MTFCA Forum

What is the functional or geometric difference between a LH and RH #60 front arm on the beehive style? The brass tag and hard oiler bolt head tab are two differences, but the geometry seems to have the perch hole, shackle hole, and arm spring end all in straight alignment. Unlike pancake style arms with various pitches built in, it looks to me that the beehive arms get all the pitch from the perches. If you thing about it, the spring, shackle, and perch hole are all in straight alignment, so it would make sense that the arm geometry would be that way. However, I've seen on the forum where people said that you must use a left and right. So, functionally why (other than the tag and bolt direction)?

The Hassler instructions state to be sure the name plates face front, to identify L and R.

Without comparing each, there may indeed be casting features that are different, like the rebound peg to be sure it centers. And of course the oilers out front for ease, and the bolt locking edge for the larger oiler head head pivot bolt.

Thanks, Dan. I had thought of the rebound peg, but at least on the ones I have, they don’t appear to be handed either. It’s pretty common for the perch bolt holes to get really worn out and for the arms to get very bent out of shape. I have several arms with no to very little hole wear and I can see the holes haven’t been rebuilt, and I cannot tell a difference between RH and LH other than the bolt tab and brass tag. I guess it’s possible that they are in fact bent such that they are now symmetrical but started life asymmetrical. Another theory is that the arms are geometrically the same, and the instructions are merely making sure you put the hard oilers on the front side. It would seem like a poor design from a manufacturing and parts inventory perspective to not make them fully universal side to side, though. That makes me lean toward some geometric thing I’m not picking up on.

No more wisdom out there? I read through the patents and didn’t see anything that would drive being handed, but that doesn’t mean much.