Monday, 9 January 2012

Almost a red spot ammeter

Well, here is the first of the post-Christmas presents!

This is the kit of parts that I have, now that I have stripped a Lucas red spot ammeter that I bought on eBay from a member of the AOMCC, for a lot less than one can spend on such things.

It is a bit of an oddity. It seems genuine, it has a Lucas part number and is made of parts of approriate 'quality'. It is marked '1980', and I guess it was a replacement part for vehicles still using red spot ammeters. It is marked 'Lucas' on the dial, but it does not have a window in the back, like the earlier versions that would have graced Amelia's curves when she was new, and it has no facilities for an ignition lamp internally so it could not have functioned as the red spot ammeters were intended to do.

The plan is to replicate the parts used for the ignition lamp and to cut the window through the ammeter, so that we end up with a suitable white faced ammeter with the functionality that we need.

So, starting the work. Here is the back plane of the meter, with it's insulator. I've marked out the holes I need, and I've drilled a pilot hole in each. Then I have taken my piercing saw with it's V-table and carefully cut the shape we need for the ignition lamp aperture. I've cleaned the hole up with needle files.
Here is the back of the ammeter, the back plane and the insulator, all assembled and showing the aperture lined up. Not quite right yet.

Here's are the prototype parts for the ignition lamp. Following the style of the original ammeters, I have used a plastic card to replicate the tufnol insulator that is used to mount the lamp holder, just to get the shape, and the position of the lamp correct in relation to the aperture on the back of the meter.

The lamp holder is mounted on a small piece of 0.5 mm aluminium sheet, pop riveted to the insulator. There is a plastic insulator between the centre terminal of the bulb holder and the mounting bracket.

So for now, the lamp is in the correct place. We will reassemble and see if it looks OK from the front, when it is illuminated, then we will make some nicer parts.

Here it is, put back together with the ignition lamp off...

And here it is with the ignition lamp on! Isn't it exciting!


  1. Good gracious... I've just seen one of these sell for £205.00 on eBay!

  2. Hi from Australia. Thanks for this guide. My father and I are planning to do the same thing to a soon to be purchased red dot for his square four.