Posted By : Chris Taylor, 20-Jun-2006,
04:37pm
What on earth has caused the speedo head to go bang? While cables can snap, and as the instrument itself wears, the readings can become more erratic
and inaccurate, but there is little to fail!
Anyway, as your 12/50 should have a single large dial, the only speedo that is a clear "fit" is a similar sized Smiths or Jaeger speedo. To deal with
diff ratios, you ideally want a speedo from any 1200 or 12/50, or the original single dial Vitesse 6 speedo will be close.
The gearing of a Spit Mk3 is the same as a Herald, so should read reasonably accurately, but has a smaller dial.
The same size dial was fitted to Minis and Minors, but I've no idea what gearing was used. I would expect cable end fittings to be the same, but have
not actually compared them. There is a reference number on each dial (small, and towards the bottom of the dial), which indicates something like
revolutions per mile. Off the top of my head, it is a number around 1000? You need the same number as your 12/50 speedo for the replacement speedo to
read the same. The other problem with something like a Mini or Minor speedo is what warning lamps are housed in it. They may have a different number of
warning lamps, and in a different colour and with different markings to the Triumph one.