Rear Axle Adjusting Screws

[MikeW]

My 1921F restoration project bike came with one long and one short rear axle adjusting screw (photo numbers 713 and 714 in the 1923 Spare Parts Directory).

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They are the top two screws in the photo below. (The bottom two are modern long screw reproductions.)

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The 1923 basket case that sits in a corner of the shed also has one long and one short adjusting screw. In this case the long screw seems to be fitted with the "Rear Axle Adjusting Screw Collar", Photo 715 in the Spare Parts Directory. (The area shows the signs of heat and penetrating oil as I've tried to get the adjusting screw out without shearing it off. It's half-way there.)

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My questions are "Why was the long screw introduced? What is its purpose?" As the rear axle adjusting clip is reversible, it seems to me that the short screw can be used for the full length of the rear axle's travel in the slot in the rear frame. To illustrate:

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In the left hand photo the short adjusting screw has reached the end of its adjustment. In the right hand photo the adjusting screw has been backed out, the adjusting clip has been turned 180 degrees and the screw has plenty more thread left to do its job. Why do we need the long screw? Am I missing something?

Mike

[dukekleman]

Mike,
I do not know.
However on other models and other brands this was done for ease of access to the adjusters with the wrenches/tooling that was available in the tool kits.

Duke

[Steve Slocombe]

Dear Mike, the long rear axle adjuster screw goes on the sidecar side, as otherwise it is hard to reach with the sidecar attached.

[MikeW]

Thank you Duke and Steve. The long adjuster screw on my 1921F was indeed fitted to the left hand side - the sidecar side in this part of the world - and, from the many photos I have peered at, most of the long screws (when they can be seen at all) have been on the sidecar side of the bikes as in this U.S. example. This also illustrates the purpose of the adjusting screw collar, which holds the locknut out from the axle where it can be more easily accessed.

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And it looks like a short screw on the left-hand side of the H-D Museum's 21JD below?

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Again, your input is much appreciated.

Mike