Thanks Sandro I've seen that, might try that if I can't find anything else but threaded would be so much better. I might just weld in a piece of metal and then drill and tap it. IMO that's easier than all the hassle to make that split wedge thing work. It really wouldn't work on my mirrors anyway as I don't have a "nub" to cut a notch in to to keep it from spinning.
My mirrors are mounted "OK" currently, as in they are attached and not falling off and I can see out of them. But they move way too easily and I can't position them correctly. The mounting system it came with didn't work at all. I did the rubber trick which is better but I can't pull them out away from the grips at all and it's causing rubbing on the throttle. It's fine now but the throttle does not spring back on it's own power I have to do it manually. No problem now but I lose the purpose of the double cable on the throttle(safety issue).
I really just want to thread them on.