Half Shaft

[Ruairidh Dunford]

Were they newly manufactured like this Steve or are they old ones that have been turned down and then added to? I am trying to get my head around why they have been constructed the way they have.

[Charles P]

The odd thing is that it takes a high degree of practical machining ability to do that to a half shaft.
I'd expect that type of craft skill to go with some basic understanding of the application, and the judgement that it was a really crap idea

Charles

[Alan]

The If my memory serves me well they were new tapers grafted in to used gear ends. Probably to save the cost of cutting the gears, and ends of broken half shafts are in plentiful supply. Not a bad idea if done properly- there are plenty of offset axles like this on racing sevens that have a few more than 11hp to transmit.

[Ruairidh Dunford]

You have confirmed my thoughts Alan and, as you said, there are plenty of examples of it working when done properly.

There appears to be an innocent party selling what they think are good half shafts that were perhaps discarded, but not thrown away.

[A G Wood]

I concur with you two gentlemen. I have seen it done by the hot rod guys and the stock car fraternity when they shorten a half shaft to avoid the hassle of re-splining it after shortening. Minimal spigot both in diameter and length of, vee'd out, set up between centres, tacked up, multi-pass welded with the appropriate electrodes and machined. Sounds rough as, and not to my taste, but it works fine even with a big V8 on the other end.

[Charles P]

I concur with you two gentlemen. I have seen it done by the hot rod guys and the stock car fraternity when they shorten a half shaft to avoid the hassle of re-splining it after shortening. Minimal spigot both in diameter and length of, vee'd out, set up between centres, tacked up, multi-pass welded with the appropriate electrodes and machined. Sounds rough as, and not to my taste, but it works fine even with a big V8 on the other end.

Agreed. 
I guess that that you could use the new taper part, shorten it slightly and recut another knackered half shaft and do it property.
All it needs is a lathe and a tig. I did much the same to replace the motor on a Bridgeport milling machine.

Charles

[Steve Jones]

The half shafts were produced as above by utilising the 'gear' half of an original shaft mated to a new 'taper' half. The spigot and socket joint was a tight fit and the only fixing of the two was a weld around the external edge of the joint that was then turned to the original half shaft diameter. No friction welding, no pins etc. etc. It didn't work!! If the shafts that now appear to be on the market are from the same batch as mine from 30 years ago (and the circumstances suggest they might well be) then as Ruairidh says, an innocent party is selling them without realising. Hugh, the original poster, obviously knows where he bought his half shaft. Perhaps he should draw his supplier's attention to this thread to prevent further problems.

Steve

[Reckless Rat]

The failure in the "cut & shut" half shaft is down to poor weld penetration between the two halves, not the concept itself. I'm sure this can be recovered, as Charles said by creating a 'V' between the two machined ends and then building up with weld. Personally I would belt & brace it by two pins through both halves, at 90° to each other, both welded in place, with the repair machined back down to diameter.

[Chris KC]

I'm no welder Reckless but I'm inclined to agree - they should be possible to re-work if they indeed exist as a batch somewhere.

[Charles P]

The way the spigot is machined precludes recovery using those two pieces. You'd need full penetration in both halves and that's not possible with that join. The outer, tapered part is too thin. 

Just my opinion.