instrument fog

[Zombie Master]

1984 R100
So I often have some moisture in my speedo.

After running several hours it will dry out.

But it returns again.

Is there a vent hole?

Where might that be, if there is one?

Could it be partially blocked?

Has anybody done a mod, for better instrument ventilation?

Thanx

[SteveD]

Are you using LED lights? I found the fogging was much worse.
Maybe a small bag of silica inside for a trial?

But to answer the question, maybe the way to go is to prevent the moisture getting in? Is the rubber gasket too compressed after 40 years?

[barryh]

Fogging is quite common from what I can gather. I've tried silica gel and it did work but not for very long. Over time the fogging seems to attract dirt. When I had my speedo apart to fix the ubiquitous slipping gear wheel I cleaned the glass and what a difference that made. The tach now looks positively scruffy beside it so I'll have to clean that as well. Not a trivial job because I have to uncrimp the bezel.

[mkj]

If you park outside in the rain cover the clocks with a plastic bag, stops the fogging.

[melville]

If it's not raining where ZM lives, then the relative humidity is nearly always 100%. I had the same issue when I lived on the coast.

[mkj]

In that case why not fit a little 12v computer fan, would do the job I think and you do get some little one.