I've dusted down an old Caterham speedo that I had kicking about. Might put it to action.

Can anyone help me by identifying the function of the aperture at the top left of the picture?

Ta muchly!

Isn't that were you put the key in to wind it up?

i think it takes a small cable attachment to reset the trip meter????

Yeah, its for the trip reset, it has a small cable on it. One of those might take some finding!

Scott

Yep - looks like the standard smiths fitting so should be easier to find.

Thanks all!

Seems so obvious now... DOH!