Over the past few years, I've acquired several of these from different years and after examining them, noticed quite a few differences. Most are minor or cosmetic, but some are major. It's pretty common knowledge that the brake shoes are the same for all years and that any plate will swap into any wheel, but that's about the extent of the published data. I'm going to "fill in the blanks", so to speak. If someone acquires a separate brake plate without a wheel, this should help them I.D. it, and if it's missing some parts, you'll know which ones can be used.
So, I'll start with a picture history of the plates, mainly showing the fronts and the cosmetic changes that occurred. The first version was used from '70-'73. It is the most "plain jane" of the lot, with no added extras for checking brake shoe wear. It is the only plate that has it's full part number cast into it .....
The next version came along in '74 and was used up through '77. This one's easy to identify because of the electric brake shoe wear switch it had. The beginning of the part number was changed to "447", which is to be expected. This was the year the "447" bikes started. The full part number was no longer cast in the plate, only part of it .....
Mid to late '77 saw the same "447" plate being used but with a few mods. The electric shoe wear switch was eliminated. The casting was still there but the hole was not drilled and tapped. The bracket for the switch wire was cut off as well. A shoe wear inspection hole with a rubber plug was added to the top of the plate. From the machining marks found on the inside, it appears it was drilled. It was labeled with a foil sticker .....
In '78, a new cleaned up casting was introduced. The electric switch related parts of the casting were eliminated and the shoe inspection hole, along with it's label, were now cast in. The part number changed to 1T3-25026-00-00. Again, it was only partially cast into the plate. This plate was used from '78-'80 .....
So, I'll start with a picture history of the plates, mainly showing the fronts and the cosmetic changes that occurred. The first version was used from '70-'73. It is the most "plain jane" of the lot, with no added extras for checking brake shoe wear. It is the only plate that has it's full part number cast into it .....
The next version came along in '74 and was used up through '77. This one's easy to identify because of the electric brake shoe wear switch it had. The beginning of the part number was changed to "447", which is to be expected. This was the year the "447" bikes started. The full part number was no longer cast in the plate, only part of it .....
Mid to late '77 saw the same "447" plate being used but with a few mods. The electric shoe wear switch was eliminated. The casting was still there but the hole was not drilled and tapped. The bracket for the switch wire was cut off as well. A shoe wear inspection hole with a rubber plug was added to the top of the plate. From the machining marks found on the inside, it appears it was drilled. It was labeled with a foil sticker .....
In '78, a new cleaned up casting was introduced. The electric switch related parts of the casting were eliminated and the shoe inspection hole, along with it's label, were now cast in. The part number changed to 1T3-25026-00-00. Again, it was only partially cast into the plate. This plate was used from '78-'80 .....