Dim instrument lighting seems to be pretty common on 928s. There are three
triangular shaped plastic pieces on the bottom of the gauge housing. These
have a chrome-like finish on them, and are what transfers the light from
the bulb to illuminate the gauges, in a fiber-optic sort of way. One of the
reasons that the instrument lighting is dim on many cars is because the
chrome-like finish on the plastic pieces has deteriorated over time. Mine
were more of a dull primer gray color than chrome. The chromed plastic
pieces aren't available separately, so you'd have to buy a whole new gauge
housing to really correct the problem. I experimented with a couple of
different chrome spray paints, but those didn't look any better than the
messed up original coating that I had before I started. The side of the
paint surface that actually contacts the clear plastic is what's really the
important surface, the same as the reflective coating on the back of a
mirror. With the regular chrome spray paints I tried, that surface against
the clear plastic was just gray.
Today I found a solution though. At a local hobby shop I came across Alcad2
chrome paint. This is not like any of that other chrome paint you've
probably seen. Don't let the way it looks in the bottle fool you. It looks
amazingly like chrome plating when sprayed on. The instructions state that
you should use a gloss black paint as a sort of primer under it to get the
proper chrome finish. Since the reflective surface on the three plastic
gauge housing pieces should be facing in towards the center of the clear
plastic, I sprayed the Alcad2 on first, and then the black on top of it.
The area where the light enters and also where it exits the plastic pieces
needs to be masked off before painting. I was really surprised at the final
result. It should work at least as well as the original chrome coating, and
it cost less than $10 to do.
Mike Schmidt