[Healeys] Whitworth vs UNC

[Curtis Arndt]

The bolt is 5/16" BSW!   Don't let anyone tell you different.

Even my 45K original mile '60 Bugeye has its original  5/16" BSW bolt in
the generator front plate.  The problem arises since a 5/16" UNC bolt has
the same tpi (threads per inch) as the 5/16" BSW bolt.  The issue is that
UNC has a thread pitch angle of 60° and Whitworth by definition is 55°.
The wrong bolt will never torque properly and will eventually wear the
aluminum generator front plate.

Cheers,

Curt

On Mon, Dec 21, 2020 at 3:53 PM Roger Grace <roggrace at telus.net> wrote:

> My understanding is that they are close but not interchangeable ?
> Thread angles are slightly different.
>
> For AH generator adjusting link is this 5/16 W or 5/16 UNC ?
>
> At back of my mind think they should be Whitworth -  think you told me
> that is why they come loose if you use UNC ?
>
> Finding it difficult to identify one from the other.
> Any tips to do this welcome.
> Have a definite W bolt and comparing to UNC can only see slight rounding
> of UNC ?
>
> Moss sent me a UNC bolt for this link - well that is what they called it ?
>
> Would appreciate your expert input.
>
> Regards,
> Roger Grace
>
>
>
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