312TD Sheared wheel studs - WHY?!!

[antiquedealer]

Hi out there. I have either a recurring problem or just coincidence. 1996 312TD 14 foot floor Luton. Recently I've had 2 wheel studs shear on a rear wheel, approx. 700 miles after rear brake service, etc. Mechanic (known for several years, services our own cars and classic too without problem) is cetain he tightened nuts. Had old stud ends removed, used spare wheel until I got a replacement road wheel. Emptied van, changed wheels. The studs were tightened manually, believe yoiu me! No air supply so I had to use a spider. Reloaded van. Drove four miles to Services to check tightness and found one replacement stud had already sheared. WHY?!! Thanks for reading

 

[pascal]

I don't fully understand your question.

Are you saying that the treads were sheared on the replacement nut after 4 miles.

Could the problem be with the female treads on the hub?

 

[antiquedealer]

When 2 nuts sheared, guy who effected repairs (not my mechanic) removed the sheared-off ends and supplied 2 replacement wheel nuts.
When I swapped the wheels last weekend I used the same 5 wheel nuts. Yes, it was one of those nuts that had sheared after 4 miles. They had all been tightened as much as I could using a spider and tugging on each in turn!
As you suggest, it is always a possibility that the female thread could be the problem but if that was the case, how come the nut can be tightened up? Surely it would fail to tighten completely?