How much end play should the armature have

I don’t know the specification but end play must be limited to keep the brushes on the commutator at all axial positions. Based on generators I have worked on I would guess up to 0.030” would acceptable.

I have successfully used a finger spring washer in the brush cap end bearing. McMaster-Carr p/n 9717k65 takes up the endplay, and gently preloads the armature assembly without needing shims. jb

When I rebuild a model T generator I install new sealed bearings and I locktight the front bearing in the end bell with the bearing inserted all the way into the bore. This eliminates any end play and allows the rear bearing to travel in the rear endbell to adjust for thermal expansion and contraction.

James A Bartsch
I attempted to look up the spring washer McMaster Carr p/n 9717k65 you mentioned but found nothing under that number. Is it possible that there is a different number? Thx

It is a valid McMaster-Carr number. I couldn't find it either tho.
Went a different route and bingo. I think. :-)
Try this page
https://www.mcmaster.com/#catalog/123/1298/=1aastcb
Does this work? Scroll down just a little bit.
:-)

Joseph, sorry I was too brief, Duey has it, when I enter the p/n in the MMC page Duey referenced, the part info and a pic comes up. These are sold in a 10 pack for about $11. I wish our usual vendors carried these in addition to all the excellent generator parts they already stock. best to all, jb