4.5KW hub motor mounting problem - Axle keyed differently
I received my XM-3500li back in the beginning of December 2009. I rode it for a week before disassembling it to modify it with an extra 4 lithium cells, a BMS, a 4.5KW motor and a controller with regen.
It got to be too cold during the winter to really work on it, but now that things are warming up I'm excited to finish this conversion.
Yesterday I removed the rear hub motor wheel and took it down to the local motorcycle shop with my new 4.5kw Kelly hub motor to have them swap the tire and disk brake. Today I tried to mount the new motor on the moped, but I came across an unexpected problem: The original motor's axle has cut-outs on both sides to hold it securely into the frame. The new Kelly motor only has the cut-out on the side where the electrical cables come out, but not on the side with the disk brake.
I've attached pictures of the problem. So what do I do? I have an angle grinder that I could use to cut down the axle, but I'm afraid I might damage the thing.
I've heard of others creating XM-4500's, so how'd you make it work?
Mark the area with a felt pen first and then carefully scribe as you have hi-lighted in the photo. Put the nut, or nuts on the shaft and lock them together to protect the treads if you slip with the grinder. Use the angle grinder to carefully remove the bulk of the material. Leave @ 1/8" and use a file to get the exact profile you need. Get a cheap caliper from Harbor Freight to check your measurements as you go.
The alternative is to use a die grinder on the swingarm. How is the 4.5Kw axle stopped from rotating in comparison to the 3.5Kw? With more torque, you must be sure the axle can not rotate and destroy the wires going into the motor.
I have sent you a PM
I've always found that on precision machining on a valuable part someone who really knows what they are doing is worth the money. I'd say find a good machine shop.
IF you do modify the axle, be sure that you get it accurately lined up with the other end! -- Also, be sure that the frame/axel slot on the vehicle is heavy enough to retain the axle without rotation, as this more powerful motor will put much more stress on its mounting. is there any additional bracing, or torque bracket supplied?--If not, use of a quality machine shop would probably be your safest and best bet, for any alterations.-Good luck!-Bob
I've heard of others creating XM-4500's, so how'd you make it work?
I don't remember encountering this problem. It's possible that the motor axel configurations changed in the interim. It's been a long time since we did our "XM-4500" - I'll check it out at the workshop (likely not until Wednesday though).
The "smooth part" on the 4500 appears to be a sleeve. Do not bend the frame. I agree with the advice of taking both motors to a machine shop.
Maybe try a sympathetic instructor at a high school or vocational school machine shop? It is a very simple job for a machinist.
As far as alignment goes, all you need is a straight 2 X 4 long enough to reach the front wheel. Set the front wheel straight ahead and put the 2 x 4 against the side of the wheel, as high up as you can, before you hit the bottom of the fender or battery box. Align the rear wheel to the 2 x 4. If you have different sized tires, you need to notch the 2 x 4 one half the difference in size.
I am guessing, but I don't think that sleeve should turn with the wheel. The friction from the bearing seal is probably dragging it with the wheel. Without a detailed understanding of how the axle is assembled in the wheel, you are just shooting in the dark and may end up destroying your hubmotor. Ask Kelly for details on the construction. An exploded diagram? Good Luck.
I believe that you will need to shorten and re-install the sleeve! The sleeve fills the gap between the axle and the wheel bearing oil seal, and is likely to also provide security for the wheel bearing to axle positioning. Operating without it may cause bearing damage and/or wheel alingnment and stability problems. The sleeve should fit securely against the inside of the bike frame, and thusly be prevented from rotating, by that friction fit, when the axle is tightened. (Yes, it will turn with the wheel, due to the bearing seal friction, but if you HOLD it, to overcome the seal friction,the wheel will still turn.) The inside of the seal, and the outside of the sleeve, should be lubricated with light grease. Do not damage the surface of the sleeve that goes inside the seal! This area must remain very smooth, or the seal will be damaged, allowing later bearing damage and failure.--Bob
By all means, reinstall the sleeve after modification per Mr. Curry.
Hopefully, you protected the bearing area from the grinding/filing debris! After the spacer was removed, you need to be certain there is no debris inside the bearing seal area, if there is, use a "Q tip" or similar, coated with oil/grease, to clean and remove this contamination, and re-insert the sleeve, after shortening it to provide proper fit. This sleeve is critical to maintaining proper bearing spacing and wheel position on the axle--that may resolve your "Dragging brake" problem. (Do this spacer shortening carefully!-You may be best to seek machine shop assistance)--Good luck, Bob Curry
I thought I saw dust from axle filings on the wheel in the picture, but wondered if it was just "Mr. Blurycam?"
As far as I know, Kelly doesn't produce the motor.
I should also mention that my Cycle Analyst is showing that I get around 45 to 50 watt-hours per mile at 25MPH with a 150lb load (me).
Wow great job on the conversion. I am wondering about this last statement. How did you connect the magnet to the wheel to get the speedometer to work? I just ordered the Cycle Analyst. I check my front wheel and I don't see anyplace to connect the magnet. I have the XM-4000, so should be the same as your XM-3500.
You can carefully remove a little of the coating on the wheel and use epoxy to mount the magnet. Even silicon will work as and adhesive if you leave it for a few days before riding.
Sorry, but how did you mount the CA console? I assume that the XM-3500 has the same handle bar cover, plastic housing.
Does anyone know of a place in Oregon that might be able to rewind my hub motor for more torque?
Get a bigger controller instead.
it will cost about the same, but give you way better performance than a rewind.
I would suggest a 600A controller.
600A?! I'm not looking to do wheelies here, and it would probably instantly fry my motor. I was thinking a 50% increase in torque by going from 200 to 300A would be good.
The whole problem is that Kelly will not tell me what the motor is rated for, besides "4500 Watts". It is supposedly a 72V motor, so does that make it 62.5A continuous? But it's not watts or volts that kill a motor, it's the amps. Amps cause heating which can melt the windings' lamination and cause an internal short.
yes it would mean the rated current of the motor is likely to be 62.5A continuous.
it will be higher for 30 mins.
the tricky thing is, controllers don't have alot of thermal mass, the way motors do.
so if you buy a 300A controller, beyond 2 minutes, its only good for ~100A.
at that point your controller is in thermal limit, so it becomes a 100A peak controller until it cools.
thats no good if your motor can take 100A for 15 minutes.
a 400A controller would be a closer match, still giving you more peak power.
you can always program a big controller to back off, but you can't make a small controller act like a big one.