Howard, that illustrates my thinking. You can cut a slot in a shaft for a square section key with a rotary cutter or an end mill, but you would only cut a slot for a Woodruff key with a rotary cutter of the correct diameter (I'm sure you could cut it to the correct radius by other means, but not efficiently). Given that the benefit of a Woodruff key is that it will self align parallel to the hub axis (I.e. the leading edge stands up more from the taper surface than the the inboard edge) and cannot work its way out along the keyway, which is blind at both ends, why would anybody design such a skinny key requiring a potentially unstable tool to cut the slot in the shaft? A rotary cutter 3/16" thick with a diameter of 2 3/4" would be very tall and thin for stability when cutting. It would be interesting to see a photo of the keyway in the shaft from Tod' s car.
17-03-2020, 03:17 PM (This post was last modified: 17-03-2020, 03:23 PM by Peter Sweeney.)
The Heavy axle does have a long thin key. These photos are of a duff shaft and the key removed from it. This is from the big 7 but my special with the heavy axle is the same type of slot and key. I had the same happen in the special and the key had become a grainy black powder. I made new ones from the edges of a 1/42 thick steel disk in memory 4" which are still in both cars.
Can't seem to put photos on!! will try again
Oh dear.
I understood the long tapers were more or less immune to this scourge of the earlier.
Could start a rogues gallery of axle ends. I have seen many with huge portions broken out, dunno if this is most common failure or just that cars remain mobile so are acquired in this state and so observed. With fluid, cracks can often be detected but if normal to follow the key and not progress across the axle hopefully not serious.
On another make with a taper it is common to slide the slack straight key in after assembly so avoiding risk of riding on the key. So at least some cars do not involve the key for drive.
That half shaft has destructed because the nut has been loose.
The nut should be tightened to at least 150 foot pounds. I use a lot more. It is not really necessary to fit a split pin but it is necessary to check the tightness regularly, say monthly for a high mileage car.
Use original Austin Motor Company half shaft nuts, they are far superior material than modern repros.
If you feel that you have to fit a split pin tighten the nut as above and then tighten it 'til it lines up.
Never, ever turn the nut back to line up split pin holes.
I made up 2 new keys today from 3/16" Ground Stock flat bar. Fortunately the key way in both the shaft and hub were in good condition. As best as I could measure the root radius machined in the shaft is 1.5" radius x 0.250" deep. I made the length 2 3/4". The key way in the hub is 1/16" therefore I made the key height 5/16" less 0.010" to make sure the key does not hold the hub off the shaft when tightened.
Tod
