speedo gearbox

[clevtrev]

Having just read Paul Ennis' article in MPH 669, I jalouse that the reason for the "Landrover" gearbox being bigger, and therefore "impure", is that it holds nylon gears, not steel, and they have to be bigger. I know that some right angle boxes do contain nylon gears, because I've had them strip, on other (lesser...) bikes. In turn, that suggests is that what one needs to be looking for is a treasure trove of pre-1954 Landrover speedo spares, c/w right-angle boxes with steel gears. At 1954 prices........
I know that the 5" speedo was made by Smith exclusively for Vincent (PEI says so) but am guessing that the gearbox was an off-the-shelf item.

It was probably available in France, as it`s 100% metric.

 

[Tom Gaynor]

Next you'll be telling me that Eddy Stevens is half French........

I found another "large" right-angle gearbox (while looking for something else) which lacked an end cover. The gears are indeed nylon (or at least plastic).

 

[vapide]

There seem to be at least three gearboxes one may encounter on 5" Shadow clocks. As I understand it, the original ones had non-threaded inputs, so they could only be used with the original gearbox which clamped over the input stub. Repros usually had a standard movement with a threaded stub so a cable could be attached directly, but were supplied with a Smiths BG2410/00 gearbox which has a captured knurled screw which screws down over the threaded input stub. Later repros seem to use Landrover gearboxes. I think the Smiths is a little smaller but can't swear to it. Just to make it more complicated, there was a modification available in the old days to eliminate the troublesome gearbox by putting a threaded input on the original speedos so the cable could be run straight out of the back, and its possible an original speedo so modified could have been fitted later with the BG or Rover box. Doug Wood apparently has a source of the original style boxes which he uses in his repros. The Smiths BG is no longer made but NOS ones turn up fairly regularly (I bought a couple recently for $50 each), and the Rover one seems to be readily available.

 

[Paul Ennis]

5" speedo gearboxes

Hugo, I guess that your problem gearbox was the early type as mentioned by dave gs, pre-dating the ones that I am used to. It seems logical then, that the steel thrust washers and the 3/32" ball bearing were Smiths' cure for breaking cables. That is until (after about 50 years) the gears wear out!

 

[Hugo Myatt]

Paul, I guess your are right. I certainly don't remember any steel thrust washers but I am not going to take it apart to look. If it ain't broke don't fix it.