Saturday, May 9, 2009

The "Mo-Bubble"

This is the story behind my 1992 Microbubble, or "Mo-Bubble" as my friends call it, a home-built I concocted this past summer.

The Microbubble came about because of my interest in the English Peel Trident, a true bubble top car that is very rare today. Only a few dozen were built back in the Sixties, and even trying to find photos of one could keep you busy for years.

Not being able to find a Trident, or even get much information on one, I decided to build one myself (or at least something similar in size and shape).

I started with a discarded Isetta frame. I first narrowed it 9 inches and shortened it 22 inches. For power, I decided to use a 50cc Honda Express moped engine/transmission. I welded a moped steering knuckle to the axle, then added handlebars and a seat. I ended up with a very stable 3 wheeler that was fast and fun to play with. This lightweight chassis was very stable, even at its full speed of 30 mph, or during hard cornering.

Next came the body. Much through went into its design, construction, and the selection of materials. I sketched every aspect of the construction phase. When an idea came to me -- no matter when or where -- I wrote it down: on envelopes, pads and even my shirtsleeves. From these initial scribbles came the drawings I later used.

For the body framework, I decided on EMT conduit. Using a maple tree as a jig, I bent the tubing to shape and welded it together.

The body panels are 3/16 UHMW Plastic-delrin sheets that I bought cheap at a sale. I pop-riveted the plastic to the frame, clamping as I went along. I found out that practically nothing will stick to the body panels -- adhesives, glues -- even paint! I had to rough up the surface with a D/A and 180 paper to finally get a coat of paint on it. Urethane foam panels were shaped and glued with paneling adhesive to the interior of the body panels. This added stability and soundproofing. I covered the foam with grey felt carpeting to finish off the interior.

The entire body tilts forward like the original Trident for exit and entry. The body is held up by a gas strut when open. The starter is a lever on the left that is pumped forward and winds a spring that is released by the brake lever and starts the engine. Steering is by handlebars and the turning circle is 10 feet or so. There's only one brake -- a drum on the rear wheel -- but it stops well. The engine is adequate for the average person in weight, but the car is not much of a hill climber. Top speed is 30 mph and the unladen weight is 210 lbs. The car's length is 66 inches. (This makes it the second smallest car in the world.) Body width is 42 inches and height is 50 inches. It uses 12-volt lights all around with no battery necessary.

Driving the Mo-Bubble is a blast! Its light weight, tiny size (much smaller than an Isetta!) and easy maneuverability make it a quick, fun microcar. Just ask anyone who saw it at the Canfield Ohio Show this summer or the National Meet this fall.

I currently have this micro licensed and insured in New York State as a moped, class B, which covers vehicles with speeds up to 30 mph.

If you didn't get a chance to see the Mo-Bubble during the 1992 season, look for it at meets this year!


By Steve George, Marathon, NY
From the back issues of MINUTIA (Volume 2, Number 1, Winter 1993)

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