After first discovering that my car would not go, and smelling a
nausiating burning fiberglass smell, not to mention the sound not
unlike bacon sizzling, I discovered my motor was sick. Upon further
inspection, I came to the conclusion it was fried, and it looked like
my citicar was gonna be a big paperweight. Well, I removed the motor
and dissasembled it and found burnt brushes,a broken brushholder, and
a charred, nasty looking commutator. It looked bad, so I brought it to
the local DC motor shop to see if they could help me......after 3
weeks they said they could help me but it would cost a ton of money,
so I took back the motor and went to searching high and low and in
between for a new or better motor than what I have. This is what I
found out. GE has the drawings for that motor but essentially nothing
else (a few generic type parts is all they have)and nowhere, and I
mean nowhere is there another motor that has 16 splines on the shaft.
With this in mind, we inspected the motor again and with the help of
an electical engineer friend of ours(we call him Mr Wizard) , we took
to measuring the windings in search of a short. We lucked out.....no
shorts in the windings but what we did find was a ton of bad
connectons where the copper wires connect to the commutator. The
connections that were discovered to be bad were caused apparently by
the mechanical connection being loose with copper oxide in between.
Now, we figured tig welding would fix the connections, but could not
find a welder we were comfortable with and also afraid that the heat
would melt the mica insulators in between the commutators. After
turning the armature down and resurfacing it on the lathe, we undercut
the mica to .032 and decided the best method to reestablish a good
connection was by mechanical means. O.k. now for the part you have all
been waiting for.....how we did it. First we set the armature up on
the mill standing with the comutators upwards. Then with a special
constructed drill holder and a .062 drill we carefully drilled into
the commutator/wire junction to a depth of .125 being careful to not
get too close to the insulator (one slip too close and a short occurs
and it is all over buddy), after the hole was drilled, without moving
position on the mill we inserted a special holder that held a "pin"
that was essentially a 1/2 inch long, 16 guage piece of houshold
wire secured in its holder by a set screw. Next step, coat the wire
"pin" with a thin coat of Muratic acid to clean any oxide as it goes
in, then with the mill on high and being sure that the pin is straight
quickly insert the pin till it friction welds and snaps off. If done
perfectly, you will have a flush joint but some times they break off
either high or a bit low but they are still o.k.You can cut the high
ones with some flush cutting cutters. After doing this in all 37
commutators and placing 4 pins in each (2 pins per wire), we load
tested the armature by placing 10 amps at 12 volts across each
winding, and measured each connection and found all connections were
back to approx the 7 mv drop that we expected to find with this setup.
After re-assembly with a new brushholder and brushes, we reseated the
brushes for a perfect fit. Next step was to bench test the unit, we
strapped it down on a workmate and applied 12 volts to the motor....IT
WORKED...purred like a kitten, now time to reinstall it in the former
paperweight, now to be hopefully known as my C-car again (not those
god awful names I was calling it 3 weeks earlier). Installation was
much easier the third time around and now I get to drive......what did
I experience? Well, the jerky motion was gone.....the smell was pretty
much (just a bit lingering from the prior smoke filled incident), and
instead of 0-10 in 3 hours, it goes like 0-30 in a few seconds ALMOST
like a rocket ship. So, with the increased power and the natural
design of the car it really is like an E-Ticket ride at Disneyland
when you are going at high speeds. In conclusion, the experience was
long, tough, tedious, and not always fun, but it did work and I have
my car back. If you would like any additional information on the
things I found out or repair techniches, please feel free to email me.
Thanks for listening.
Also, I would like to thank all group members who contributed
information, thoughts and/or insights about my motor problem, it is
very much appreciated.
Anthony
