mk1-forum.net

can someone let me know correct bolt size and head type that fixes the speedo to the plastic pod please?

Martin, I refer to them as 3/16 UNF but apparently they are not called that. The thread is the next size down from 1/4 UNF and there are lots of examples of it on a Mini, particularly a mk1. Examples : door catches, rear view mirror, window catches, speedo pod to bulkhead. I have an assortment of them if you need some.

If they are the next size down from 1/4 and fine thread they will be 10-32 (which you might call #10 UNF). However, I thought most the speedometer fasteners were BA threads. A #2BA tapped hole will typically accept a 10-32 screw but it will be tight.

Caution: Useless Information to Follow.
The small numbered fasteners in the UNF/UNC series below 1/4" use a sizing scheme that is based on diameter steps of 0.013". This is easiest to remember if you start with the obscure and seldom used #5 screw which is 0.125" (1/8") on its major diameter.
A #6 screw is .125+.013 = 0.138" diameter and a #4 is .125-.013 = .112" diameter
Therefore, a #10 is .125+((10-5) x .013) = .125+(5 x .013) = .125+.065 = .190" diameter.
Of course, complicating this, for proper fit, most fasteners are about 0.004 "undersized" so a #10 will really measure about .186" which is almost exactly the same as the 2BA thread I mentioned above.