When I recently performed the brake job on my car-New pads and rotors all around, no sensors, I used all of the same shims, clips and springs; no rattles, squeels,
..nothing.

 

I think the key here is.... You need to have hardware installed. Sometimes brake places don't do their job correctly and skip this step. And if over time you do get a rattle, then you hardware is worn out and needs replaced

 

If you remove the caliper Lexus suggests installation of new caliper bolts@$5/ea.