Magic Pie Edge disc brake rotor bolt problem

[Jfs]

I am a new ebiker in Boston. I've just bought a Magic Pie Edge to replace a failed front mounted gearless hub motor.  I've hit an installation snag: I removed my 160mm disk brake rotor from my previous hub to move over to the Edge, but the bolt sizes are different. The Edge holes are bigger. I took the Edge wheel to two bike stores to find bolts that fit, but they had no solution: standard disk brake bolts are 5mm. I took the wheel to Home Depot and found 6mm bolts that do fit but they are 12 mm long and I worry they will damage the aluminum housing. And then I discovered that the larger bolts don't fit through the holes in the Shimano 160mm rotor!
I'm going to try to redrill the six holes on the disk rotor a bit bigger so they take the 6mm bolts. But is there any danger in using ordinary bolts? Can they puncture the housing?  Strange to me that GM would use non-standard bolts, and then not supply them with motors they are selling. I assume I'm not the first person with this problem?
Frustrating start!
 

[Bikemad]

Hi andto the forum.

My rear Magic Pie Edge uses 5mm bolts to secure the brake disc, but 12mm long bolts are slightly too long for mine as they would touch against the controller.
The rear brake disc mounting fan assembly has a steel insert where the 5mm threaded holes are:


But I suspect that your brake disc bolts directly to the cast side cover of the motor, and 6mm bolts were probably used to provide a more secure fixing into the softer aluminium threads.

I suggest you check how far the bolts will thread into the holes before they begin to bind, and if the gap between the head of the bolts and the side casing is larger than the thickness of the brake disc, then you will need to use slightly shorter bolts or add washers under the heads of the bolts to ensure they will clamp the brake disc correctly.

Although you may not be the first person to experience this problem, you are definitely the first person to mention this specific problem on the forum. 

Alan
 

[Jfs]

Thanks, Alan, this was helpful. To avoid damage from 12mm length bolts, I found 6x10mm hex bolts at another hardware store and used a washer as well to be safe, and I managed to drill the holes in the disk rotor bigger so they would take the 6mm bolts. That did it. I was able to mount the disk, which matched perfectly with my brake, and I had my first Magic Pie Edge ride yesterday. smooth, sufficient power for me, and silent. Much better quality ride than the Leafbike Motor I bought with the rig (and which soon failed, with what I think were Hall sensor problems from spaghetti wiring). I love the plug-and-play integration on the MP after weeks of splicing, crimping, and ill-matched connectors.

I also managed to get into the MP settings with the USB cable and dialed back the acceleration to 50 percent and lowered the top rpms to 250 to reduce spinning out at starts and to save battery and avoid overheating. This per Gary Salo's guidance in the very good videos from GM Canada.