***** NOTES from Jay Laifman (JLAIFMAN (at) PNM) at 10/31/95 8:39a
"Don't they all?" I have a warning -- speedometers need internal
lubrication! I learned this the hard way through destruction of my speedo.
For many years my speedo sweeped. I thought it was the cable or cable
housing. I went to a local shop that made me a new cable. It fixed the
problem for quite a number of years. When it started again, I got a new
cable and housing and made sure that the route of the cable did not cause
any excessive bends. This time nothing changed. I shrugged and let it go.
On a long trip a few weeks back, the speedo started making sort of a
slight rubbing noise. I thought I should probably reach under and unscrew
the cable. But, I didn't. Within about 50 miles the speedo just stopped
at a reading of 80 mph - which was not my speed but a result of the
sweeping, and slightly lower profile tires than original stock.
Fortunately there was a swap meet a week later. I picked up an
original guage for cheap that apparently had "sweeping" problem as well.
I had just read somewhere that the sweeping could also be caused by dirt
on the spinning magnet, or the cup it turns (the flat magnet is directly
attached to the cable, and is surrounded [without touching] by a metal cup
which is attached to the needle. The faster the cable and magnet spins,
the more magnetic pull there is on the cup which causes the needle to
advance). I took apart my guage to find that the cam that connects the
cable to the odometer (a direct drive off of a small gear) froze up solid
which caused the cable to freeze up at the speedo end which in turn caused
the cable to snap - so much for my new cable. I was able to construct a
complete good guage from the two of them and now have a working guage --
with lubricated cams.
You have all been warned!
Jay Laifman
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