Modern crank seals and where can i find them

[kawahonkabsa]

Hi All,
Anybody receintly bought modern lip seals as fitted in Scott Technicalities?
I am thinking of upgrading my 600 as there is a constant leak from the LH side
and getting worse.
If you have done this mod. how did it go always interested.

Thanks Mick

[Anonymous]

Hi Mick,

The seals are easy – most seal stockists have them in, but the fun starts with putting something in the holes the glands leave. You need something to take the end float/thrust and also if you are using a Pilgrim or dripper for the mains you need one way valves in the oil feed lines or it will just shuttle the oil backwards and forwards in them rather than allow a through flow.

For the end float I’ve seen bronze rings fitted to the crank thread, and also built up roller bearings a-la Silk.
If you do it then leaks will be long forgotten, but it is more involved than just taking out the glands and putting in synthetic seals as the glands do more than just seal.

Which specific page/chapter/reference are you looking at in technicalities?

Regards,
Richard

[Roger Moss]

It is a preferred option when I rebuild engines to substitute the hard screwed rings on the back of the crank that form the rear retaining wall to the main bearing rollers with a bronze ring that performs the same duty. The back side of this ring acts to control end float of the crank assembly and so does away with spring loaded hard metal to metal face glands which are intolerant of oil starvation and alignment inaccuracies, if the flywheel tapers have bee compromised as many have.
I fit a bronze insert in the cup centre bore which is a housing for a synthetic seal. The whole system is completed with a non return valve under each oil feed elbow on the inner top of the case. If you have oil leaks then either your gland is not seating due to taper axis errors in the flywheel, or more likely the old problem of the crankcase metal expanding when hot and providing a small gap between the cup and the cup bore at the inside rear of the cup, where the oil hole is very near the inner edge. Scotts tried to allieviate this by spinning a groove but it was not successful. A modern cure is a thorough degrease and apply a good wiped bead of RTV silicone to fill the corner betwwen cup and case. This will expand and contract with temperature variations. Try this first as the system I use is really part of a rebuild. Roger Moss

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