It's not often I stumble across a build that gets me truly excited! Even
more rare is getting to watch history in the making! I present to you
keyne's Before we get to the cooling system lets check out some of the other unique things he did on this build.  Many of you may recognize these as docs "ultimate torque arms." What he's done here is cut them up and then tapped them out to make them clamping. This way there is absolutely no play in the axle, and no annoying axle hardware. Then he welded them to plates.  This helped him mount the torque arms to the swing arm. To do this he screwed them in and then used the superest of super glue, dp420. Next up was the battery box. He made them out of fiberglass which he says, "Is like paper mache for grown ups. It's really not that hard to work with!"  Foam filler, and then silly putty and saran wrap to layer the fiberglass on.
Now for the fun stuff: oil cooling!  The first step was to have a custom motor cover made. It was made to except an extra large bearing. This gives it plenty of room for the cooling tubes and wiring harness.
Does it work? Of course! How well does it work though? Here is what he has to say: "I don't have any good data on motor heating/cooling yet - but the biggest thing for me compared to air cooling and stock motors isn't so much how slow it is to heat up, but rather how quickly it cools down. I was happy to just use my air cooled motor in spurts of power, but once it was hot I'd basically have to wait half an hour before I could get another decent run. Now not only is it hard to heat up, but if I travel fast for some time the cooling from the radiator really works well. Here's an example: playing around recently I basically did doughnuts in the sand for ages to heat the motor up - I think I got it to 90degC, then I rode up a gradual hill at about 60kph for a couple of minutes and by the top the windings were back to about 60degC - in real world riding at my current power levels (5-6kw) the motor just doesn't overheat. Since then I have added 50grams of thermal epoxy around the edges of the windings to imporve heat flow to the cooling channel (filling the air gaps with the thermal epoxy) but haven't had a chance to test it yet. So it's probably even better. I'd be surprised if using the same techniques I couldn't make a sub 5kg 9C motor that could handle the same continuous power levels - infact I'm pretty sure I could get away with a much smaller radiator if the thermal epoxy does it's job)" That's pretty darn cool to think about using a $100 commodity hub motor as a high power hub! But he wasn't done yet. He wanted to get rid of some unsprung weight.  So he took his grinding wheel to the motor and managed to remove about 1kg of weight. But he still wasn't done.  He had a carbon fiber motor covers made up. I'm utterly speech-less at how cool that is.  And here the rider is with his steed in a much nicer backyard than mine. An older video with his older 9c motor. He burnt it up pretty quick riding like this. Here is his build thread on the ES. He's not quite done so check up on it every now and then! In the future he says: "I hope to make liquid cooled motors available to people at an affordable price. My PhD work keeps getting the way  If you're interested, my future projects are based around that - a liquid cooled 9C and a custom carbon frame rather than everything just shoehorned into an existing DH frame."   |
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Bike of the week >
14 - Keyne's oil cooled dirt bike |
