Thursday, December 17, 2015

Diesel Land Speed Racer Mk2 - Part 9 - Installing The Main Drivetrain Bearing

The main drivetrain bearing is mounted to the central frame casting on a pair of machined aluminum blocks. This bearing had to be perfectly aligned to ensure that the secondary shaft was perfectly parallel to the engine's crankshaft. Additionally, the bearing must be strong enough to support the full force of the engine's power while transmitting to the rear wheel. 

I made the bearing blocks out of 6061 aircraft aluminum and assembled the parts using automotive suspension-grade flanged bolts and nuts.

Sunday, December 13, 2015

Diesel Land Speed Racer Mk2 - Part 8 - Machining the Transmission Mounting Plate

The transmission mounting plate is one of the most important pieces of the entire motorcycle, and took 3 weeks of planning to properly fabricate. I do not have access to CNC machinery or a large mill at the moment, so it was necessary to manually carve the plate using a band saw, a drill press, assorted hand files, and a block sander.

The plate must perform several functions. Most importantly, it serves as the mounting surface for one of the countershaft bearings. For the CVT transmission to work correctly, the center-to-center distance of the two shafts must be set to a precise dimension (in this case 9-3/4 inches). Therefore, the placement of the bearing block on the plate, as well as the plate's mounting location on the engine block, is crucial.

Additionally, the plate acts as a major structural component. On one end, it is tightly bolted to the engine block. On the other, it is fastened to a large threaded rod that is mounted in the central frame casting. This is extremely important,  because it allows the force from the engine to be transferred through the heavy aluminum plate, rather than through the frame tubes. It also improves the rigidity of the whole chassis.

Step 1 - Layout the overall dimensions on the material.

My "Manual CNC Machine"

Step 2 - Begin carving outer shape, and drill layout holes. Use 1 inch holes for the shafts so that the plate will accurately locate on the crankshaft

Step 3 - Locate the plate on the crankshaft, and determine the position of the hole for the large threaded rod.

Step 4 - Drill hole for threaded rod, and finish carving the rough shape.

Step 5 - Prepare threaded transfer punch.

Step 6 - Install the threaded transfer punch in each engine-block bolt hole to be used, and hit plate with a hammer to punch the locations for the bolt holes to the plate.

Step 7 - Mark out the locations of the mounting holes

Step 8 - Drill and test-fit the mounting holes.

Step 9 - Enlarge the shaft holes once the layout process is complete.

Final installation :-D

Monday, November 30, 2015

Diesel Land Speed Racer Mk2 - Part 7 - Fabricating The Seat

Between fabricating major components, I quickly made a simple seat for the Sportster diesel. I used a piece of flat steel plate, cut it out to match the frame rails, bend the end to match the fender, and had it powder-coated flat black. The front has a notch that slots against the original seat bracket, and the back is held in place by a button-head bolt.


Sunday, October 4, 2015

Diesel Land Speed Racer Mk2 - Part 6 - Starting and Stopping

The engine in the Diesel Sportster is 3 times larger than the engine in my first bike, so it requires an electric starter and a fuel pump to operate correctly. It also has a heavy-duty solenoid that holds the governor open, and snaps closed to shut the engine down when the kill switch is used. These are all relatively high-amperage systems, so a single fuse and normal switches were not enough to safely control them. 

For the electrical system, I used a marine-grade 6-fuse block and a pair of automotive relays. The fuses protect every individual circuit which will simplify troubleshooting, and by using relays I can avoid sending high amps through the relatively fragile handlebar switches. All of the wires are color-coded, with yellow wires for the starter system, white wires for the governor solenoid, red for main power, black for control switch power, and green for ground.

The fuel pump is another marine-grade unit which is rated for most types of fuel, including biodiesel.

Now that starting was done, it was time to focus on stopping. The original Harley calipers suffered an extreme design flaw. The bolts that held them to the swingarm screwed into nuts that were captured in hexagon-shaped holes in the alloy caliper body. Unfortunately, when these need to be removed and rebuilt, the bolts have inevitably seized from rust and the nuts tear open the hexagonal holes, wrecking the casting and making it impossible to tighten the bolts correctly during reassembly.

The caliper I purchased (for cheap) of course had been discarded because of this damage. I drilled out the old shoulder bolts, milled the hexagon holes round, installed steel spacers to keep the new nuts from gouging into the alloy caliper body, and installed modified 7/16 diameter socket-cap bolts and locking nuts.

NOS replacement bolts, which were unusable because the chrome was flaking off.

Final installation.