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Old 02-27-2009, 06:22 PM   #26 (permalink)
Coyote X
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Join Date: Dec 2007
Location: Southen West Virginia
Posts: 654

Metro XFi - '93 Geo Metro XFi Convertible
90 day: 62.17 mpg (US)

DR650SE - '07 Suzuki DR650SE
90 day: 55.26 mpg (US)
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I ordered the motor directly from mars electric. That robot marketplace has insane shipping rates. I can always get that 48V controller later but from what I have seen everyone says go to a higher voltage to get more reasonable acceleration rates and top speed, plus it reduces the amps required. I am not really sure what controller to get though that is why I haven't actually ordered one yet. I always have the option of making my own but I really don't have the time to deal with it.

Just about all the AC controllers have regen braking so I will be able to use that no matter what. I have not seen anything over 48V other than the kelly controllers so I don't see a lot of options if I want to run 72V for now. I still have to get the motor mounted and a chain drive of some sort figured out so I have a few weeks at least to decide on the motor controller and voltage.

For the chain drive I have seen some specs on the motor saying it has an absolute max of 4000 rpm. So with my 175/70-14 tires I need a 3.9:1 ratio to allow the car to go 70mph without overspinning the motor. The best I can come up with is an 11 tooth 7/8 bore sprocket from that robot marketplace($18 shipping!!) and a 42 tooth from tractor supply for the axle. That is using a #40 chain so it is a bit smaller than I would like but it is about the only thing I can come up with that fits in the space. I can go to a max 3.75 inch diameter sprocket on the axle without hitting the lower control arm. That pretty much limits my options using a #50 or 525 chain since they would be a bit too big, so it looks like a #40 will have to do. Unless anyone knows a good place to order sprockets from that has a pretty good selection

The Metro axle shaft is 7/8 so it isn't going to be that hard to find a hub for it. The drivers side has lots of room for the motor and I could probably grind the flange on the control arm and get another quarter of an inch or so clearance if I need to go slightly bigger but it still won't let me go to something like a 38 tooth 525 without hitting. My only other option would be to put a 13-15 tooth gear on the axle and a gear reduction sprocket set somewhere to gear the motor down. That would be a lot more stuff that could go wrong long term since it would be 2 chains, 4 sprockets, and 2 extra bearings. I might have to do it though if the #40 chain won't hold up to long term use.

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