Getting custom gears ground

 Hello fellow motorcycle tech people,

1) Supposing I am insane and want to fabricate my own motorcycle
gearbox for a shaft-driven diesel motorcycle project, where could I get
some custom gears ground?

2) In the quite likely event that having custom gears ground is
prohibitively expensive, and it turns out that I am still insane and
want to make my own gearbox, who makes stock gears for existing lines
of motorcycle transmissions that might send me a catalog with
specifications (or at least pictures of both sides of the gears,
dangit!) so that I can mix-and-match my own gear cluster out of
existing parts?

Any help would be greatly appreciated!

Chuck "No, really, I don't want to just use a BMW tranny" Perkins

 yes, custom gears are prohibitively expensive.
(yes, you are allowed to be insane and i have a bmw bike with a diesel
engine)
you may want to look at shaft to shaft  dimensions of existing trannys.
the gears can be used which are the correct shaft-to-shaft distances.
the old honda hawk had gears we would swap around to give different
intermediate ratios.
the shifting devices may be thought out for using different gears in other
places.
i'm interested in what you are trying to do.
the bmw tranny does need help. i don't like the ratios either.
sammmmm

 
SAMMMMM wrote:


What is the peak RPM your diesel engine turns? Is it "happy" with the
final drive gear ratio?


Is it a situation where low gear is just too damned low for the amount
of available low RPM torque? I would think you'd have to have a whole
new mainshaft made, as first pinion gear is usually a physical part of
the mainshaft...

 strangely enough, the low speed torque is real good.
the engine is governed at about 3600 which is good for about 63 MPH.
there's power for faster but the rear gears are the 2.91 (or such) and are
the highest offered
in the rears. there is a reductionnin all bmw gearboxes.
there are slightly higher tranny gears available from germany. they're
pricey.
my friend with a similar rig, tried them. they help but are not the final
answer.
i *could* run the governed rpms up but i hate to.
it's a yanmar 3tna72 engine.
sam

 
SAMMMMM wrote:

Yup. Diesel engines are known for their low rpm torque and ability to
pull heavy loads. I though you might have some larger diesel in there,
maybe a 1500 cc or so, but yours is only 879cc...


Diesel engines often run at 1800 or 3600 RPM so they can turn
generators. I looked up the yanmar 3tna72 engine. The Yanmar site
showed a snowblower that used it. 13.02 kw, 17.7 PS @ 2880 RPM, 879cc.
I reckon that it would have about 32 ft/lbs of torque, and if you
multiplied that times 2.91, you should have about 100 pounds of rear
wheel thrust, considering that most rear wheel diameters are close
enought to 1 foot in radius, it makes a foot pound of torque convert to
about a pound of thrust. That's enough thrust to go about 82 mph.

Vaguely related to diesel engines:

Several years ago, I was interested in a small company that wanted to
utilize hundreds of little 1500cc Yanmars to power generators and sell
electricity to the major utilities...

They had a mysterious proprietary technology they called "pulse
charging" and they were going to sell licenses to all the diesel
manufacturing companies to use their technology that improved the fuel
efficiency of diesel engines. They demonstrated the fuel economy of
their "pulse charged" Yanmar engine in an economy run at the California
Speedway, and again in an open highway test. The engine was mounted in
a Geo Metro sedan. It got around 100 mpg, if run continuously at 45
mph...

The company claimed that Asian manufacturers would be interested in
cars that got great economy at lower speeds than drivers on American
highways usually like to drive. Nobody wanted the technology though,
not even Yanmar...

I talked to the engineer that was developing "pulse charging"
technology. I looked into the engine when it was all torn down on the
work bench for modifications and the engineer dropped mysterious hints
that it utilized the same technology that had been used in the
German V-1 Buzz Bombs at the end of WW2...

Little did he know that I had studied up on pulse jets that used reed
valves and pulse jets that didn't use reed valves, and that I
understood the physics of such things as tuned headers...

It turned out in the end that their mysterious "pulse charging" was
nothing more than a tuned 3-into-1 header which wasn't patentable
technology....

They even showed potential stockholders a Yanmar with a 60 KVA aircraft
alternator bolted to it, and they claimed that was going to be the the
basis of a hybrid automobile they were developing. The
power would supposedly be trasmitted back and forth from the crankshaft
of the engine to the wheel of the car through the alternator's quill
shaft...

A quill shaft is about half an inch thick or less, it's like a torsion
bar. It allows an airplane engine to start an alternator turning when
there's already a heavy electrical load on it. If the quill shaft snaps
the alternator won't turn, but nothing major gets broken...

No way in hell would a quill shaft be thick enough to propel even the
smallest car. I told those guys that, first they got a little paranoid
that I was talking in front of potential investors, then they asked
what I did for a living. I said I was retired. They offered me a job.
They would have paid me in their worthless stock. That's how those
crooks paid their consultants and employees...