Did bought a cool gauge today, a Stewart Warner 5” Police Special 100 MPH. I think it from 35/36 and no clue on car or MC. Price was decent. Seller said he bought it over 400 US but I did not pay that. I has not figure out how to deal with rest of the gauges. Did S/W had this beige series on other gsuges on the 30’s ? Will fit my 5W 32 coupe good maybe and I plan a Indy car dash, sterring wheel and parts will not be later than 39. Ideas of rest of the set-up !?
You have to be a bit careful with speedometers as the motorcycle versions don't usually use the same cable-turns-per-mile ratios as the car units and there can be multiple ratios depended on OEM use.
Anyone knows how to read serial number if for a car or not. Seller told me mid 30’s but the few I seen has need described both as 35/36 or 52 or even 55.
Here's the Police Speedo in my sedan. Mine was NOS when I put it in. Mine has a 1939 date code on it. Seems yours has a February 1947 date code on it. Many years ago I gave that SW date code data to Dave Mann for his website. Stewart Warner changed up the look a little as they kept making these for Police forces. I also have a black face one that I think goes to 140 or 160 (I forget). They were equipped with a ****on on top that the cop was supposed to push and it froze the needle at the top speed during the pursuit. So, mounting it flat in a dashboard like I did is not really how they would work. Motorcycle versions looked slightly different that your car version.
Oh great so I has a car version. If my is 47 I cant see much of design is changed ( can you ? ) The black ones you talking about, what year was that produced ? ( car or MC ? ) I was into as you, this speedo and and black S/W in a Indycar dash.
Not sure what year my black face Police Speedo is, but I think in the fifties. I don’t own any motorcycle speedos, but have seen them. They look similar at a glance but are different.
Harley Davidson 1:1 work. I used one in my '34. They're inexpensive as reproductions. I bought mine from JP Cycles. They are also available as 2:1, don't use that ratio.
You will probably need to change the speedo cable gear (turtle) to fine tune the reading on the speedo.
Check the odometer reading on a measured mile, then a ratio adapter can be made up that attaches between the turtle and the speedometer cable to calibrate the speedometer if it's way off.
Standard automotive speedometers are calibrated for 60 mph at 1000 rpm. A 3.78 gear with 30" tire will turn the driveshaft 2450 rpm at 60. The speedometer drive ratio would need to be 2.54, 4.11 axle would use a 2.76 speedo ratio. You need to know your axle and the number of drive teeth on transmission shaft to figure which driven gear you need. If it's the factory "32 transmission, speedo gear options are limited, so the add on ratio adapter previously mentioned would be a good option.
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