From:Dave Hennessey
Subject:RE: RE: RE: Danny's Speedometer Woes Date:Tue Apr 10 01:06:14 2018
Response to:1393
I contacted my speedo expert out in British Columbia for the straight dope on these speedos.

The 1958 to 1961 speedo is shown below. The 1956 and 1957 were the same except the background of the 10ths digit on the trip odometer was red.

1961 and earlier
1) The connection on the back of the speedo was a female "hole".

2) The speedo read 60 mph when the cable turned at 2000 rpm. Also known as a 2:1 ratio speedometer.

Police speedos during this period looked almost the same - no visible "Police" markings, but there were 3 differences:

a) Police units had 1 mph markings on the lower face, and there was a 65 mph marking. Civilian units had 2mph markings, and no 65 mph marking.

b)Police units had the needle squeezed to a tighter point than civilian units.

c) Police units were calibrated to read between 56 to 59 mph when the cable was turning 2000 rpm. Civilian units were calibrated to read between 62 to 65 mph.

1962 and later
1) The connection on the back of the speedo was a male "protuberance".

2)The speedo read 60 mph when the cable turned at 1000 rpm. Also known as a 1:1 ratio speedometer.

The black-faced 100 mph "Police Special" commonly seen speedo started in 1962.


The reason for the change from 2:1 to 1:1 was that the later speedos would last longer than the earlier ones because the innards were only turning at half-speed.

The early/late transmissions used a different gear on the countershaft, and a different removable drive unit to effect the change in cable speed.

The change in the connection on the back of the speedo was done to prevent mismatch of speedo/transmission.

Thus the early/late cables were different - the early cable has a male connector on the speedo end, while the late cable has a female connector. Both have the same connector (female) on the transmission end.

A handlock was available on any police speedo. This was an electomagnetic unit built into the speedo, and required an extra button on the handlebars.

Due to the scarcity and cost of 1961-earlier speedos, some modern reproduction speedos have the 1962-later male protuberance, but operate at a 2:1 ratio. To use one on a 1961-earlier bike (more correctly, a bike with a 1961-earlier transmission), you will need to change from the early to the late cable.

Perry pointed out that Harley-Davidson had Stewart-Warner make some of these oddballs way back when (1970's ??) as spare parts. If you see a NOS still-in-the-box for sale, you'd better check that part number carefully.

More than you ever wanted to know...