Originally Posted by
southpawboston
My only experience has been with AW hubs. L and B would refer to 1st and 2nd, respectively, right? then N and H for 3rd and 4th? It sounds like either the pawls are worn or the clutch doesn't stay engaged. It could be that the clutch spring is weak. However, I would suspect a weak spring would be problematic in H, but not in L or B.
As for the trigger, aren't those pawls known to wear down and lose their ability to stay in a gear? I have an old 4-speed SA trigger that I'm using on an AW 3-speed, and it holds B very tenuously. It's never popped out on its own, but I barely have to touch it to get it jump out.
The older 3-sp triggers are marked L (low), N (normal) and H (high) which makes a lot of sense since N is the 1:1 ratio. When you add a 4th gear it's a super-low, so they called it B (bottom). The early triggers worked for either 3 or 4 speeds, and any 4 speed trigger will shift any 3 speed hub (except ASC).
Using numbers for the gears makes a little less sense, but of course it's not hard to figure it out.
Yes, the triggers are known for slipping out of the bottom gear. The cause of this can be worn trigger parts and/or weak trigger spring, but I have a strong suspicion that hub problems can contribute to the problem, and perhaps even cause the problem to begin with. I'm not sure; that's why I mention it.
Anyway, my hub overhaul reveals a misshapen "low gear key" which is a tiny steel cylinder with a hold drilled through it sideways. Now I have to find a new one of those.