speedometer rubbing
Posted: Sat Sep 30, 2017 10:10 pm
for many years, once I got over about 30, needle would go over to 80 or so, fluctuating 10-15 mph.
odometer is fine, except for the larger tires I put on it in the 70s, but that's another story.
opening it up, I see there is no physical connection between the cable and the needle:
the needle is connected to a drum that is held at zero by a spring,
the cable is connected to 2 pieces 180 degrees apart, each in the shape of a "U," with the edge of the drum sitting inside of the "U":
https://www.dropbox.com/s/bd13znxzo11p2 ... g.jpg?dl=0
I guess under normal conditions, the rotating "U"s create a magnetic force, which causes the drum to overcome the spring tension by the proper amount.
The problem: I don't know if you can see it in the photo but, periodically throughout the rotation of the "U"s around the drum, part of a "U" momentarily rubs on the drum, creating extra force against the spring, so 35 becomes a fluctuating 80.
I've got another speedometer head, but its odometer is about 40K off.
Thinking that I've got nothing to lose, maybe I could sand down the part of the drum that is catching. maybe have the vacuum going to try to keep grit out of the odometer gears. Suggestions?
odometer is fine, except for the larger tires I put on it in the 70s, but that's another story.
opening it up, I see there is no physical connection between the cable and the needle:
the needle is connected to a drum that is held at zero by a spring,
the cable is connected to 2 pieces 180 degrees apart, each in the shape of a "U," with the edge of the drum sitting inside of the "U":
https://www.dropbox.com/s/bd13znxzo11p2 ... g.jpg?dl=0
I guess under normal conditions, the rotating "U"s create a magnetic force, which causes the drum to overcome the spring tension by the proper amount.
The problem: I don't know if you can see it in the photo but, periodically throughout the rotation of the "U"s around the drum, part of a "U" momentarily rubs on the drum, creating extra force against the spring, so 35 becomes a fluctuating 80.
I've got another speedometer head, but its odometer is about 40K off.
Thinking that I've got nothing to lose, maybe I could sand down the part of the drum that is catching. maybe have the vacuum going to try to keep grit out of the odometer gears. Suggestions?