Traderman - whilst I am not an expert ( I am currently trying to decide what brushless
combo to fit to a 34" RAF Crash tender) - clearly your motor
is turing your prop shaft
way to fast. With your motor
spec of 3180 kV and a 14.7 V Lipo - your motor
will be trying to turn your shaft at a speed of somewhere in the order of 45,000 RPM !! Firstly your prop shaft
may not be rated for anything like this speed and secondly any slight mis alignment will likely be generating significant vibration
- enough to cause your problem- have you noticed any?
As to motor
power - the motor
may not be too powerful - but certainly dropping to a lower kV motor
say 1100 and reducing the Lipo voltage
to a 11 or even 7 volt system
might be the right answer......but as I am finding its all a bit suck it and see...