Guys epoxy is ONE of the solution, as well it is not the best but for hundreds of person it worked and still work today.
Personally i never saw any axel reaching 121 celsius!!! even if it would happen, the stator wold be like 200 celsius or cooked!
Yes epoxy become softer at high temp like most of the epoxy.
To answer the question about aluminum to steel, the bonding on aluminum is better than steel according to the original spec from 3M and the bonding strengh will always be the weakest surface so oif bonding aluminum to steel, the steel is the weakest, not by far but it is.
Problem happen when people use epoxy as a filler. the DP420 or 460 are structural epoxy but they aree optiized for a given thickness and too thick epoxy layer between surfaces is not recommanded as well.
Bolt and epoxy is the best solution. bolt can loosen too over the time with temperature variation and since most of people dont really ensure that the torque theu use to tighten is the proper torque, the bolt have higher risk of loosen. The combination of bolt with epoxy help to compensate that.
Clamping torque arm is a good solution as well but since it would require machining or drilling in 3D instead of 2D to get the hole and thread for the clamping bolt would make them to cost twice more because that the laser cutting machine that make them in batch can not work in 3D but only 2D.
Even if people are ready to pay the extra i would agree to make a batch of these as well but from now most of people are satisfied with the last version.
Now let's get back to the original subject wich is IS only one torque arm is enough!
My answer to that is NO, that's why i'm selling them in pair!
btw to my opinion, ALL T-A should be sold in PAIR !
The most popular M14 size axel just can't take all the torque people use or will end out to use when they will discover they want more and more power. before selling these torque arms i was tired of repairing broken axel from people that used only one torque arm and that they twisted their axel making it no longer usable. Plus, twist and breaking one side of the axel can result in severe injury after you loose the wheel!