Odd speedometer behavior

[riderdan]

It's 8 degrees outside this morning, so I haven't tried digging into this at all. Thought I'd ask for expert opinions before digging in to the problem--hopefully it will be 50 on Thursday.

Anyway, driving home yesterday I glanced down to check my speed and saw the speedometer was well over 60, even though I know I was only going about 45. I watched the needle slowly turn past pointing straight down and come up on the other side to just below zero again... I know the issue isn't at the engine end, as the odometer numbers kept ticking up. Shut the truck down and restarted it (can you tell I work in technology? I tried to reboot my HMMWV) and it's stuck there.

Anyone encounter a similar problem in the past, or have pointers on what to check. I'm not the US government, so I'd rather not replace the gauge as a first step

 

[papakb]

Remove the speedo and then use a variable speed drill with a piece of old speedo cable or a squared off drill bit in it and run the speedo and see how it behaves. This sounds like the speedometer is shot to me.

 

[frank8003]

In a Deuce one must run the drill slow in reverse or wipe out the speedo

 

[Big Tom]

When it was cold here in md mine was slow to go back to 0 but didn't over wind . Let temp come up and see, when it's warm it will be be easier to check out and it mite not be a issue.
Big Tom

 

[papakb]

I've never taken an MV speedometer apart but the way most speedos work is the cable turns a rotating magnet and that motion is coupled into the gauge itself and drives both the needle and the odometer. There's a clutch inside that prevents the odometer from running backwards so you can't reduce the mileage reading by running it in reverse. Turning the cable backwards shouldn't hurt it.

 

[frank8003]

I've never taken an MV speedometer apart but the way most speedos work is the cable turns a rotating magnet and that motion is coupled into the gauge itself and drives both the needle and the odometer. There's a clutch inside that prevents the odometer from running backwards so you can't reduce the mileage reading by running it in reverse. Turning the cable backwards shouldn't hurt it.

Methinks that's for cars
I remember Plymouth Valiants running the speedo odometer backwards when backin up.
Thats why it was easy to take "miles" off of them, now no can do it is electronic on the CAN BUS.

 

[joel]

Methinks that's for cars
I remember Plymouth Valiants running the speedo odometer backwards when backin up.
Thats why it was easy to take "miles" off of them, now no can do it is electronic on the CAN BUS.

I wonder if lubrication would fix it(cable, speedometer?

 

[riderdan]

Thanks for all the replies. It's supposed to be 70 on Thursday (and then 32 next Tuesday. Really Kansas?) and I'll see if I can pull it and take a look. I'm hoping for an easy fix, but it's an MV so I'm expecting to have to spend money

 

[joel]

ask the question to the internet