Wheel Nuts

S

steveg1664

New Member
OK, I'm probably being an idiot here but can anyone please tell me what thread wheel nuts a 1972 P6 should have. The manual I have seems to suggest they should be 7/16th UNF which they're not. I wondered if they had been replaced with SD1 10mm but they haven't. Any ideas?
 
Thanks Ian, I tried checking this with what I thought was a 7/16th MG Midget lug nut which was too big. In the light of your reply I invested in a thread guage and found that I had used an MGB 1/2" nut in error and that I do have 7/16 studs fitted.

Steve
 
What's Whitworth ? Is it a thread size ?

Is the correct spanner size therefore 7/16 UNF ?

Metric and AF is so much easier to understand
 
hi dave,
the UNF is the diameter of the nut or bolt not the spanner size, F is for fine thread and UNC is coarse which are mainly used in to the engine. spanner size for the p6 wheel nuts is around 3/4 AF, can not remember precisely ?

ian
 
'Whitworth' is the name given to the Imperial measurement. 'British Standard Whitworth' (BSW) is one of the imperial unit based screw thread standards which use the same bolt heads and nut sizes.

'AF' is a North American 'American Fine' Standard for measurement, but not a thread standard. The American standard for threads is 'Unified Fine' (UNF).

I think I correct with these.
 
Christ guys! all I asked was what thread the studs should be. But if we're started on it-
Unified National Fine (UNF) or Course (UNC) are based on the diameter of the bolt/stud and the number of threads per inch but there is a direct relationship between this and the spanner size needed for said bolts.
AF is a spanner size which Mike correctly states stands for across flats. Both were developed in the USA for aviation use and came across the pond during WWII.
Whitworth sizes were quite common in the UK once upon a time but were replaced by UN/AF because these are easier to use and I am told have better thread characteristics especially for automated thread cutting.
I remember that my father was delighted when he bought a 1960 Ford Zodiac and found he could throw his oversized and clumsy Whit spanners in the back of the shed.
 
Mr Whitworth became a VERY rich man by standardising his own threads & negating the need for engineers cutting their own every time they needed one.
Learned that from one of good old Fred Dibnah's programmes.
 
Just a couple of points, UNC and UNF are both cut with the same angle as METRIC ie 60 degrees
WHITWORTH are cut at 55 degrees. The differences between UNF/UNC/metric lie in diameter,pitch, and pitch depth. The books to buy to find out more about this subject are the Zeus book(very cheap about £2 quid) or the machinist handbook(very expensive £30ish)
Cheers John
 
got all this in o grade metal work back in 1980's & and also all the info on ACME threads, bsp etc off course long since forgot!:D
 
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