I have just washed a load of black muck out of my Smiths mechanical speedo, which has been very erratic even after fitting a new cable. It now rotates freely (the main bearing at the back was rather stiff before). Now what lubricant is required? Grease, light oil, engine oil? I noticed that in very cold weather the needle reads very slow for a few miles, so thick lubricant is probably not indicated. Maybe some sort of light machine oil?
In message , Asolepius writes
I believe you should use Graphite dust. (As you would with a clock). As far as I know, any oil will slowly evaporate leaving you just as badly off as you were before.
I'd say typewriter oil is ideal for that kind of delicate mechanisim, it's what i'd use. However, i'm not sure you can buy it any more. It's like 3-in-1 only about half as thick, and a very old bottle. 3-in-1 would probably do, you only need a very light smear on the cogs etc, just to keep them turning.
Alex
I would say that the black muck which you washed from the mechanics was from oil feeding up through the speedo cable itself and solidifying.
All they have is a tiny spot of grease on the pivot points which need lubrication. Oil does evaporate eventually.
Make sure you wash the cable and that it has something to restrain the oil from travelling through to the speedo. Usually a felt seal.
I believe that sewing machine oil (which you can still get) is the same stuff as typewriter oil. But Chris is right - you shouldn't use oil at all. Graphite dust lubricates without drying out to a varnish eventually. The black muck that the OP washed out of the speedo was probably the original graphite dust mixed with oil or grease that has travelled up the cable.
Jim
Thanks folks - yes I pretty much sussed that the black gunge was graphite (at least partly). Not sure what I can do about the cable as it's a new one. I have cleaned grease off the top few inches but I can't see how I can prevent it creeping up again.
We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Asolepius" saying something like:
It generally doesn't. Grease is a bit too thick, use EP90.
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