:16 (tan) x 16:16 (turquoise) x 20:20 (bevels) x 16:24 (final diff) = 0.4:1. Reverse: (green ring, dark gray gear) 20:12 (green) x 24:16 (dark gray) x 20:20 (bevels) x 16:16 (final diff) = -2.5:1.	Click for an animation of the transmission shifting.
Suspension All 4 wheels have independent suspension. Front suspension is a standard double wishbone type. The unique steering knuckle with upper and lower ball joints as well as the tie rod joint is used. It was never used again. Because it is a four bar linkage, the wheel stays perpendicular to the ground throughout its travel. A pair of shock absorbers provide support. The rear suspension is also a double wishbone type, but because it is unsteered ball joints are not needed so standard liftarms are used instead of control arms. The suspension on this model is quite soft compared to other supercars. The front suspension depresses about half way under the weight of the model, which is exactly as it should be. This means the shocks can both extend or compress from neutral.	Click for an animation of the front suspension in motion.
Differential This set uses a differential gear on the rear axle. It incorporates a built in 16 and 24 tooth ring gear, either of which work as a spur. In this case the larger 24 tooth is used. 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.	Click for an animation of a differential in motion.
Convertible Top The convertible top uses a clever mechanism which is powered by one of the new dampers. The gray ball joint shown in the computer image is the trigger. Pushing this down lift the pair of black steering arms, thereby lifting the 6x4 bent liftarms. This drives the cams attached to the damper over center. Once this point is crossed, the spring slowly lifts the roof into position. The roof mechanism itself is a 4-bar linkage which keeps it parallel to the ground. Both the up and down locked positions line up perfectly with the car. I prefer the car in convertible mode because in gull-wing mode the back looks too empty. Additionally, I prefer the top down.	Click for an animation of the top opening.
Gull Wing Doors The convertible top mechanism can be removed and converted to a pair of gull-wing doors. In this mode, a ball joint on each side is used as a trigger. Pushing the ball down turns a vertical crank (shown in gray). The crank pushes the axle (shown in red) into the damper, forcing it over center. At this point, the spring slowly lifts the door. This mode uses many more parts than the convertible mode, nearly all the parts in the set. In the convertible mode there are a lot of spare parts. There are not enough parts to build modules for both modes at the same time.	Click for an animation of the doors opening.
Motorization The model includes a set of yellow jack stands which can be used to lift the rear wheels off the ground. When used in combination with a motor (available as a supplemental set), this allows the user watch the engine turn at a constant while the rear wheels change speed as you run through the gears. When the model is in gull-wing mode, the space in the rear is just the right size for a Mindstorms RCX. Three motors can be added: two for drive and one for steering. With the addition of an RCX remote, this was the very first wireless, remote controlled Technic model.
Wheels and Tires Both the wheels and tires are unique to this model. The wheels are metallic silver and have a large offset with a lot open space inside the dish. This allows the steering axis to be near the center of the wheel. This is the only Technic model with such geometry. The pattern on the wheels is directional, so it looks like it is rotating the wrong direction on one side of the car. The tires are 81.6x34 ZR with a unique tread pattern. They are the same diameter and width and the tires of 8880 but lower profile.

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Front View	Back View
Top View	Side View
Computer Render	Computer Render

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8448 Super Street Sensation

Features

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