New ProKit901 - request help for bent spacer tubes on rear installation

[Davidberg]

Hi all!

I'm a newbie here, purchased my first ever GM kit a week ago. It's a ProKit901 rear version, it was installed on a steel MTB frame. I've downloaded the "Pro-Kit User Guide" and carefully studied it since I it was my first try to electrify a bike. All the installation went fine, and tested the bike which was great and had a smooth run.

However, as the user guide states "Tighten the bolts; make sure it is very tight. This is for safety reasons and this is a very crucial step to build a good eBike. The torque of the motor is very powerful, which is why you must make sure the bolts are tight enough to handle it.". So I tightened it as much as I could - and it seems this process bent the spacer tubes on the axle (please refer to the photos below). How on earth could GM make these crucial parts out of aluminium? My question is are these spacer tubes replacable? I've some machinery knowledge and if they are easy to take out from their place, I can lathe these tubes out of stainles steel to whitstand the pressing force of the nuts on the rear dropouts. Or at least use some short stainless steel tubes strong enough for a replacement.

Any comments are welcome!

Regards,
David

[Bikemad]

Hi andto the forum.

The right hand tube should just slide off the axle, but replacing the left hand tube entails removing the connectors from the wiring to allow the spacer tube, washers and nut to pass over the end of the motor's wiring harness.

Thick walled stainless tubing sounds like a very good plan to me, although it will be difficult to determine the original length of the tube before it was shortened during its impersonation of a concertina.

Alan
 

[GM Canada]

Wow, nice job tightening the nuts!

I guess you realize it was too tight now. Be careful of this as you could just as easily stripped the axle threads. You can easily replace the tube with something from a local metal supplier for very little expense.

Gary

[Davidberg]

Thanks for the replies guys! Oddly enough the left hand tube stayed intact, so I can determine the length easily. Must to be careful of the wall thickness of the new tubes I'm planning to machine because if I make it thicker, chanches they are gonna jam into the slot of the bearings on the motor side. As I've made some research, I guess chromium-vanadium steel alloy (high-speed steel M36 or M42) might be the best for this case (this is the material used in saw blades, drills, milling cutters, high quality kitchen knives and swords) altough it requires diamond coated machining cutters to mill it). It isn't cheapo but the end result will be the strongest part of the bike 

I'll post pictures (and a machining blueprint if somebody facing the same problem) later!