There are two types of Speedo drive gears for the BS175 - a metal one and a later plastic one. A BS service letter I have makes reference to a modified speedo gear early in the poduction run to cure instances of the large gear seizing on the spigot in the brake panel. It doesn't mention any change of part number or material, but I assume that this the origin of the plastic gear.
My query is, are the two types freely interchangeable? I have a new metal gear but my 175 originally came with a plastic gear. Can I use a metal gear in my brake panel without changing the smaller drive pinion? Has anyone tried this?
Graham
