Morris Minor Owners Club

Hi, I've got a 1966 moggy - a 'new' one buy morris standards I guess!

I remember reading somewhere that the weak spot in the half shafts is where there's apparently a 'step' down to the cut splined bit in the box end. Mine don't have a 'step' here - the spline is just cut straight into the shaft. Is this right?

Also, is it worth fitting hardened shafts as a pre-emtive fix - rather than replacing standard ones when/if they break?

Also, how weak are standard shafts? There seems to be a lot of conflicting opinion about this..

I know thats a fair few questions for one post but I'm new to minors so thats my excuse!!

thanks
jon

Well my 1966 didn't have any problems with standard half shafts in the last 15 years of me driving it and the 20 years before that of my parents before me. On a standard 1098 engine with 48bhp I cant see HOW it's possible to break them - i did my fair share of trying in the first few years of my licence . Ive recently upgraded to a 1275 engine and put toughened ones in that are apparently good for 70bhp or so. After that it depends on how hard you drive.

There was nothing at all wrong with the original half shafts, it is
just that many of them have done many many thousands of miles
and all mechanical things eventually wear out!! The ridge you mention
would be found on the actual splines and is a consequence of the
splines rubbing on the planet wheel in to which it fits....again normal
wear and tear. The same half shafts were used in the Riley 1.5 cars
and were quite capable of handling the increased power AT THE TIME.
If you happen to see the pronounced ridges on the splines then you
have been warned, and NEVER swop them over to the other side!

I did break one many years ago - but I was autotesting the car at the time - with massive rear axle tramp !

It's worth checking your halfshafts for visual wear as even a mildly modified 948 can break worn shafts. I believe a standard shaft can cope with 70bhp and a hardened one 100bhp.
Eliminating axle tramp will go a long way towards preserving halfshafts as too will running standard width tyres. It is the torque of the engine or more specifically the resistance created by the grip on the road (tractive effort) that twists the shafts and causes failure.
I raised the comment some time ago about the right angle cut on the spile of the halfshafts. I suggested it was a stress raiser and should have had an additional 45° face or radiused cut.

Peetee wrote:It's worth checking your halfshafts for visual wear as even a mildly modified 948 can break worn shafts. I believe a standard shaft can cope with 70bhp and a hardened one 100bhp.

that's interesting because as I understand it from others on this site the hardened ones will cope up to 70 or so and not 100. But I guess they would cope with whatever bhp if you drove with a light foot. Not bmcecosse by the sounds of it

I used to break half shafts with great regularity on my MGB engined minor (highly tuned - reputedly 130 bhp - before dynos were the norm) which had a Riley 1.5 axle. I always took a spare diff and shafts with me when I ventured any great distance - ie car meets in south of England. When I ran out of Riley parts, and just before I changed axle to Capri 3 litre, I used minor shafts and never broke one!! I think this is because they probably had a bit more reserve of strength left in them compared to the riley which obviously had more power and torque and therefore fatiqued them more. If you are seriously worried, then I suggest upgrading to Ford - it's not hard or expensive.
Incidentally, my wife's minor with mildly tuned 1100 totally exploded a riley diff resulting in a ruined axle casing, so it's really down to luck.

Pete

so it's really down to luck

yes! I've abused a lot of Minors and never broken a halfshaft!

nor me

I had a less than six years old Traveller which I used to tow a large
boat full of diving gear to Scotland from London and back and a
shaft snapped three weeks later!

I've never broken one either, but if you need more poer handling capacity then as Plastic_Orange says, upgrade to a Ford unit. The Mk2 Escort one I have has RS2000 halfshafts and can apparently handle 170 BHP! So I have plenty in reserve.

As an aside, my grandad bought a brand new Ford Anglia and snapped a halfshaft almost straight away! After that, he vowed never to have a new car again. He never had a Ford again either!

Just seen this post. My 1275 Traveller has around 75 bhp and whilst I don't do racing starts, it is best part of 30bhp more than a standard 1098. I have radius arms fitted, so no axle tramp and the Quaife diff gives me better traction, so less tendency to slip and then grip. It occurred to me that the Riley 1.5 had around 68bhp and possibly more torque than my engine. Was the Riley halfshaft made from anything stronger than a Minor halfshaft?

Thanks for highlighting this thread Blaketon, I like to see all those names from the distant past, apart from those that are dead no one says Goodbye, they just walk away !

Les
I do not intend to walk away without a fight.

As far as I can ascertain the Riley 1.5 and the Minor half-shafts are the same Pt No: ATA7057.
What I have done to increase the longevity of the half-shafts was to purchase a pair of NOS half-shafts get them heat treated and they are now capable of transmitting 178BHP.
The 1380cc engine after original build was giving out 145bhp.
I have had no problems with half-shaft failure and that is after many many full power standing starts.
I would not expect the same power transmission capability/service life with a pair of S/H half-shafts.

My 1969 Traveller's half shaft broke on the way home from work in 1999. I fitted a second hand replacement. It clunks a little but it is still running.

Willie wrote: ↑Fri Sep 16, 2005 5:54 pm .... The ridge you mention
would be found on the actual splines and is a consequence of the
splines rubbing on the planet wheel in to which it fits....again normal
wear and tear.

Years ago an "old-school" motor engineer with years of pre- and post-war experience showed me a selection of used half shafts. He pointed out that the wear ridge caused by years of tiny movement between the shaft splines and the diff was not the cause of breakages, and was merely superficial. A far more ominous sign was the beginning of a twist which could be observed by looking end-on, indicating fundamental weakness inside the shaft.

The twist is what breaks the half-shaft.
That is why you should always re-fit the half-shaft to the side of the axle it was taken from. Half-shafts do not like being reverse twisted (twisted back again).
Basically - heat treating the half-shaft normalises (brings back to normal) the way the molecules in the metal lie so reducing any built in or induced stress factor.
That is why I had my NOS ex factory half-shafts professionally heat treated so that they can now handle around three times the original torque whilst still being produced/made from the original factory metal specification.

Hi,
On my former 2 door Abby I fitted EN24 High Tensile Steel half shafts because I was told the originals wouldn't cope with the 1275 engine I'd 'upgraded' her to.
Guess what, they broke (sheered off) pulling away at some traffic lights near where I lived.
I then, initially out of necessity, refitted my original half shafts and they never gave me any trouble again......
I'd stick with the originals unless you know they are in a bad way, rather than waste good money like I did.
That said, a better option might have been Phil's:

The twist is what breaks the half-shaft.
That is why you should always re-fit the half-shaft to the side of the axle it was taken from. Half-shafts do not like being reverse twisted (twisted back again).
Basically - heat treating the half-shaft normalises (brings back to normal) the way the molecules in the metal lie so reducing any built in or induced stress factor.
That is why I had my NOS ex factory half-shafts professionally heat treated so that they can now handle around three times the original torque whilst still being produced/made from the original factory metal specification.

I've never heard of this method, where did you go to get them heat treated?
Best wishes,
Mike.

The heat treatment of half-shafts is a common way of increasing their strength.
I had the half-shafts treated at a specialist firm in Northampton. That was many years (at least 40) ago and I do not have a contact address and they may not even be trading now. I do have a spare set if required though.

philthehill wrote: ↑Sat Jan 10, 2026 10:36 pm The heat treatment of half-shafts is a common way of increasing their strength.
I had the half-shafts treated at a specialist firm in Northampton. That was many years (at least 40) ago and I do not have a contact address and they may not even be trading now. I do have a spare set if required though.

Perhaps it was Home - Heat Treatments https://share.google/8ZzHTPy8jdf8gCz5x