Hi there, thanks for your reply.
the pivot bolt was a bit loose, and my swing arm plate has a 5-6mm gap allowing the plate to move.
If i was to do it this way(loosen wheels nuts, tighten brake arm nut) then the whole brake plate will rotate anticlockwise slightly due to the fact that my swing arm slot is wider than the bolt. it was like this when i bought it and its now wider. Ive no idea why they make these swing arm slots wider than the bolt (by about 3/4mm) This to me seems like a flaw. SO. If i did it the way you said Arizoni, then the pivot bolt would be on the high side of the swing arm slot meaning that when you apply the brake, it will want to move clockwise - or forward. (I'm going to weld a steel flat bar closing this gap in the swing arm. THis is the problem i think and i know its happened to many RE riders.)
So what i did was:
loosened everything off.
set my snail cams tighter, as they needed another notch.
pushed the pivot bolt down leaving a 5-6mm gap between this bolt and the high side of the swing arm slot.
tightened the big hex nut a little - finger tight really.
tightened the pivot bolt in brake plate a little bit with socket - just a little to stop it moving.
now all thats in place, i tightened the wheel nuts tight.
then i tightened the brake arm rod nut, like you said above
then tightened the pivot bolt nut pretty tight
then loosened off the brake arm rod nut.
took for a ride and all sweet.
its all about that gap in the swing arm slot.
This will explain why when theres more weight on the bike its more prone to happening and also when going up hills.
i betcha if i weld a flat bar closing up that gap, this will never ever happen again.
If I'm right, i think RE should look at making that swing arm slot gap/pivot bolt snug as a bug in a rug. For something that has so much force on it, having a gap, moving parts etc. i don't think it makes sense. I think i may go NUTS and get a locking nut and a spring washer, as well as welding a bar to close that gap.