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"Big Twin"
By Dave Brackett


     It was just before Christmas in 1970, Tom, Rose, Jim and myself were discussing the concept for creating a new three wheeler project for the upcoming Oakland Roadster Show. We decided on a three wheeler with some kind of body, and maybe four wheels across the back instead of two, and we would use two Sportster motors. I went to the drawing board and started sketching ideas. After  a day or so, I showed Tom my sketches and he approved. The race was on. I had drawn

big twin 4res

After bike repainted in purples several years later

up a five wheeler, with the two motors side by side, a three position seat, and the body had a roof over the riders. I also wanted to use an automatic transmission, as Tom wanted only hand controls.
     I finalized my plans and collected all the parts; two 1970 Sportster  motors, a C4 Ford automatic tranny, a stock Harley 45 rear end, round and rectangular steel tubing and four 18 inch wide automotive tires and custom wide automotive rims. The pressure was now on, I had only 32 days left till the Oakland Show.
     I started by mocking up the complete bike, placing motors, tranny, rear end, and wheels in their positions. First I constructed a main framework, from 1 x 2 rectangular tubing, to mount the motors, tranny and rear end. The tranny sat sideways, because I wanted to be true to bikes by using all chain drive.
     At this point, I was trying to create a body shape and design, and realized that there was not enough time to build molds and make a fiberglass body. The only choice was to fabricate a unibody type vehicle with frame and body all one, using steel for everything. First, I finished the drive train, a series of jack shafts and sprockets to transfer power to the automatic trans, then to the rearend. I custom built a torsion rear suspension, with two arms that ran between the two tires on each side of the rear, leaving the center space between the tires for the drive chain. Now

big twin 3res

The frame before I welded on the body panels

to create a body.

     Using round steel tubing, and following my drawings, I started to attach and bend tubes that would create the outer lines of the body.  They ran from the front neck back over the rear tires and up over the passengers heads to create the roof. About this time, the machine shop had finished the new springer front end.  I made it more narrow than those we sold, and used square tubing for the strength necessary for the extra weight of two motors. It was 20 inches over stock length. The bike was now on it's own wheels.
     To make the bike look symmetrical, we reversed the heads on the left side motor, and with some custom machine work, made the carb and exhaust go out the left side. The motors and other components went out for chrome and reassembly, and I returned to finish the body.
     I hand formed sheet metal panels for all the body areas and welded them in place. This took several days, and warpage was a continuing problem. Finally the finished motors were installed and after a quick test fire and test run, the bike was torn apart for paint. 

bigtwin chopper 1res

The bike when first finished in it's red colors with me

bigtwin chopper 2res

The bike when first finished with Jim Clark and me

     As usual, the paint was done by Molly, this time in reds with silver and gold trim. The bike was repainted later in purples. While this was being done, other parts were chromed and tires mounted, upholstery custom made by Whitey Morgan, and special parts machined by Henry's Machine Shop. I had to have the two outside rear wheels run on bearings, they were not driven, there was to much scuff trying to drive all four rear wheels. Henry also made adapters for chain drive to and from the C4 Ford Tranny.
     When everything returned, I reassembled the bike and the night before we left for the show, we fired the bike and drove it. The only problem was the brakes. They did not work well, but I later fixed that by adding a Hydrovac power brake booster, and since the two outside rear tires were just floaters, air pressure in them was reduced and increased on the two inside braking tires. While the bike was being cleaned and loaded into the trailer to go to Oakland, I quickly built a turntable to place the bike on at the show.
     Jim Clark and I left early the next morning for the Show, and the bike was a sensation. We won the Sweepstakes award, and the only problem was a broken weld on the rear torsion suspension. After returning home, that was repaired, the brakes fixed, and the bike was used as an advertising tool for AEE Choppers, for many years. 
     I have always been amazed in what I accomplished in 32 days.



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