When I refurbished my Norton Roadholder forks, I bought a complete service kit which included the top and bottom bushes, circlips, oil seals and paper gaskets (washers), along with the fibre washers for the drain screws and damper rod screws.
During dismantling, I noticed that the bottom ‘face’ of the oil seals had a similar surface area to the top. When I came to reassemble the forks, I was concerned as the bronze bush goes in first, then a paper washer and then the oil seal…open spring side down. The underside of the seals in the kit, has what was essentially a sharp, knife edge, which would be resting on the paper seal. When I tested it, the seal appeared to curl up and I was concerned that once it was tightened up with the slider extender, it would cut through the paper…and you don’t want bits of paper jamming your forks up.
I looked at various step-by-step guides, most said bronze bush, paper washer, oil seal. One suggested bronze bush, oil seal then paper…which could work. Another never mentioned the paper washer. Having discussed it with a bike pal, we came to the conclusion that bronze bush, paper washer and oil seal option was probably right.
I retrieved the old seals from the bin and quickly found some on line that matched the profile of the original ones. These give plenty of surface area to bear down on the paper washer without cutting it. You’ll see what I mean from the photos; the bottom of the seals is shown on the right of each picture. Note that most suppliers only show the top of the seals for some reason, so you may have to ask. The ones with sharp edges were probably fine, but I wasn’t going to take chances for the sake of a fiver or so.
Mine came from Brit Bikes UK, part 06-5483.