thanks man , next one on the list is the arrma notorious : i already received it and ... modified it ! lol ! i couldn't help myself !

arrma put red loctite on the motor pinion : it was really tight ! so i heat it with a 60w welding iron and could slide it with a big flat screwdriver

i should have done it this way : put out the screw and go out for a bash !!!

Fasteners can get complicated but here are some generalizations that may help.

a soft screw (for example alumuminum) is screwed into a soft thread that is clamping or pushing on a hard piece of steel. Threadlocker or gaskets or whatever add a little or allot of friction through expansion, bonding or a number of methods. The point is to add enough friction to the threads so that as things wear or vibrate they dont come loose and back out from the vibration or clearances that get created. I mention hard and soft materials because soft materials have a higher friction for every degree of rotation than hard materials. Obviously lubricants lower friction. Hard materials go from 0 to full torque in fewer degrees of rotation than soft but usually creat a higher clamp force.

lets cut to the chase. If you have a tip on the screw it will wear and round creating a clearance over time making is susceptible to vibration. If your threads are wet they have lower friction. I dont suggest throwing dirt into your threads but in a pinch....you get the idea. If you create a high prevailing torque with threadlocker or anything else you will minimize problems from wear. but you dont want to add so much friction that you have to damage the materials to remove them. Its not the glueing action you are looking for its just the high prevailing torque in the functional part of the threads that minimize the damage from vibration.