Speedometer question?

[5B Steve]

  What would be the reason that the speedometer would just stop working I have a MCI-5B?  Is it an electrical

  problem , or did the cable break? I know with time something has to go south. 

   Thanks!

   Steve 5B.....

[bevans6]

The speedo is driven from a magnetic sensor that counts the rotations of the driver's side brake drum - should be about 3/16" gap from the 1/4| bolts that it senses to the sensor.  From there a wire goes to the speedo via the main electrical panel.  So it could be a wire break, a sensor out of adjustment, a fuse (unlikely) or a bad speedo head.

Brian

[eddieboy]

My '62 PD4106 also has a non workding speedo.  I check the drivers drum and it has several holes around the edge of the drum.  Is that for screws to be sticking out or is the sensor counting the holes???
Ed

[lostagain]

The drum should have bolts screwed in to it with the heads facing out toward the middle of the bus for the sensor to read as they go past. The sensor is adjustable for distance to the bolt heads. If the distance if off, too close or too far, the speedo needle is erratic. When you finally get it right, the needle is nice and steady.

eddieboy, maybe your speedo reads off a speedo drive on the transmission. And something is off, stripped, or broken.

JC

[johns4104]

My 4104 has a sensor on the transmission.
Some times my speedo works and most of the time it dosen't.
Occasionally it will bounce up and try to work and go back to zero.
I can't decide if its the sensor or the speedo.

At any rate it keeps the milage down on my Bus.

John

[06 Bill]

Steve,  My 4106 has two small magnets mounted on the brake drum in two of the holes you mentioned @ 180*
apart. There is a small pickup coil mounted on a bracket set at about 1/16" away from the magnets. Turning
flexes the wire from the pickup and breaks. If you find you have a wire prob. locate wire so as to be vertical which
gives it a twisting motion instead of a bending motion. No prob. since this mod.    06 Bill

[5B Steve]

    Hey Guys,

    Thanks for all the feedback you have put forth. I'll check it out!


    Steve 5B.......