Tachometer drive leak fix (2016)

Dave , whats going on there, sounds like you have a lot of pressure that the reed Vv cant get rid of which would surprise me ?
Regards Mike

I would be surprised if heat from the exhaust would have any effect. Not sure, but could the spiral wound cable pump the oil up to the speedo. Cant remember which way the spiral is wound etc. Its not good to get oil in the speedo though.

I dont really know what is going on until I pull it apart.

Not too long ago the Newish Venhill cable broke and sheared the drive spade too. I had a spare spade and just used my old cable, and it is since then the leak has started.

I will have to pull the exhaust and the drive and take a look.

gortnipper said:

I wouldn't be concerned if the leak was at the tach drive, but it is spewing out the top of the cable into the tach and running down the headlight shell and fork.

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Well... that truly sucks.

Some time ago [ too long to remember ] I had a leak at the speedo drive area. The groove for the "Ö"ring was too wide so I fitted TWO "O"rings. It didnt leak after that. Maybe the one "Ö"ring slopped around too much!

kerinorton said:

Some time ago [ too long to remember ] I had a leak at the speedo drive area. The groove for the "Ö"ring was too wide so I fitted TWO "O"rings. It didnt leak after that. Maybe the one "Ö"ring slopped around too much!

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I am planning on pulling it all apart tonight to see what the deal is. I am hoping the o-ring might be leaking if damaged from the cable and spade drive failures (which had slipped my mind when I first posted). That would be best case scenario - seeing as it was good all the way to Akaroa and for the rest of the year.

I remember thinking there was something archaic about the design. I cant remember if I put an "Ö" ring on the cable end itself. Let us know what you find. It should be simple to fix.

Was out of town for a few days, but I think I sussed it out.

As previously said, the cable and spade had sheared not too long ago.




I did pull it down and this is what I found in the drive housing. I didnt inspect the inside of the drive housing before, though I did spray it out with carb cleaner and air. Obviously that was a mistake, as I found a couple pieces of swarf that had probably been in the groove cut by the circlip when the failure happened. So the scroll in the gear shaft was forcing oil up and out past the damaged o-ring.



I cleaned out the drive housing, replaced the o-ring and put another new Venhill cable in it, and it seems to be holding oil again now. If it fails again, I will get a new housing with proper seal and a drive gear with no scroll.