Rolling back speedometers

How do you roll back a speedometer? I have a 55 Plymouth dash going in my 37 Dodge pu and would like to start at zero miles. If I ever get it finished lol.

What is the knurled rod for?

You might want to start with a new speedo. I believe it's illegal in most states to roll one back.

Toad

Your pics didn't show. Can you post one of the back of the speedo? I wouldn't think it would be very hard to do on one that old.

I know, but I don't really care, who's gonna know but me and everyone on the www. LOL.

I think my dad used to hook up an electric drill to the shaft and let 'er rip!

Beercan

Ive never done it,but I was going to say,use a drill also..

I wish I had taken notes or pics when I reset the one in my Willys but here's a video of a Classic Mustang odometer that looks pretty much like what I did.........I'm pretty sure the drill method would take about a month and a half

http://www.youtube.com/watch?v=87kZQkKGSw8

Sure it will make you feel like a crooked car salesman in a plaid suit but it's nice to start out a fresh build at zero miles. Hope this helps.

The drill is so slow, it will take six months non stop to get it back to zero. I tried it one time, in two hours only got about 10 miles.

Taking it apart without breaking anything would be the trick, as I figure the plastic has hardened or turned brittle over the years. Later models have a line that shows up if you tamper with them, I doubt yours will have anything like that as old as it is.

Toad said:

You might want to start with a new speedo. I believe it's illegal in most states to roll one back.

Toad

Click to expand...

Doesn't really matter if it isn't original to the vehicle. ...and it's a rat rod.

We used to have some old speedometers laying around when I was a kid, and we would run them off of the tire on a bicycle (turned upside down). It might be faster to run it forward - depending on where it's at now. If a drill is your choice, and if it is too slow, you need to build some sort of bracket to hold it against a rubber wheel that you've attached to the drill (like in an arbor for a small grindstone, or wire wheel). Set the end of the speedo against the wheel, and turn it on.

Taking it all apart would also be an option, but you'd just need to pull the odometer part of it, turn the wheels back to zero, then put it back together. There may be some pretty small parts that want to go all over the place when you take it apart, so I'd try the other method first.

I did the one in my old Falcon when I was a kid. I think I took the back off and just forced the number wheels around to zero with a pick or screwdriver. It didn't work before or after so I had all zeroes as long as I had it.

Blue

in NH it just states "It is a felony to alter the miliage on an odometer." They don't seem to care what it came in / out of. But the easiest way is to dismantle them and zero by hand.

if it's like most older speedos

You split the housing....remove the two screws on the back and furrel nut to get the unit out of the housing...
Then you pull the needle and loosen or take out the two screws that normally hold the face on.....normally there will be some sort of clip that holds the tumblers (numbers) in place..and or there will be tabs that sit over a rail of sorts to keep them aligned.....pull the tumbler forward off the rail remove it and pull it away from the housing...then you can turn the tumblers over to what you want it to read..zero's I guess but make sure the tabs that slip over the small rail will line up.....drop it back into the housing so that the tabs go over the rail and it will seat on the drive gear....Bob's your uncle, Fanny's your aunt and Dick's your best friend......reinstall the face....push on the needle....and reassemble the case....all of this must be done with finess.. not like a bull in a china shop....easy does it....

forgot to add....you didn't hear that from the old Sarge!!!

A friend of mine just rolled back the speedo on his motorcycle. He tried the drill method and it barely moved. IIRC he went to an electronics store and bought a small DC motor for a couple of bucks. It spins at a ridiculously high RPM. Rolled the speedo back 7000 miles in about 2 minutes!