There seems to be both a lack of detailed information and a disagreement of the information available on rear axle housings. I don't find them in the Rodda books at all. The dealer catalogues that offer used housings list them as 1916-1925. The encyclopedia shows 1915-1919 and 1919-1925. The housing changes shown for 1920-1925 are not physical, just part numbers. Apparently the change of tube size was in 1919, with the diameter increasing by about .05". This means 1919 and later end caps are a loose "fit". That includes the current reproductions.
That brings me to the question. What's the best way to adapt the "too big" caps to fit properly on the earlier tubes? I have a couple of ideas, but maybe somebody else has a better one.
Steve I have some NOS (slightly rusty) original correct size caps for the earlier rear-ends, they fit tight
I have some new accessory caps with a modern seal for early housings also.
Steve,look on page 22 of tinkerin tips vol. 2. It tells you how to tighten up a bearing cone. I did this on my 14 years ago and it is still good. If it works on that it should work on an axle housing.
Just a thought
If I remember correctly there are very good photos in Les Henry's book of the different year rear ends.
This may not help with change over and what caps fit correctly however but does show the changes and help date them.
Part # 2510N Fits 09-17
Don't forget, they lowered the oil fill plug sometime in 1918 or 1919, not to mention the 15-16 style backing plates.