Rear axle failure

I have taken apart the rear wheel assembly from a 1972 and found the threads on the axle are deformed.

I searched the forum posts and read that failure on the axle is typically a break at the end of the threaded portion.

I wouldn't run this axle on a road bike any more but has anyone tried to clean up the threads using a 9/16-20 die? I would guess that the original threads are rolled rather than cut to lessen the stress at the end of the threads.

I think this happen when not following the proper tightening sequence.
Once everything is adjusted, chain, alighnment etc, the dummy axel must be snugged first, then the main axel.

No doubt everyone will disagree with me but:

There is no reason to over stress the threads to the point of stretching deformity because it serves no purpose in terms of the actual functioning of the axel.

The only reason to tighten the axel is so it does not find a way to rotate out of the left side dummy axel.

When I removed my speedometer drive unit from the rear wheel some 20 years ago, I found I could not fully tighten the axel because that small amount of spacer washer was now gone.

Instead of simply putting a thick washer in place of the speedo unit width, which I now have, I found that when I tightened the axel the right side swingarm would move in and the wheel would bind.

So, ok go ahead and laugh but I was younger then, I "solved" this problem by just barely tightening the axel with some locktite on the threads. It never loosened and I rode for without incident for the next 15 years that way.

I guess my point is that people may well overtighten their axels and stretch the threads out of alignment, when really all that is necessary is tighten enough so it cannot unthread, and that takes very little tightening.

What has puzzled me, for quite some decades, is that if you buy a new axle for a BSA say, which uses the same quick removable wheel idea, the axles are obviously hardened, and go 'ting' if you tap them with anything metal. Never a problem.

Commando axles seem to be softer. I've replaced several where the threads seem to be on the point of failing, as received. (And sighted several bent front axles)

The short stub axle doesn't seem to be a problem.
Did someone skimp on the material selection, or the heat treatment ??

Step on the brake, nip up DS dummy axle then its pretty vital to get enough clamp force on the long axle so it don't slip backwards away from the adjuster stop d/t the chain pull and of course that's also enough to keep from coming loose w/o any glue. Above axle looks like someone might of tried to relieve the sharp valleys as the axles I've installed and broken all ended with same thread cut right up to the full dia. section. When they break the short end left in the dummmy axle has about 1/3-1/2 turn of a thread remaining on it.

1up3doun has the right approach here, I believe. 25 lbs is enough torque. As the wheel hub heats up--and the other parts that are shis-ka bobbed on the axle---it expands. Too tight and something has to go pop. weakest link is the stress riser threaded axle. Why it has a tendency to fracture at the last thread ????????. May be due to it flexing there more. Personally---never had any break---yet.