oil leak (speedo drive)

[Rich]

Any advice on how to stop the gearbox oil leaking from the speedo drive, the bike is a 1958 A10 so standard swing arm box,
Thanks Richard

[morris]

Must be by far the dumbest design ever. Tried several things to stop mine leaking, but no success.
Bit curious if anybody found a solution? Hoping for the best but expecting the worst.....

[bsa-bill]

clean all the bits with petrol then fill it up with silicon before screwing the nut on, works for a while but not forever

[duTch]

  Isn't there two types,? one at least(maybe the later type) has an 'O' ring, have you checked that ? Or is it leaking from the spindle with the scroll, assuming it's an original with the scroll running the correct way??
 All I can come up with for now, mine's maybe not leaking (enough to notice) for now, but if it does I guess will look into it further...
 cheers

[KiwiGF]

Because the outer plastic was damaged I used a self vulcanising sticky rubber tape wound around the cable, gearbox end and shrink tube over that, covering about 150mm of the cable, no leaks  

[muskrat]

Same as KiwiGF but with electrical shrink wrap. Also added O rings either side of the flare fitting. Good for 2 years now.
Cheers

[Greybeard]

clean all the bits with petrol then fill it up with silicon before screwing the nut on, works for a while but not forever

Better still use silicone.  

Mr A. Pedant

[Rich]

Thanks all, I had a search after I posted and this question had come up before, Groilly and another (I cant remember who) suggested an O ring and PTF tape , so I am going to fit an O ring between the fibre washer under the nut covered in silicone and ptf tape on the threads, the cable has already had the heat shrink treatment. That should sort it. (famous last words)

[bsa-bill]

Better still use silicone.  wink

no too messy, I stuff old chips from PCs in there

PS ( this may be a lie)

[Rich]

 

[orabanda]

There is a guaranteed fix for this leak.

I pack 3 or 4 off 1/16" cross section o-rings with the same ID as the speedo gear shaft, along the shaft. The part no is BS-010; available from your favourite o-ring supplier.

Remove the (long) brass bushing that the speedo gear runs in; warming the outer cover with a heat gun helps!

Bore out the speedo cable end of the bushing to 0.384" (boring is preferred to drilling), deep enough to accept the stack of o-rings.

I also machine a groove on the OD of the bushing to accept a 1/16" cs o-ring; can't remember the size! This guarantees no leakage around the outside. However, the main culprit is the speedo drive (ID).

Go find your supply of vaseline and coat the BS-010 o-rings (and the one on the OD; also chamfer any sharp edge in the casing so this o-ring is not cut when installing the bushing).

Push the o-rings into the bore you have machined, in the bushing.

Make up a simple tool out of tube to stop the o-rings from pushing out of the housing, and push the speedo drive into place from the rear of the bushing.

Warm the outer gearbox casing to about 70C, and fit the bushing back in place. Insert the locking cheesehead screw whilst still warm.

When cold, fit a fibre washer under the bushing lock nut, and do up nut.

I have also used the copper backed petrol tap sealing washers (with bonded rubber inner piece). From memory the washer that fits 1/4" BSP, is the correct size.

 It will squash down sufficiently to fit the speedo cable, and the rubber lips will seal against the thread.

Richard

[Rich]

to complicated for me to understand I lost the plot at the first lot of O rings.
But thanks anyway

[duTch]

 thanks Richard, will process that better later, and thanks for the reminders that I also had forgotten I did the full length of my cable with heat-shrink, pick a colour-any colour...!..mainly as the outer had come in contact with header pipe....!
  
 cheers

 Yo Rich, you rounded me up....