Had a difficult to trace oil leak,on my B31 and found it was from the speedo cable.It had been touching the exhaust and burnt several inches of the plastic sheathing off and was dripping from there.I have wrapped the cable drive at the gearbox with kitchen roll and it is not leaking from there.
My question is;is gearbox oil supposed to be in the speedo cable,if so,I need a new cable.If not,then the speedo drive in the gearbox needs inspection.
Thanks, Terry.
Pretty much inevitable.
Unless you have no play between Speedo drive spindle and the housing. As you need clearance for spindle and cable to turn.
A small o-ring would help but not much space to fit it. The leak between the case and threaded boss is easier as no movement there.
I seem to remember seeing an article on the o-ring mod.
Its not a bad thing, oil creeps up the cable and keeps it lubricated. The trick is to fit a spring over the cable or get one with a spring that keeps it off the exhaust. Its only a problem if it reaches the speedo but its only oil.
The main thing is to keep oil out of the speedo head. If the cable inner at the speedo head looks oily wipe it off.
BSA added an O ring to the speedo drive during 1962. The O ring is flimsy and in my experience soon fails - my A10 has one and still leaks a bit. This is covered on parts service bulletin G19 from March 1962.
The modified drive can be seen in the photo below.
If the cable outer sleeve is damaged you can repair it using some heat shrink tubing with adhesive. See the last photo, I used heat shrink with adhesive 16mm diameter 4:1 shrink. This is large enough to slide over the cable retaining nut and shrinks tightly on the cable when your chosen source of heat is applied. I got mine on ebay.
Thanks for the replies folks.
Took the speedo cable off from the gearbox and there was no fibre washer as is shown in the Haynes manual.
Put in a very small fibre washer in the ferrule and it seems to have stopped leaking.That's either fixed it,or the gearbox has run out of oil.
Whatever,I have ordered some heat shrink tubing as suggested by Julian S.