Oh dear

[Steve kay]

   
One of Shropshire's Chummy owners has just sent me this picture of today's discovery. It is a job to know what to say.

[Ian McGowan]

Only one thing to follow your "Oh dear!" Steve and that is new halfshaft needed.
The only good news is that whilst dismantling the rear axle to replace the halfshaft, you may as well go the whole hog and tackle the leak of lubricant visible in the photo.

[Alan]

It’s not the end of the world. Remember the 1978 record attempt was really about how quickly we could learn to change a half shaft. I think the winner was around 20 minutes. All the bits are available and in the general scheme of things it’s not a difficult job. Keep smiling.

[Hugh Barnes]

As Ian says, resolve the excess diff oil that is clearly evident. Jamie's modern oil seals from the Workshop are a perfect fit but, more importantly, check how much oil is in the diff. A mere 250ml does the job. I've just dealt with mine and drained 600ml out of the diff, which accounted for the incontinence...

[Steve kay]

This is neither of my back axles, phew. It is an early axle, with 6" brakes and early bearings etc, all too often not that easy to come by. By remarkable good luck Mr Cochrane has just got some of these in stock.

[Colin Bromley]

It is my axle, Steve understands how to put images on here, I do not... The car developed a vibration a few weeks ago, which came and went, today it was so bad the car was almost undrivable, various telephone calls made, and this was what was discovered. Mr Cochrane has been contacted and is supplying all the necessary components to repair the little blighter.

[Bob Culver]

I guess the thing to say is "Not untypical". I dont know if the original Austin axles commonly fail like this but the very hard through hardened Regent ones seem prone. It is remarkable that the half moon seems to  steer the cracks from progressing traversely.
The diff on my car was changed but at 110,000 miles the original axles are intact with small cracks only detectable with fluid. Never lapped and not regularly retightened. 
I have a collection of such axles from derelict cars and diffs. I dont know what proportion fail transversely but as the cars are rendered immobile less likely to come across.
If selling the car, relieve the centre of the taper slightly and reassemble very tight!

[circeonya@hotmail.com]

In my youth I was strapped for cash and one of my axles was in similar condition, but the piece beside the key was clean, so a new key and carefully putting piece in place and reassembly was the drill with that car. The key would only break when I was hooning.. BTW no one mentioned you can push the half shaft in and that will lock the diff action to get you home.

[Bob Culver]

I have recounted before but in the early 60s when my car was everyday transport a somewhat more youthful apprentice mechanic a few doors away was running a Ruby. The cars in use were rare by then so we naturally new each other. He ventured way out of town and twigged things were amiss in the hub. He called into my fathers house for tools. The axle was as the photo or worse. He had trouble balancing the key to put the hub on. My fathere although a plumber was meticulous in matters mechanical and was aghast! 
The owner had previously experienced a broken axle.It flicked itself through and he could not fathom why the car suddenly steered under throttle. I guess the reason would tax more then an apprentice.