leaking seal drive shaft

RoGo60

RoGo60

New member
Location
Breskens The Netherlands
hello, after overhaul of my 750SF (1972) the outgoing shaft seal keeps on leaking a few drops, I have renewed the small seal clutch, main seal and spacer 5th gear. what can be wrong?
Also my frame number is 7779, but not clear wat model SF0 or SF1,  have drum brakes and old fashioned lamp with light switch on the lamp, Dell L'orto 30 carb's with no airfilter.
Thanks for any reply
 

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Is first series SF
Click to expand...
No, 2nd series. 1st series has e.g. the old tank,
but different to 750S with a flip cap, all of them
have Smiths clocks (although early 72 SFs might
have the Smiths too).
This bike is known as SF 0, or SF 72.
I always use sealant over the seal's outer diameter
and the adjacent case metal, too.

Ernesto
 
Certain that the seal is leaking?

On rare occasions, the spacer is not oil tight.  Although it is a press fit on the output shaft, oil sometimes finds its way behind the spacer and exits through the shaft splines...  especially if it has been removed and replaced in a different orientation.  The inner diameter of the spacer usually shows witness marks of previous installations, the surface is then quite rough and will not seal well.  You can swap the seals on a weekly basis and it will still leak.

piet
 
RoGo60 said:
thanks for replies, the spacer however is new and should seal, not? maybe it will stop leaking after it has run for more miles?
Click to expand...

... and you believe in Santa Claus. :D

piet
 
Bit like adding air to a flat tyre and hoping it stays up, always my first option. Still do that even if its never worked yet
 
sfcpiet said:
Certain that the seal is leaking?

On rare occasions, the spacer is not oil tight. Although it is a press fit on the output shaft, oil sometimes finds its way behind the spacer and exits through the shaft splines...  especially if it has been removed and replaced in a different orientation.  The inner diameter of the spacer usually shows witness marks of previous installations, the surface is then quite rough and will not seal well.  You can swap the seals on a weekly basis and it will still leak.

piet
Click to expand...

I had that issue on 2 of my other bikes (non-Laverda) with similar design. I stopped it leaking by putting sealant goo onto the rear face of the spacer sitting against the bearing inner ring. I did the same on the Laverda as a preemptive measure when rebuilding the engine.  Do not forget to degrease the surfaces thoroughly before adding the sealant. A few Q-tips nicked from the missus might come in handy when you got to do this on an assembled engine. :-X
 
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