Now on to figuring out the drive arrangement. Above is the
glider pretty well stripped down and the electric motor set in to see
where it might fit. I had hoped to put the motor behind the seat
post, but it just wouldn't fit so it will have to go in the
"normal" engine cavity. The problem is that the motor
needs to stick out quite a ways on the right side to get the sprockets
for the primary drive aligned.
For now I am planning to put the motor in front of the
seat post, but up high where it will be under my leg in a riding
position and also will leave the foot board clear. There will
probably be a little interference with the transmission shifter and I
will have to deal with that after the motor is installed.
Above is a test mount being made out of medium density fiberboard (MDF)
to make sure the dimensions are right for the motor mount and below is
the pattern being tried on the motor and the frame.
This allowed me to check the clearance for the drive chain as well
and I found I needed to shorten the top mount a little to make the
clearance.
Here is the motor mount as finished in aluminum on the left and on
the right is the motor mounted with the drive chain attached. For
now I have used a taper lock bushing with a single key in one of the
splines on the motor shaft. If this doesn't hold the torque, then
I may have to create a splined bushing with a series of keyway
broaches.
And a close up view of the motor sprocket mount.
I have been able to jack up the rear end and spin the wheels with a
12 volt battery and now the next step will be to address the brake
problems. I can't even drive it across the drive way without a way
to stop it!
I changed the drive sprocket to 20 tooth after the first
test drive since I was afraid of the current draws I was seeing.
Below is a picture of the smaller drive arrangement, but I have since
changed the drive back to the 40 tooth shown above.
June
06;
I have now changed the drive system to get rid of the transmission
and mount the motor behind the seat post. This will leave the
"motor bay" empty and I will either use the space for a
battery charger or maybe a hamster wheel for fun.
The
primary drive is a toothed belt with a 3:1 ratio to a jack shaft and the
rear drive is still a #50 chain with a 2.64:1 giving me an overall ratio
of 7.93:1. This may still be too high and I may take the rear
ratio up a little as I think I can get another tooth or two off of the
driving sprocket.
The jack shaft is mounted through a block of
aluminum with flange bearings on either side. The top is drilled
and tapped to hold a base plate for the motor mount and the bottom is
drilled and tapped for the existing transmission mounting
arrangement. The motor mount is bolted to the edge of the base
plate and is slotted for belt tension.
Above
are views of the jack shaft mount and motor base plate from both sides
of the bike.
This is the first iteration of the motor mounting plate, I had to
go back and make the adjustment slots longer and also slotted the three
holes along the one flat side. I can not imagine trying to make
this type of mount without the CNC mill.
Since I removed the
transmission, I lost the reverse gear so I am adding a reversing
contactor set. I have put the information on that modification on
the wiring page.
After the first 40 miles or so, I determined
that I needed a fan on the motor for extra cooling. I used a small
12 volt heater fan from the wrecking yard and built a shroud and
ductwork to direct it into the brush end of the motor as shown in the
pictures below.
The blower inlet is on the bottom and it blows into the back side of the
triangular plenum in the right picture.
At some of the show and tells
I have had people mention their concerns about the open drive system so
while waiting on the body and paint I made a belt guard for the primary
drive.
I used stainless steel for the guard as I find it easier to weld than
aluminum and it polishes up nice.
After the body and fenders came
back, the motor started looking pretty bad so it got a paint job as
well. It was a good thing since I found a bit of wear on the
inside of the end bell where the new bearing was rubbing. A few
minutes on the lathe took care of the clearance problem. I can't
say for sure, but I expect it also helped my range by removing
that little bit of drag. I know it will allow the motor to work
much longer. The end bell also got a quick polish job too while it
was apart. It will tarnish since it is aluminum, but it
looks good right now.