Alternator type terminal

Hi,
I 'm an italian student(then excuse for my english)and i've a problem with
my alternator(120 ampere installed on a Lycoming 360);my problem is the
broken of the wire on the terminal of my alternator,the terminal is intact
but the wire result as cut.
The reason for me is the high vibraction in the zone of connection of the
terminal on the alternator and I don't know if the broken owe by the
rigidity of the wire(the size is for the positive 4 AWG and negative 6
AWG,the type of the wire is Raychem for aereonautical application)or by the
wrong crimp.
I wont ask at you that type of the terminal is indicated use in this case?(I
utilize a Amp PIDG terminal form square);exist other possibily cause?
Thank you in advance