Triumph Repair: Speedo, tail shaft, visegrip

Question
Hi Jim.  My speedo decided to quit working recently, although the cable is actually not all that old (maybe 1-2 years). Oddly, the inner cable spins when I'm in reverse, but will not spin going forward. Any ideas? Could the very end of the cable have snapped off in the drive? I've tried to scrape out any broken bits from the hole on the tranny, but nothin. It's a '71 MkIV gearbox.

Thanks,

Steve

Answer
Steve,

The gearbox end of the inner cable was simply squashed to flatten it enough to grab the square hole in the drive gear.

Two thoughts.  One is that the drive gear setup is a bit worn and there's enough clearance to "miss" the cable going foward but not in reverse.  

The other is that the gear on the tail shaft is loose or worn, or the mating gear in the gearbox housing is worn.

One thing to try is to carefully crimp the end of the cable just a bit with a pair of channel lock or visegrip pliers and see if that improves the "bite" in the drive gear.

If not, it might be time to start digging into the trans speedo drive gear setup.


Cheers,

Jim