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Leaky rear end


BillyB

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No not in my underwear, but on my 03 Lemans. I have gear oil leaking from the rear end and it ends up dripping onto the wheel when its on the sidestand. Anyways looking at the parts fiche there's an o-ring (part 24 in the diagram) and a seal (part 27). I should probably just replace both, but if one of these is a common failure, can you let me know, or if neither of these is the likely culprit please chime in. Thanks.

v11_rear.jpg

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Most likely the big seal, #27. Simple enough to replace the O-ring, #24, as well. The large seal is not hard to change. 
 

If the leak appears on the right side of the rear drive, the small seal, #10, needs changing. The crown wheel bearing,#12, must be removed and replaced for this.

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On the rear stand (bike level) there's no leak, it only leaks when on the side stand but seems to be leaking out from the bottom of the assembly towards the inside (not out the right side). I'll replace both the seal and o-ring and go from there. Thanks docc.

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On 11/30/2021 at 5:40 PM, docc said:

Yeah, I fought with my rear drive for ten years. It was miserable. Pretty sure that’s just one of the threads…..

it’s also known to be one of the heaviest, ultimo densio pieces of engineering known to man

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On 12/1/2021 at 3:23 PM, stewgnu said:

it’s also known to be one of the heaviest, ultimo densio pieces of engineering known to man

Hey! my collection resembles that remark!

IMG_8827.jpg

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On 12/1/2021 at 5:10 AM, docc said:

Most likely the big seal, #27. Simple enough to replace the O-ring, #24, as well. The large seal is not hard to change. 
 

If the leak appears on the right side of the rear drive, the small seal, #10, needs changing. The crown wheel bearing,#12, must be removed and replaced for this.

Docc's second suggestion is the worst news, but is actually more likely. if the RH end of the crown wheel has rust pits on it, then the #10 seal needs to be replaced, after you blend out the rust (if minor) or fit a seal saver (if rust will chew out the new seal). Be aware of the seal orientation. It looks to be in backwards when correctly fitted.

A leaky #10 seal allows oil to travel along the axle cavity inside the crown wheel, and the leak shows coming out the LH side of the box.

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Hi,

While we're on the rear drive....is there anyone manufacturing or have available a spanner socket for the ringnut (#18) that retains the pinion assembly?  I'm at a point where I've got a ringnut on order for the purpose of making my own spanner.   I'd prefer to buy one already made since my machine shop consists of a cut-off wheel & Dremel tool.  

Art

 

Rear Drive Spanner.docx

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Also, I haven't figured out how to post pics here.

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49 minutes ago, guzziart said:

Hi,

While we're on the rear drive....is there anyone manufacturing or have available a spanner socket for the ringnut (#18) that retains the pinion assembly?  I'm at a point where I've got a ringnut on order for the purpose of making my own spanner.   I'd prefer to buy one already made since my machine shop consists of a cut-off wheel & Dremel tool.  

Art

 

Rear Drive Spanner.docx 100.54 kB · 1 download

Yes it's called a hammer and drift. It doesn't need to be too tight.

Ciao

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Hi Phil,

I originally started down that road but after chewing up a couple brass drifts I switched to a steel one that began to destroy the nut.  So, I figure before I get to the point of no return, I'd make or get a spanner socket.  The drive is original to the bike and was replaced by the PO about 15 years ago because it leaked.  I'd like to get this unit back into the bike because it is low mileage (under 6k), nothing needs to be shimmed and the paint finish matches the engine & trans.   Yeah, I don't get why the ringnut is so tight other than maybe corrosion, the drive looks to have been well cared for during it's out of service years. Oh well.

Thanks,

Art

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What I did when I needed to remove the #18 nut was buy a half inch drive socket the exact right OD and then use angle grinder with a thin hard wheel to cutout the socket to create the tool. It only took about 30 minutes to create it and worked very well.

To hold everything while I removed the nut I reinstalled the rear end without the drive shaft and used the brake to hold everything from turning while I removed the nut. The nut was very tight, but worked well with a second person to hold the brake on.

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