There is a distinctive swirley helical gear on the early models, to drive the speedometer.
Later models do not have the gear. The bushing in side is replaceable, the lower picture at right has a gear missing the bushing (the right side).
The early gear bushing is 35787-52 to L72. The late gear bushing is 35787-73 from L72 to 1984.
There were some differences in K-models, but the early gear will retrofit.
This page will be updated later with what to look for as this part wears or fails. |
 The left countershaft has a spiral gear as part of the low or 1st gear. It drives the speedometer on 1952 to 1972 models. The right countershaft is what would be used on 1973 to 1984 Iron Sportsters, the speedo is from the front wheel.
 The 1st, or low gear is next to 3rd gear. It drives the Mainshaft with the greatest reduction ratio. |
Sportster_35750-54_Countershaft-low-gear_1952-1972.jpg
Sportster_35750-73_Countershaft-low-gear_1973-1984.jpg
In order to get the dogs to look better some shady characters grind the tops. The gear on the left has the dogs ground down, note the silvery tops.
It makes them flat but they are shorter.
The dogs being shorter they don't engage as deeply, so it might pop out of gear. If the dogs are worn, buy a new gear.
