Morris Minor Owners Club

Well done.
Here is the link to the classic Mini open ended wheel nuts I am now using.
https://www.ebay.co.uk/itm/304564911790 ... R87Rv6r0ZQ
From the dimensions you have given you should have had enough thread for the capped nut to hold the wheel without bottoming out.

You do not need to utilise all of the thread on the studs to secure the wheel just threads of at least twice as long as the stud diameter.

So I suggest two possible theory's for the wheel loss:-

1. The wheel nuts were not tightened to the 38lbf ft torque as specified in the Minor workshop manual.

2. The wheel nuts were over tightened which lead to the studs snapping.

What ever the cause you survived the incident and that is the most important thing.

As an aside - I would check that the wheel centre inner face sits square and fully on the brake drum outer face without any fouling of the raised face of the half-shaft.
Phil

Thanks Phil. I will recheck measurements. I have just rung JBW and they say the capped nuts should be fine on long studs.

I am 99% certain that the reason for the wheel loss and broken studs is that the nuts were not tightened by me after adjusting the rear brakes. I think the studs broke due to the hammer action of the wheel vibrating against the drum and nut because it was not clamped down properly.

I can't rule out that the nuts have been over- tightened in the past, and this seed of doubt is what made me replace all the studs, not just the broken studs.

I've had the alloys, capped nuts and standard length studs since 2014, in which time they've done about 30,000 miles without issue.

It brings home that something as simple as studs and wheel nuts are safety critical- get it wrong and it can be nasty.

Had a run in it tonight, then checked the wheel nuts. All ok.
I've done them up to 38ftlb, though that does not seem tight enough, I can easily get another nip on them.