I recently had the displeasure of re-installing the plastic side
vents on a restoration project. Honda should have put threads on both
of the studs. After wrestling with some hardware store push on speed
nuts I gave up and carefully threaded the rear stud of the vent. I
had originally thought all the studs were plastic, but on this car
they are both brass.
Many times I will install emblems with a piece of snug fitting
tubing, this works particularly well for cleaning & waxing as the
parts can be easily removed and replaced. In the side vents case not
enough room to get the tubing onto the back stud but worked well on
the front stud.
I carefully threaded the studs to 4mm x .7 pitch using a tiny die
from a Hanson T&D kit.
Miles