How to Use a Vintage Car Speedometer on a Chopper?

[AbyssmalTailgate]

Just an idea, but I was wondering if anybody has ever used or tried to use an old car speedometer on their bike? I know the speedometer's gearing ratio, wheel circumference, and rolling distance all factor into a functional speedometer; however, I figure if I need one of these things to be legal, it'd look cool to use a vintage dial from an old car.

My thoughts on the topic right now is that I may have to "re-gear" the car speedo to match the bike's specs. My plan is to purchase a functioning speedometer that matches the specs for my bike as well as a vintage speedometer from a classic, American car/truck (something that looks good), then replace the guts of the car's dial with those of the new one geared for the bike. I can't really see why this wouldn't work.

Any thoughts on this idea?

[BuddhahoodVato]

A lot of work,
steward warners old housings are the same as scoots.

[AbyssmalTailgate]

A lot of work,
steward warners old housings are the same as scoots.

Kinda what I figured... think it'd be difficult to match the gearing between the two speedos?

Also, thanks for the tip on Stewart Warner!

[DrFxr]

As BuddhahooVato suggests, if you can find a proper motorcycle speedo that is the same size or smaller than the speedo you choose, you can swap the guts and save yourself from the gear mathematics. The gauge bezels are press-fit, but you can GENTLY pry around the circumference of the backside until it is un-peened. Don't rush it. If it does not want to unroll (as many SW's are hard to do this to), you may cut small reliefs in this peened edge with a dremel cut-off wheel. Just be very meticulous, do not cut onto the side of the bezel or you may see it after, depending on how you mount it. Also keep in mind the bezel is plated, so too much aggressive prying can crack the finish. Most speedo needles typically come off by twisting and pulling up and away from the gauge GENTLY. They're not screwed on, they're just press-fit onto the shaft. The face attaches to the mechanism with 2 small rivets, so you'll need 2 more to re-attach the mechanism to the new face. An adapter plate may have to be made if the rivet holes do not line up with the new face. You can do this with a thin piece of aluminum and some panel bond or similar adhesive. The needle will go back on by gently pressing and twisting counter clockwise, it to the "0" position. Re-assmble the gauge/lense/bezel, place it face down on your bench on a thick piece of leather or similar "chrome surface preserver", and peen the bezel back over the housing. Another tip.... if the paint is flakey inside of your gauge housing, strip it out and re-paint it. Nothing sucks more than taking all the time to peen that bezel on and flip it over to find crap on the lense. Hope this helps, good luck with the project!

[AbyssmalTailgate]

Sounds like you've work on speedo gauges before? Thanks for the detailed write up! Definitely helps give me a better idea of what I'd need to prepare for. Suffice to say, I'm really tempted to try this...