Hi guys,
At the recent huge vintage motorcycle swap meet in Davenport, Iowa, I stumbled on a bolt-on 42T sprocket that I thought would work for my '57 A7. I did not have the old sprocket or a photo of it with me at the time. New to the A7, and ignorant of other models with bolt-on sprockets, I snapped up the subject sprocket at a cheap price. Today, I went to see how it would go together with my full-width aluminum hub, I was surprised, and p**sed (at myself, not at the seller), that the bolt circle on the "new" sprocket is smaller than the bolt circle on the hub. I was also surprised when I counted the teeth on the old sprocket to find 41 and not 42. I soon realized that some P.O. had adapted a sprocket ring to the original (I suppose) sprocket disc. That explains the difference in the number of teeth, but not the difference in the bolt circle. Does anyone know what bike the sprocket with the smaller bolt circle would fit on? Except for the bolt circle, the new sprocket fits my hub just fine. If I knew what it came off of I could properly advertise it on eBay or, maybe, buy a hub that works with it, since the hub has its own problems.
Regarding the hub. Some previous owner (probably the same guy) drilled two of the stud threads out for 1/2 bolts. One other hole is completely messed up with something stuck in it (maybe JB Weld). The fourth hole appears to have a good 7/16-14 BSW thread, however, the bolt that was in it seems to be UNC (American) 7/16-14. Because there is a very limited selection of inserts for oversized holes and, also, because the studs that mount the sprockets are kind'a special, it would be great if I knew I could use 7/16-14 UNC inserts with 7/16-14 BSW studs. Of course, one way to know is to just by the BSW studs and test them in a UNC hole, but I'm impatient for the knowledge.
Thanks for any help you might have to offer.
Richard L.
Edit: I meant to attach these pictures. Also, allow me to be the first to make a joke about "No Hot Ashes". There, consider it made.