Hi Hal, First a question....... Is that a seal or a bearing still sitting on the bearing race? It also looks like the bearing race is becoming worn.
I just completed rebuilding the last 40 hubs in stock and discovered a 100% failure rate with the current production hub [you don't have the current version]. Because my rebuild price was based on a "rebuildable hub" exchange program, I won't be able to credit the current production hub after Jan 2009. The reason the current version can not survive the rebuild process centers around 2 major engineering glitches. For some reason, which I don't understand, the current version has deepened the bearing cavity and added additional spacers and bearings on both sides of the hub. Adding additional #6901Z bearings is something I am puzzled about, because I have never replaced the #6901Z bearing unless someone over-tightened them and caused the center to crush the outer bearing housing. I asked Whizzer to install a hard spacer between the bearings on the early clutch to avoid damaging the bearings during the installation process, sadly they used some kind of soft peice of tubing that didn't help. Because the current version offers more bearings seperated with some type of spacer which will not help if over tightened during the install process either. One serious problem surfaced because the bearing area was increased to allow room for the extra bearing and spacer, but also reduced the hub area that was needed to support the bearing race shaft and the hub. Although difficult to explain, the following result will hopefully make sense. When I pressed [by hand only] the two sides of a new clutch together, the center bearing race broke loose from the hub. During a later rebuild on one of the current versions the hub snapped off during the process of pressing on the new hardened bearing sleeve. After 2 problems in a row, I took a closer look and the reason the center was breaking from the hub is because of the deeper bearing pockets. There is only approx. 1/8" of metal connecting the bearing ramp and hub. I will attach a picture to show the contact area.
The next problem concerns the change in the pulley on the hub. In the past the pulley was part of the actual hub, however it is now a seperate part and attached via 2 roll pins, it is important to note the roll pins only extend into the holes in the hub a very small amount, and during testing the pulley worked loose and enlogated the small holes. I haven't measured the depth of the holes, but I would gess less than 1/8" [.125"]. The only problem with this system is when the pulley loosens, it spins on the hub, and the motorbike stops its forward motion.
As far as you cutting the inner drum, don't be real sure the bearing ramp, center hole, bearings, and inner hub are in correct alignment. On some of the hubs I just finished I found several where the bearing surface wasn't parallel, so I advise you to use a dial indicater on the bearing surface for alingment prior to cutting the hub.
Merry Christmas,