Just for a change, I thought I would share a solution rather than a
problem with the list.
At our club's last tech session, one of the guys had a 80 B with a
speedo that would work for 10-20 miles, then quit. He had taken the car
to 2 of the local shops, with no results but a new cable.
We took the cable loose from the speedo, but left it connected to the
trans. Jacked the rear up, put the car on jack stands, started it up,
put it in third, watched the end of the cable turn. First thought was a
bad speedo. As I picked up the end of the cable to look at the condition
of the square drive end, it stopped turning. releasing it, with a little
encouragement, it started to spin again. Since this was a new cable, it
seemed unlikely that it had a break. Now we new the problem was in the
angle drive or the speedo gear. Both had been previously inspected at
the 2 shops, but somehow they had to be the problem.
Removed the angle drive & speedo gear. One of the other guys looked at
the angle drive & pronounced it fit for service. He said the gear looked
OK too. I looked at the gear, the square socket end looked fine, not
rounded out at all. Teeth looked good, all in all, looked like a new
gear. While fussing with it, looking for some symptom of demonic
possession, I realized that I was turning the plastic gear while holding
the steel shaft stationary.
Apparently, the plastic gear is an interference fit on the shaft, with
no key or other positive stop. When cold, everything worked fine. As
soon as things warmed up, the shaft became stationary, while the gear
turned. Solution is a new gear if one can be found. Home-brew fix that
may work is green Locktite, the version that is for assembled parts, as
it will weep into the gap. Don't know if it will work on plastic. Next
try will be to try to drill the gear & shaft & insert a pin. Not very
confident that this can be done without going to a machine shop. Long
way to frill a very small hole.
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