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Old 01-03-2012, 08:30 AM   #74 (permalink)
Arragonis
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Quote:
Originally Posted by Frank Lee View Post
It's easier to teardrop a body with one wheel on one end.

Maybe tires are not as sensitive to scrub as I imagine, but one wheel should not suffer side scrub by itself from imperfect alignment/track changes through suspension travel.

One spring/damper assy ought to be lighter than two.

Trikes aren't mainstream because they are more load sensitive. The lowest common denominator users out there can't be trusted with that. Add wheel #4, gain lots of safety margin.
Teardrop -
The Citroen Coccinelle managed a neat teardrop (the original name was "A Drop of Water") with 4 wheels. It had stability problems though due to weight distribution (in this case due to the passengers and engine being too close to the front).



We've also seen some pretty neat teardrops here on EM - the Dolphin for example.

Geometry -
How do you keep the rear wheel upright to the road with body lean ? When the body leans it would ride on the edge of the tire instead of the face ? A wheel at each corner can have suspension geometry keeping it flat.

The VW Scooter had this issue



This could be more of an issue if you plan on using RWD (maybe motorbike as Mech may be planning ?) then you need a tyre wide enough to cope with the extra weight over a bike, and also giving reasonable traction in the wet. A peaky MC engine, singe rear wheel and a hill start in the rain will be fun

Weight -
Lomax made 3 and 4 wheelers (both FWD based on the Citroen 2CV) in the 1980s





I don't think the difference in weight was that much - just one suspension arm and lever to connect it to the central spring in between the suspension units - and the 4 wheeler has the advantage of having some luggage space between the rear wheels.

As you tap though anything this light is going to have issues when loaded. I would suggest that extra wheel (and weight required) would minimise that but I'm sure someone has a neater solution to make it work.

And yes, none of these went through crash testing as they were sold as kit cars.
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