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MG Midget and Sprite Technical - Metallurgy - Broken Halfshaft

Here's the broken 'Peter May' halfshaft, which I mentioned in the rear wheel bearing thread.

This is the flange end.

Dave O'Neill 2

This is the shaft, itself.

Unfortunately, it has gone a little rusty during its 20+ years in storage!

Dave O'Neill 2


Not having seen the shaft before that is where I would have guessed it would have failed due to the abrupt change in section. What was the set-up of the car, if wide tyres, racing etc then maybe a double bearing hub would be appropriate to hand some of the loads off the the axle casing.
David Billington


It was on a race midget, but only MGOC spec, so not huge power and only 155 road tyres.

It was a two-piece shaft - now a 3-piece - so the shaft itself doesn't have a change of section at the break, although it obviously does meet the flange there.

The bearing did have excess play.
Dave O'Neill 2

20 + years its been in storage. What did peter may do to remedie your situation

Id imagine in 20 years changes have been made to avoid this break...i domt know, but im not in favor of speaking ill of a company 20+ years after the fact...3 months, 6 months a year okay, but 20+ years is ALOT of water passing under the bridge

What is it you wish to accomplish with this posting

1 Paper

Prop, I'm not speaking ill of anybody.

On another thread about wheel bearings, it was said that the halfshaft would bend if there was a lot of movement in the bearing.

As stated above, there was excess play in the bearing, which is why the shaft broke IMHO.

The moral of the story - check your wheel bearings regularly.
Dave O'Neill 2

And make sure you use the correct sized hub gasket to avoid movement there too. ;-)

Great failure there Dave! :-D

Malcolm Le Chevalier

Thank you dave for the clariffication id hoped this wasnt what i had imgined it to be, you have always been a stand up guy, sorry i allowed the temptation to say something

Former comment withdrawn...(at least in spirit ):

1 Paper

My Peter May shaft broke on the diff-side like the standard halfshaft before it...
The PM-shaft is the one on the right.

A de Best

Is it always the left hand one which breaks?

Nice bathroom, by the way ;o)
Dave O'Neill 2

Dave, to be honest I cant remember it always being the left one that broke...
If so good observation!

That bathroom is no longer since this spring... RIP
Thousands of Euro's later(not spending it on the midget..) we have a new and roomier one.

When I think what I could have done with that budget for the midget... :)
A de Best

I appear to have been summoned.

Dave, that halfshaft has failed from fretting between the flange and the shaft. All those little striations around the outer edge of the shaft are the giveaway.

The loose wheel bearing may be what finished it off, but the sharp edge on the flange is what started it. If I were running a similar two-piece halfshaft I would be tempted to use a touch of retaining compound between the flange and shaft, and maybe reduce the shaft diameter for a few inches before it meets the flange.

Thanks Growler.

Funnily enough, I've never broken the splined end on a race car. My starts tended to be quite controlled, not side-stepping the clutch - like Arie!

I did once suffer a twisted third motion shaft, although that may have been down to someone else 'abusing' my car, as the splines in the clutch plate failed about the same time.
Dave O'Neill 2

If you haven't busted a halshaft your to carefull!
Drive like you stole it!!! ;)
A de Best

If you haven't busted a halfshaft you probably have a shot peening setup in your workshop? ;-)


That looks just like the break I had on my first car, a 1964 MKI. It was back in 1975, and as luck would have it, that axle was available at almost any auto parts store. It set me back 40 bucks.....
Paul W 1976 1500

Arie, is that bigger bathroom to make room for more busted halfshafts??
Paul Walbran

This thread was discussed between 15/08/2017 and 19/09/2017

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