Oil leak by the axel/sprocket

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dessmo
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Oil leak by the axel/sprocket

Post by dessmo » Thu Aug 17, 2017 6:58 am

I have an oil leak by the axel on the right side were the sprocket is.
The leak is between the axel and metal ring, seem like the oil comes out along the profile were the sprocket is attached. Any tips on how to fix this is highly appreciated.

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Magnus
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ducadini
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Re: Oil leak by the axel/sprocket

Post by ducadini » Thu Aug 17, 2017 11:06 am

Are You sure the nut was tight enough ? If it's loose, it leaks.
Check the bush for cracks or dents so it doens't seal against the sprocket.
Be sure the crankcase breather tube isn't obstructed or clamped between something.
This makes the pressurewaves in the crankcase go up and forces the oil out, even with new seals.

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dessmo
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Re: Oil leak by the axel/sprocket

Post by dessmo » Thu Aug 17, 2017 12:09 pm

Thanks ducadini for your Reply. Seems like both your explanations might be in effect. The nut was not very tight, actually quite lose. I don't have the special tool, but was able to dismount the sprocket by hand power. Any tips on how to tighten it up when you don't have the tool? If I understand you correct there should be a bush on the inside of the sprocket that makes a seal towards the engine? I only have the three parts that you see on the picture under. Just to be sure, which side of the sprocket should face the engine? when I took it lose the thickest par were facing towards the engine.
Should there be used any lock tight or sealer between the nut, bush and sprocket?

The plastic tube does also have also a squeeze, so I guess this might lead to a to high pressure in the franc case. So maybe the combination is the reason.

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Last edited by dessmo on Thu Aug 17, 2017 9:40 pm, edited 1 time in total.
Magnus
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robax
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Re: Oil leak by the axel/sprocket

Post by robax » Thu Aug 17, 2017 9:15 pm

The thick side of the sprocket goes on the outside, and there should be a spring inside that tube to stop it collapsing.

Get a new nut and washer and don't skimp on applying the correct torque for this, preferably with the proper tool. Highly dangerous to mess this one up.

Regards
Rob
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Re: Oil leak by the axel/sprocket

Post by robax » Thu Aug 17, 2017 9:17 pm

p.s no Loctite, just correct torque and a perfect fit between the nut and lock washer.
Rob - NZ
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1982 Ducati 900ss

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Craig in France
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Re: Oil leak by the axel/sprocket

Post by Craig in France » Fri Aug 18, 2017 12:18 am

As Rob says: fit a new tab washer and a new nut and use the proper tools to tighten the nut. Ideally, you need two: one to hold the sprocket, one to tighten the nut. Steve sells both:
https://store.bevelheaven.com/Chain-Spr ... ut-Socket/

Do the nut up to 50lb/foot.

A trick a certain Steve Wynne told me was to use two of the nuts with a dab of silicone on the threads. That works.

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Re: Oil leak by the axel/sprocket

Post by ducadini » Fri Aug 18, 2017 12:38 am

Parts manual 860 (all types are the same), page CB, part 095.
This ring creates the seal over the splines of the out-shaft against the seal in the crankcase.
It must be possible to pry it out and turn it around, so the seal is running on another part.
Check for dings and dents.
With dismantled engine, I fitted a 1RS type bearing (page KA part 2054) to prevent the outer seal leaking.

The special tool to tighten the nut is available at Steve's.
I used reinforced airhose for the breather tube but they also get warm and can run flat.
Originally there is a light spring in the tube to prevent it from collapsing.

ciao
ducadini
Last edited by ducadini on Fri Aug 18, 2017 12:43 am, edited 1 time in total.
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dessmo
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Re: Oil leak by the axel/sprocket

Post by dessmo » Fri Aug 18, 2017 12:40 am

Thanks for the assistance,

Found this in the workshop manual, should there be a spacer between the sprocket and the engine. Mine did not have one, and I can find this part looking at the diagrams.

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Re: Oil leak by the axel/sprocket

Post by dessmo » Fri Aug 18, 2017 1:11 am

Thanks Ducadini,

Found the part 095 at page CF, But I am not sure if I have it or not. As you can see on my first picture there is a metal ring visible on the inside of the black rubber seal, is this the spacer?

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Re: Oil leak by the axel/sprocket

Post by dessmo » Fri Aug 18, 2017 2:29 am

Learned a lot today from your posts and working on the bike. Fond the spacer which I guess is between the shaft and the rubber seal. Was able to turn it around, turns around with the shaft. So I guess the conclusion is to order a new nut, the washer and the special tool to so I am able to set the right torque. The tool is rather expensive, but I guess there is no way around it. Thanks for the assistance, appreciate it!
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Re: Oil leak by the axel/sprocket

Post by ducadini » Fri Aug 18, 2017 3:34 am

I turned a steel pipe to the correct ID, welded four tabs on the inside and corrected all by hand to fit the nut.
In the 70's it just wasn't that easy to order Ducati tools ;-)
To clamp the sprocket I use an old chain with a piece of steel bolted to it.
Torquing the nut IS already difficult , standing on the brakepedal just adds more complications ;-)
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Lumpy
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Re: Oil leak by the axel/sprocket

Post by Lumpy » Fri Aug 18, 2017 4:10 am

Very odd. I`m sure that on one of my bevels that at the back (the inside) of the spacer (part 095) is chamfered off and there is an O ring in there to seal it against the gear. Can`t remember if it was on the 82 model or the 76. In which case the spacer can't be turned around and it would be worth replacing the O ring while your in there. Also the small seals on the selector shaft are prone to leakage. I had to replace those on my GTS many moons ago.
And good advice to NOT use loctite. The previous owner of my 82 SS had loctited the sprocket retainer on and the battle to remove it was monumental.

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Re: Oil leak by the axel/sprocket

Post by ducadini » Fri Aug 18, 2017 5:28 am

Earliest bevel-engines I have is a 73 sport, latest a 82 Darmah.
Never seen any o-ring near the out-shaft.
Maybe a possible solution someone tried but I wonder how it was done without compromising the shimming.

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wdietz186
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Re: Oil leak by the axel/sprocket

Post by wdietz186 » Fri Aug 18, 2017 7:52 am

Having chased oil leaks at that point I have found that using silicone sealer on the faces of the sprocket and the spacer behind it will pretty much eliminate oil leakage at that point. Ducati relied on the tightness of the sprocket to stop leakage at that point and it works, as long as the surfaces are perfect. They are sometimes. The reason oil leaks there is because the spline is cut back under where spacer sits so oil can move under the spacer and sprocket and out any gaps on the faces. I use the semi hardening sealer[3 bond,Yamabond,Hondabond they're all the same] like is used between case halves, side covers,etc. After that leak is fixed you'll probably have another at the end where the mainshaft pokes through the end of the output gear. There is a very thin seal behind the circlip that almost always leaks. The usual remedy is to tap in another seal on top of the original as removing the seal is very difficult. I think as many as three can be pushed into the available space. Usually one extra seal does the trick. You will have to make a seal driver to install it, I turned down a piece of PVC pipe to tap it in with. I used a plastic bottle cap that was the right size on the first one I replaced.

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Re: Oil leak by the axel/sprocket

Post by Lumpy » Fri Aug 18, 2017 4:59 pm

It`s true it`s true Ducadini!!! The only thing I can think of is it was retro fitted by the previous owner. Just went back over my service records for my GTS and I replaced the o ring with the last chain and sprockets replacement. The inside bore of the spacer had been chamfered to accomodate an o ring which when you think about it is not a bad idea. Positive seal and no need for gum in there.

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