:? y'a pas une fiche de montage non?
 
enfin bon, y'a pas de mystère, le but n'est pas de solidariser fix et HP, mais hp au support, via la fixation!
 
tu fais le trou pour le HP (ou pour le "siege" qui est à gauche sur la photo), tu poses le HP, tu mets la fix (de droite) dessus, tu mets les vis, et o miracle, ça tient

MIDRANGE MOUNTING
Q Caution, only for RA16.3 Set
The RA50 dome midrange units come with two different mounting adaptors,
one suitable for flat surface of flush mounting, the other for angled mounting
inside a 85mm OEM speaker cutout in the dash board.
Q Remove the panel you are going to install the RA50 dome midrange unit
and check for proper clearance behind it. Flush mounting of the midrange
speaker needs at least 31mm clearance to the backside. Make sure there are
no obstructions behind the spot you choose.
Q Mark the centre of the spot with a felt tip market and remove the panel.
Q Predrill a pilot hole with a 3mm drill bit. Widen up the hole to become
75.5mm in diameter, using either a jigsaw or a hole saw attachment for your
power drill.
Q Mount the four metal spring clips to the mid/range unit, placing them into
the small grooves / recesses on the front rim of the RA50 unit.
Q Connect the mid/range speaker to the extension wire that goes to the
crossover.
Q Mount the trim ring of the grille with four screws on top of the hole you have
cut before and insert the dome midrange unit into this hole, by pressing the
metal clips together.
Q Attach the metal mesh grille to the trim ring, and remount the panel to the
vehicle.