Wheel Nuts
Posted: Wed Oct 20, 2004 11:15 am
Perhaps I’m the only one who didn’t know this but……
Tired of rounding off the corners of new wheel nuts I decided to look into why they were a loose fit in a 3/8 inch BSW socket.
By measuring the distance across the flats of an old and new wheel nut and comparing it with thread form documents I found out the following:
The wheel studs on the Moggie are 3/8 inch UNF. Presumably Morris used UNF because it is a finer thread that BSW and therefore safer for wheel nuts. But, Morris have increased the width of the 3/8 UNF nut by .0225 inch to a total width of .710 inches to enable it to fit a 3/8 BSW socket. Thereby producing a non standard nut. Presumably they did this because this size was already in use on the car.
However, the new 3/8 UNF wheel nuts I have bought from several trade stands use the proper nut width of .6875 inches, which fits loosely into a 3/8 BSW socket and thereby spins when undoing a nut that has been tightened, perhaps over generously. The proper socket for a new wheel nut is 11/16 AF
So at present I need to use two sockets (3/8 BSW and 11/16 AF) to undo my wheel nuts. I guess the solution is to either use all new nuts, or try to get some old wheel nuts. I prefer the idea of using old nuts, to reduce the number of sockets I need to carry, but so far I have drawn a blank on where to get them. Does anybody have any idea if they are still available?
Ta!
Tired of rounding off the corners of new wheel nuts I decided to look into why they were a loose fit in a 3/8 inch BSW socket.
By measuring the distance across the flats of an old and new wheel nut and comparing it with thread form documents I found out the following:
The wheel studs on the Moggie are 3/8 inch UNF. Presumably Morris used UNF because it is a finer thread that BSW and therefore safer for wheel nuts. But, Morris have increased the width of the 3/8 UNF nut by .0225 inch to a total width of .710 inches to enable it to fit a 3/8 BSW socket. Thereby producing a non standard nut. Presumably they did this because this size was already in use on the car.
However, the new 3/8 UNF wheel nuts I have bought from several trade stands use the proper nut width of .6875 inches, which fits loosely into a 3/8 BSW socket and thereby spins when undoing a nut that has been tightened, perhaps over generously. The proper socket for a new wheel nut is 11/16 AF
So at present I need to use two sockets (3/8 BSW and 11/16 AF) to undo my wheel nuts. I guess the solution is to either use all new nuts, or try to get some old wheel nuts. I prefer the idea of using old nuts, to reduce the number of sockets I need to carry, but so far I have drawn a blank on where to get them. Does anybody have any idea if they are still available?
Ta!
