Do's and don't of installing a torque arm?

[mike662]

Hi everyone, this is my first post on here. I have built an ebike a couple of months ago and it has been serving me well. It is an aluminum bike I bought at Costco years ago and I installed a GoldenMotor 1000W 48V rear hub motor on it. So far the bike has been serving me well, but I want to install some torque arms on it. Before I take everything apart again, I have a few questions. Is there anything I should know about the do's and don'ts of installing a torque arm? I would especially like to know whether or not I need to have the torque washers installed on both sides of the dropouts? My idea is to have nut, torque arm, dropout, washer, washer (the extra washer is for helping the off-center hub) hub motor, gears, washer, dropout, torque arm, nut. The reason for this is because I don't have enough room to have all the washers and 2 torque arms on. Is it bad to have the torque arms directly in contact with the dropouts? Do the torque arms need to be perfectly aligned with the frame so that they hold the axle at a perfect perpendicular angle (meaning that when you look at the bike from the back, the torque arm isn't on an angle toward the left or the right of the bike, so that the arm is flat against the dropouts and frame)? Will constantly tightening and undoing and re-tightening the bolts on aluminum dropouts weaken the dropouts? Thanks! Here are a few pics:

 

[dogman dan]

The torque arm can go directly in contact with the dropouts only if it lays nice and flat on the frame surface. If not, you may still need some kind of thin washer, C washer, or even a thick washer to insure good contact between the nut and the frame. Anything that causes an air space in there will cause the arm to eventually deform, which allows the nut to get loose.

Not sure I explained that in a way that can be understood. Looks like a nice clean install now, and it need to be just as clean with the torque arm added.

Not someting wonky with the torque arm laying crooked. You may have to notch the arm to go around a derailur hanger or whatever.