Motor cycle speedometers in cars?

Just curios has anyone ever used a motorcycle speedometer in there car with any success? And what problems did you find ? I would like to use a large Harley speedometer


They told me it couldn't be done... So I'll try it.

 

Good luck.

 

Why not? If it's cable driven you just need to figure out the revs per mile that it is geared for and duplicate that. Who knows, may be the same as automotive standard ratio. Even if electronic, same basic idea applies.

If you try it, let us know what you find out.

Ray

 

i don't see why not you will have to find some one that has reduction gears to correct the speed and to change the cable ends if they are different. it used to be easy as meters in taxis use to be cable driven.what year Harley speedo in what make of car?

 

It's a model a with a 305/350 combo


They told me it couldn't be done... So I'll try it.

 

Here's your Harley info

2:1 Ratio Speedometers: Fit FL models with transmission-driven speedometer drives from 1947 through 1967 and Sportster, FX and FXR models withfront wheel speedometer drives from 1973 through 1990 except softail and 4 speed FXWG models. (5/8-18 nut on cable)

1:1 Ratio Speedometers: Fit 4 speed FL and FX models with transmission-driven speedometers from 1968 through 1983/ (5/8-18 nut on cable)

2240:60 Ratio Speedometers: Fit all softail and 4 speedFXWG models from 1984 through 1990 and 4 speed FL models with front wheel speedometer drives from 1981 through 1984. (Requires speedometer cable with 12mm nut)

So once you find out what Harley yours fits, then you can figure out what ratio you have.

Then you can intelligently decide if the Trans will drive it.

 

Harley used mechanical speedos on everything through '94, by '96 they had gone to all electronic. The 2:1 units are the most common.

Keep in mind that the 'ratios' given have to do with the speedometer drive; this takes in the factors of tire cir***ference for front wheel driven units or transmission/final drive ratios for the trans driven ones. I haven't done the math for the 2240:60 units (which I don't think would be practical to use), but the other two I have. This had to do with trying to find a 'custom' replacement for a jap bike, where the ratios vary yet more from brand to brand (in this particular case, the OEM ratio was 2.9:1 so none of these would result in an accurate speedo). Anyway, the 'calibration' works out to 782 turns of the speedo cable per mile for the 1:1 units, and 1564 turns for the 2:1 units. Most automotive speedometers are designed for 1000 turns per mile (although this can vary by about 10% +/- depending on make/year), with the speedo drive in the transmission geared to give that result taking into account the rear axle ratio and tire size. So some sort of adaptor would likely be needed to get a 'correct' cable RPM for accurate speed readout.