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Advice For Kickshaft Seal Replacement

Posted: Tue Apr 24, 2018 1:25 pm
by Old905Duc
Hi,
Oil seems to be seaping from the kickstart shaft of my 1975 860GT. I was first suspecting the alternator cover gasket since I had the cover off. However replacing the gasket did not resolve the leakage. I am now suspicious of the kickstart shaft seal. I have purchased a new shaft seal and a new alternator cover gasket. I have removed the cover and attached a few pictures of the shaft and original seal as originally installed. Removing this seal with the shaft installed seems to be a bit of a challenge. I was told that it can be done by using small picks to tear away the rubber and then hook the back of the seal. However extreme care is needed not to scratch the sealing area of the shaft. I was also told that often the seal bore in the case is deep enough to stack two seals. However mine does not appear to be so deep ....... unless the orginal seal is not fully seated against the shoulder of the bore(?).

Before I tackle this repair I am looking for advice from the forum. I have no intention of splitting the cases to address this. Can anyonde advise how best to remove this seal with the kickstart shaft still inplace? I would greatly appreciate your thoughts and direct experience in performing this repair.

Thanks all.
Old905Duc
The attachment Ducati Kickshaft Seal 1.jpg is no longer available
Ducati Kickshaft Seal 1.jpg

Re: Advice For Kickshaft Seal Replacement

Posted: Thu Apr 26, 2018 6:52 am
by in-two
S.O.P. for this seal is to whack another one in on top of it, I did this on my GTS many years ago and it worked. It is unlikely that the seal is fully home on it's shoulder and gentle tapping with a suitable hollow drift should move it in enough to make room for the new one. If that fails then a possible technique for removing the seal is to drive two thin, long, sheet metal (self tapping) screws at 180 degrees to each other into the rubber part, then pop the seal out by levering with a small prybar on the screw heads. This particular seal is a bit thin for this but it could work if you find the right screws and the metal seal casing is not too corroded into the housing. Have fun...

Re: Advice For Kickshaft Seal Replacement

Posted: Thu Apr 26, 2018 7:24 pm
by Old905Duc
Hi,
Thanks for your reply! I actually received the same input from others on a facebook Ducati group. It worked! I made a delicate drift from a finishing nail and was able to push the old seal back far enough to make room for a new seal. This is much better than tearing things up trying to pull out the old seal. Anyway, now I am about to install the new seal. After looking at the seal, I decided that the open "compression spring" side of the seal faces toward the engine, and the closed side (with part number, etc. info) faces outward and is visible after installation. Do you agree?

Also, others have suggested putting a tight fitting o-ring on the shaft and rolling it up against the seal as an additional secondary seal. Sounds like a good idea and I will try it. Additionally, reducing crankcase pressure by plumbing a reed valve into the breather line is another interesting idea. I may try this but it requires a little extra engineering. It has the additional benefit of reducing pumping losses and freeing up a little power. This is a longer term project that seems interesting.

Thanks for your help. I am just about done with this one. BTW I attached a picture showing the ample room now available for the new seal!

Happy riding!
Old905Duc
Ducati Kickshaft Seal 3.jpg

Re: Advice For Kickshaft Seal Replacement

Posted: Fri Apr 27, 2018 1:27 am
by in-two
Happy to confirm your solution! Yes, spring side of seal faces towards the oil source. Another tip, put a suitably sized o ring between the two seals,
i.e inner (old) seal, o ring, new seal. My 900ss has an original, old school flapper valve on the breather and does not leak from the KS shaft, no idea if these two facts are causally linked...
Have even more fun.

Re: Advice For Kickshaft Seal Replacement

Posted: Fri Apr 27, 2018 12:29 pm
by ducadini
Since this shaft (and the gear on it) is above the highest oil-level, it is plausible that excessive crankcasepressure triggered the leak.
Minimum diameter of the tube is the ID of the black piece above the crankcase.

ciao
ducadini

Re: Advice For Kickshaft Seal Replacement

Posted: Mon Apr 30, 2018 12:54 pm
by Old905Duc
Thanks for your reply. Actually I have no tubing on the crankcase breather. I have installed a K&N filter directly to the plastic top of the breather. The filter vents to atmosphere. However I am thinking to install a reed valve between the breather and the filter to (potentially) create a slight negative pressure in the sump.
Ducati 860GT Breather.jpg