Input rear drive leaking

[nielsv11]

Hey everyone!

I am new to this form and I hope you can all help me with something. Last week, returning from a drive, a saw some oil on my rear tire of my v11 scura. When further investigating, I saw that it was coming from the input side of the rear drive. I have looked around the internet and the forum here to see if anyone else has encountered this problem but sadly could not find it yet. I think it is the seal that has gone bad by a small stone or something that came into the drive shaft (Why did they make it open XD).

 

 

I have already looked into the maintenance manual but it did not go into much detail on the front side of the final drive. Now I was wondering if anyone has experience with replacing this seal and if they can tell me if there are things that I have to watch out for or if there are special tools I will need. Because I saw there is a special ring nut and I was hoping that it would not have to be loosened for the replacement of the seal. Thanks in advance!

[thumper]

Easy thing first, make sure the vent on top is clear.

[nielsv11]

Good point I guess just unscrew it and blow into it to check the functioning?

[p6x]

15 hours ago, nielsv11 said:

Last week, returning from a drive, a saw some oil on my rear tire of my v11 scura.

@nielsv11 I apologize, my initial reply was not complete. I did not realize I was missing the link to my particular issue. There is an o'ring between the pinion carrier, to prevent the oil from leaking out. The drive on my Quota maybe different, but the sealing principle remains the same.

I had a similar problem; it is more frequent than you think... 

Edited June 4 by p6x

[Lucky Phil]

7 hours ago, p6x said:

I had a similar problem; it is more frequent than you think... 

Well thats totally misleading. Different rear drive unit and in your case the drain plug fell out due to poor maintenance practices. This is how rubbish gets propagated on the internet and therefore I'm highlighting it straight away.

Phil

Edited June 4 by Lucky Phil

[p6x]

51 minutes ago, Lucky Phil said:

Well thats totally misleading. Different rear drive unit and in your case the drain plug fell out due to poor maintenance practices. This is how rubbish gets propagated on the internet and therefore I'm highlighting it straight away.

Phil

I made a mistake as I had two different tabs open. I have edited my post to include all the information I had initially planned to provide.

Interesting that you automatically assumed I was purposely trying to be deceptive.

[docc]

@nielsv11,

Once that wet, it can be hard to know where a leak started.

Perhaps clean up, apply a "foot powder" and go for a short ride (after ensuring these is enough oil in the box!). 
 

The powder will discolor at the source of the leak.

[pete roper]

3 hours ago, p6x said:

I made a mistake as I had two different tabs open. I have edited my post to include all the information I had initially planned to provide.

Interesting that you automatically assumed I was purposely trying to be deceptive.

I don’t think that the suggestion was that you were trying to be deceptive, simply that the information you were imparting was wrong and not relevant. For people seeking answers to specific questions it is important to not muddy the waters with irrelevant information and the fact is that a drain plug falling out has precisely nothing to do with a leaking pinion seal.

Oh, and a quick edit regarding your edit. The sealing principle on your Quota’s bevelbox and that of a V11 are entirely different! The pinion on the Quota box is unsealed. All the O-rings on the carrier do is prevent oil leaking out between the pinion carrier flange and the swingarm and box casting. The front bearings are unsealed and in fact the box breathes into the swingarm! The V11 box is sealed and breathes via the breathe installed in the case.

WRT the pinion seal on the V11 box I’ll have to go on memory as I haven’t done one for fifteen or more years but, like so many other Guzzi final drives, the construction is a bit, errr, unconventional!

I do believe that the ring nut as it is called needs to be removed to extract the seal, (I’m happy to be corrected if I’m wrong.) but the reason the seal might leak should be examined as well.

The V11 pinion support assembly is all a bit odd. Unlike most pinion mounts the shaft of the pinion is not supported by opposed tapered roller bearings. The advantage of that *Conventional* set up is that both the support and end thrust on the pinion shaft are taken by the opposing bearings. With the V11 pinion though the forces are dealt with separately. The rotational load is taken by a substantial roller bearing but the end thrust is taken by a large caged ball race. These are both ‘Contained’ in one large outer race BUT the outer race of the ball part of the bearing is split and the whole lot is clamped together by the ‘Ring nut’ which contains the seal and the seal runs on a spacer between the centre race of the queer two part bearing and the pinion lock nut. 
 

Now also for the first time in a Guzzi bevelbox the pinion has a support bearing inboard of the head of the pinion. It’s a small needle roller similar to the pilot bearing for a gearbox input shaft in some car flywheels. One unfortunate thing though is that it tends to not get oiled very well due to its location and this can lead to brinneling of the outer race and premature failure. If this happens and play/clearance becomes excessive it will lead to increased loading on the two components of the two part shaft support bearing. Now being a Guzzi and therefore being built like a brick shithouse this doesn’t often seem to cause problems but if for instance the box is run low on oil or worse yet gets water in it brinneling and wear can occur in the support bearings and if this happens the pinion shaft can begin to run off its axis. This will have dire consequences for the mesh of the gears and their life but one of the first signs that something is wrong will likely be the pinion input seal blowing and the resultant oil loss.

