It’s been way to long since my last entry so I thought I’d better sit down and get to it.  Being KillaCycle will be racing again at the end of this month Bill Dube thought it might be a good idea to have me go through his oldest, most battle weary motor which is now his spare.  Although I did some earlier commutator end plate work for Bill and got him a new spare motor this was my first look at what damages were occuring from repeated high speed runs Bill was putting them through with those new A123 batteries.

Before I begin I thought I’d add that KillaCycle is also featured in the April issue of Hot Rod.  The article talks about the You Tube video which “ends with motor destruction”.   I bring this up because although the motor did get a bit hurt “all and all” it wasn’t that hurt and no where near what I’d call destroyed.  Most of the damage is located in the brush rigging.   Although there was conciderable burning of the Nomex field coil insulation from the resulting arcing we saw, the fields and armature cleaned up remarkably well as you’ll see.  This was intresting to see being the arc shows it’s able to burn 10 mil Nomex arimid paper from a few inches away.  The heat this arc causes is so hot that it just vaporized a steel brush ring mounting screw head from about an 1 1 /2″ away.  Being the armature and the fields are the expensive parts and seeing that the arc had been able to burn the nomex almost to the pole shoe hole it confirmed my attitude about added insulation for those pushing these motors.  I triple ply wrapped the fields with .007 thick fiberglass wrap and double dipped them.  I then lined them with 10 mil Nomex where they meet against any steel part of the housing for a double layer of insulation.

Now this motor has had some history on it and somewhere along the way it’s CE plate (brush end) broke one of it’s radial lips.  This allowed the plate to drift off center and the armature rubbed against the pole shoes.  Luckily it didn’t rub hard and there was no lasting damage, this may have in fact added friction and load enough to have helped set off the fireworks we all saw, face it, it sure didn’t help, lol.  The second thing I noticed was the only resulting damage to the armature was the rounded corners of the comm bars along the mica slot edge.  I’ve never actually seen it arc while it’s happening but the damage tells me that what we see as a single spark is an electric machinegun of arcing as each bar passes the holder it’s arcing to which removes a tiny little bit of copper from each bar.  Luckily the brushes do not ride that close to the edge so it has no impact on future commutation.  After turning the commutator I hand X-acto’d each slot to even out the slots and to create as crisp a slot as I could.  In the end I doubt any could tell this re-worked armature from a new one 8^)  While I had it I dressed up the inhouse shaft shortening “someone did”, and drilled and tapped out a center hole so Bill could use this motor with or with a speed sensor being it’s his spare.

Addressing the arc issue I came up with some Nomex shields to help protect the thin and fragile springs.  Like I told Bill, so what if it arcs to the main brush holder body (not great but) if we can keep the springs intact and not loose brush tension he could get an extra run or two in, and get those back to back runs for his record setting goals.  Anyway I hope you enjoy the pics, they really show what can be done with an old beat up battle scared motor.  I’d like to thank Bill Dube and all of the KillaCycle team members for allowing me the honor of being able to work on thier motors.  In the end it’s working with the racers that I can learn where damages occur and what can be done to prevent it.

Hope you all enjoy, here’s a link to the PICS

The armature cleaned up like a new penny 8^)