The Excelsior Project, 30: Upper Bevel Cover

Feb 24/07.  After returning from Davenport last year, the next four months were spent designing the bottom end and the bevel drive. I wouldn't have thought it would take that long, but it did. Around New Years, I decided to embark on another tight deadline: build a running OHC Excelsior for the Legend of the Motorcycle, May 5, California.  I knew the planets would all have to line up for this to happen. Shortly after, my sister read my horoscope, and told me the planets are all lining up! I will do my best, and put my trust in the universe.

So, I have about nine weeks left to make it all happen. I have half a frame built, all the parts to build wheels, two foundries are casting engine cases and frame parts this week (hopefully), and I have almost enough parts to build the forks. The bevel gears and shafts are being machined. I have rocker arms, pistons, and flywheels.  Rods are promised in three weeks, so now I know it takes five months to get custom rods from Carrillo (this time anyway).

After I get the cases they have to get  machined. Southern Cross is handling that, and also machining the bevel gear module and the aluminum/bronze oil pump. The head pattern is barely started, so a little concern there. I need a custom pinion shaft for the flywheel, and a couple of hardened spacers. Have to weld up the gas and oil tanks. Cam blanks need to be machined, and Ron Lacey tells me that because I have a long rod motor, and the pistons spend more time at TDC and BDC, that I need to look at his books that deal with cam timing specifically...  there's a lot of details with a project like this.

Here's a box of front hubs. Material is 303 stainless. Machined by Southern Cross in Surrey. I'll drill the spoke holes on the rotary table, in the mill, then polish them.

Rocker arms machined by Southern Cross from 4340 HT/SR. Nice! These are already 32 Rockwell, so no further heat treatment is required. They do need shot peening and nickel plating before the two needle roller bearings are pressed in.

And so, the upper bevel cover got re-designed for the fifth time. I really liked the fourth version, but there wasn't enough room inside for the gears. I figured out the new shape on Autocad, and machined six pieces of aluminum; holding them together with fast-setting epoxy glue. I scaled them up (1.015%) to allow for shrinkage, as this will be the pattern when it's finished.

The finished pattern ...  and I like the shape as much as #4. I filled in the aluminum gaps with bondo, primed, sanded, then spray painted. Now it's sent to Pacific Pattern for getting mounted on boards, and having a core box made to keep the inside hollow.

Flashback Fabrications 604-888-8785email
PO Box 401Lynden WA98264

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