Now I’m not saying that anything like this has happened, just that you should be aware it can. Certainly if my bike had popped it’s front seal I would probably take it upon myself to pull the crownwheel cover plate and examine the teeth of both gears and then while it was off have a really good tug and thrust at the pinion just to see if it had any axial or lateral play. If it does I’d investigate further rather than simply sticking in a new seal and calling it sweet because the new seal likely wouldn’t last very long.

Edited June 5 by pete roper
Just covering extra stuff.

[Lucky Phil]

3 hours ago, p6x said:

I made a mistake as I had two different tabs open. I have edited my post to include all the information I had initially planned to provide.

Interesting that you automatically assumed I was purposely trying to be deceptive.

No I assumed you were just firing off a post without considering it would be misleading.

Phil

[Lucky Phil]

19 minutes ago, pete roper said:

I don’t think that the suggestion was that you were trying to be deceptive, simply that the information you were imparting was wrong and not relevant. For people seeking answers to specific questions it is important to not muddy the waters with irrelevant information and the fact is that a drain plug falling out has precisely nothing to do with a leaking pinion seal.

WRT the pinion seal on the V11 box I’ll have to go on memory as I haven’t done one for fifteen or more years but, like so many other Guzzi final drives, the construction is a bit, errr, unconventional!

I do believe that the ring nut as it is called needs to be removed to extract the seal, (I’m happy to be corrected if I’m wrong.) but the reason the seal might leak should be examined as well.

The V11 pinion support assembly is all a bit odd. Unlike most pinion mounts the shaft of the pinion is not supported by opposed tapered roller bearings. The advantage of that *Conventional* set up is that both the support and end thrust on the pinion shaft are taken by the opposing bearings. With the V11 pinion though the forces are dealt with separately. The rotational load is taken by a substantial roller bearing but the end thrust is taken by a large caged ball race. These are both ‘Contained’ in one large outer race BUT the outer race of the ball part of the bearing is split and the whole lot is clamped together by the ‘Ring nut’ which contains the seal and the seal runs on a spacer between the centre race of the queer two part bearing and the pinion lock nut. 
 

Now also for the first time in a Guzzi bevelbox the pinion has a support bearing inboard of the head of the pinion. It’s a small needle roller similar to the pilot bearing for a gearbox input shaft in some car flywheels. One unfortunate thing though is that it tends to not get oiled very well due to its location and this can lead to brinneling of the outer race and premature failure. If this happens and play/clearance becomes excessive it will lead to increased loading on the two components of the two part shaft support bearing. Now being a Guzzi and therefore being built like a brick shithouse this doesn’t often seem to cause problems but if for instance the box is run low on oil or worse yet gets water in it brinneling and wear can occur in the support bearings and if this happens the pinion shaft can begin to run off its axis. This will have dire consequences for the mesh of the gears and their life but one of the first signs that something is wrong will likely be the pinion input seal blowing and the resultant oil loss.

Now I’m not saying that anything like this has happened, just that you should be aware it can. Certainly if my bike had popped it’s front seal I would probably take it upon myself to pull the crownwheel cover plate and examine the teeth of both gears and then while it was off have a really good tug and thrust at the pinion just to see if it had any axial or lateral play. If it does I’d investigate further rather than simply sticking in a new seal and calling it sweet because the new seal likely wouldn’t last very long.

The real problem with the input shaft seal is Pete that the pinion nut has to be removed to change it and that's a right bugger as you know.

Phil

[pete roper]

3 hours ago, p6x said:

16 minutes ago, Lucky Phil said:

The real problem with the input shaft seal is Pete that the pinion nut has to be removed to change it and that's a right bugger as you know.

Phil

I thought it could be plucked out with the old self-tapping screw through the face of the seal trick and a new one slipped over the nut?  As I said though I haven’t done one for a very, very long time!

[Lucky Phil]

1 minute ago, pete roper said:

I thought it could be plucked out with the old self-tapping screw through the face of the seal trick and a new one slipped over the nut?  As I said though I haven’t done one for a very, very long time!

I had a quick look at the one you gave me in bits and the problem is the nut pulls up against the seal inner running sleeve and the nut is a larger dia than the seal running face. You pull the whole pinion shaft, bearing and seal as a unit with the nut in place if you like. I remember you saying the easiest way to remove the nut is with an windy drill and a cutting disk. 

[MartyNZ]

You can see seal ID running face in the pic.

I could send you the socket to undo the bearing retainer nut if you didn't live on the other side of the planet...

  

[Lucky Phil]

21 minutes ago, MartyNZ said:

You can see seal ID running face in the pic.

I could send you the socket to undo the bearing retainer nut if you didn't live on the other side of the planet...

  

How did you hold the assembly while you undid the hex nut?

Phil

Edited June 5 by Lucky Phil

[MartyNZ]

Since I needed to drill out the piece of the nut driven down into a  keyway to lock it, I kept going and stitch drilled the nut so I could split it. Tightening a new nut meant that I had to get a better way, so I made wood clamping blocks to grip the pinion in a vice. I should have made the clamps first.