Technic
Set 4404

This set is new for 2003. It includes intructions for several models of cars, trucks and motorbikes. The main model is a pickup truck. It is made up of two main parts: a chassis and a body, just like a real truck. The pictures below show how I built my set: the body is more or less per instructions, but the chassis is all new. The original has no steering and has 4 wheel independant suspensions.

A few overal views:

Under the hood is a V8 engine. In order to fit it, I had to completely rebuild the structure of the body.

The main addition up front (appart from the engine) is functional steering. This was quite a challenge because I wanted the steering to be actuated from the steering wheel in the cab and still retain as much as possible of the scale and detailled interior of the original model.

Here is the front suspension and steering shown with one wheel removed for clarity. Notice the sharp angle of the double universal joint used to link the steering wheel to the steering mechanism. Because of the way the rack is mounted I had to use a 16 tooth gear to drive it, to compensate for that "quick acting" setup, I added a 1:3 gear reduction between the sterring wheel and the shaft driving the rack.

The truck uses a solid, live axle setup at the rear. It has coil springs with a Watt linkage to reduce side to side motion (see this prototype. I used an old style differencial because it is more realistic than the new one and in this model there is no need for high torque to be transmitted.

After I took these pictures I noticed a couple of problems: the rear wheels are two studs narrower than the front ones and sometimes the rear tires can rub against part of the suspension. I have now changed the cross axles holding the wheels from 8 to 10 stud long fixing both problems.

One remaining issue is the fact that the front suspensions are far more stiffer than the rear one... I'll try swapping the springs or moving the moutning points a bit to see if I can get a good match.