Moss Gearbox

[keithjecks]

I have a 1937 16/70 which has a speedo that doesn't work. The speedo drive is an annular worm gear that is on the splined output shaft. It engages with a pinion on the end of the speedo drive cable. On my car, the annular gear is missing from the gearbox. I have stripped it down to fit a gear I have from another gearbox, only to find that the shaft on mine is a couple of mm too thick, though it has the same number of splines.
   
   A few questions:
   
   > does anyone know where I can get the correct part from?
   
   > If not, does anyone know an engineering shop that could make the internal diameter of the gear larger so it fits the shaft of my gearbox?
   
   > If I do that, am I right in thinking that the external diameter of the part I have would be the same as the original fitting?

[Robin A Woolmer]

Keith
   'www.scparts.co.uk' supply parts for jag /moss gearboxes, in terms of grinding the internal bore, most good machine shops would have a cylindrical grinder which could be used but you would need to ensure the gear is ground concentric, also you would need to check the hardness requirements of the material is Ok once ground.
   You could discuss the modification with Eric or Ian at Neve Engineering who i am sure could assist, 01273 400 731.
   
   Robin

[1936ACE]

Hi Keith, we seem to be following a similar path.  When my speedo drive packed up I got a replacement (inner and outer) from Richard at RW Racing (he advertises in ACtion).  Be aware that there are at least four types, and at first sight they all appear the same - it's only when you put two next to each other and count the teeth and direction of rotation that the differences are apparent.  Mike

[keithjecks]

How muuch did the bits cost, as a matter of interest?

[1936ACE]

Can't locate the bill at the moment Keith, but from memory it was just under £100 - plenty enough but cheaper than getting a new one machined up.