Chaincase

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I pulled off the outer chaincase today as the chaincase sealing band was obviously worn out -- leaking oil was the obvious clue. I was wondering if anyone could suggest a better method of sealing the inner and outer (if one even exists).

Also, I'm posting a picture of the innards just because I'd be interested to know if anything seems awry here. This is my first time looking into this area so I don't know what would be considered normal. I was hoping to be surprised by a belt drive but no such luck(!).

Chaincase

Below is a picture of my outer chaincase.

Chaincase

As you can see there is quite a bit of wear where the left hand footrest is positioned next to it. It's not really noticeable when the footrest is bolted on, but I'm wondering if it is indicative of some larger problem, e.g., faulty positioning of the Z plate or the like. The wear really does seem more than a little excessive.

Cheers--

wrench
 

L.A.B.

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wrench said:
As you can see there is quite a bit of wear where the left hand footrest is positioned next to it. It's not really noticeable when the footrest is bolted on, but I'm wondering if it is indicative of some larger problem, e.g., faulty positioning of the Z plate or the like. The wear really does seem more than a little excessive.

One reason that the primary case joint leaks is due to the retaining nut being overtightened. This can distort the outer case, so check that the joint faces are flat.

The wear was most likely caused by somebody either falling off, or the motorcycle falling over and bending the footrest arm in against the case, and that could have caused some initial casing damage.

If the bike is then ridden with the arm bent in I expect the Isolastic mountings cause the primary cover to rub against the footrest mounting bolt causing the case to become even more damaged, until the footrest arm is replaced or straightened.

My own primary case bears a similar scar as I am sure many others do!
 
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I have a leak free primary on my 70.

Make sure the center bolt is correctly shimmed to the inner primary, In your case it's likely OK but if you know how, it wouldn't hurt to check.

I put a thin bead of silicone inside the channel on the inner primary where the O Ring goes, then installed the NEW O ring, making sure to push it in place all around. After wipping off the excess silicone which was forced out when I installed the O Ring I then put on the outer cover...

I have 2000 miles on my rebuild & have NO OIL LEAKS anywhere!
 
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L.A.B & Biker-man--

Makes perfect sense, all 'round, both the diagnosis and the prognosis. Makes sense if the bike hit the pavement at some point in its elusive history. Maybe a good shot to the footrest also caused distortion in the seals as well? If the outer case has been distorted due to overtightening, is there a corrective measure I can utilize to fix it? I have some ideas on how to do this but would like to know of more experienced remedies. Also, what kind of silicone is recommended?

Mucho appreciated, per usual.

wrench
 
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How deep is the gouge from the footpeg? If not too deep, you may be able to sand most of it out and then polish. A few battlescars add character don't you think?
 

Ron L

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Lay your outer cover on a flat surface and check for distortion. This can be "lapped" on a piece of flat glass. Place a straight edge against the face of the inner cover. If necessary it can also be lapped if necessary.

Now, with the inner cover attached to the crankcases check to see that the cover is shimmed at the fixing stud to there is no pressure attempting to bend the chaincase as the fixing nut is torqued down.

Follow Biker-man's procedure for sealing the O-ring and you should have a leak-proof primary chaincase.

The damage to the outer cover is likely due to a tip over slightly bending the footpeg mount. I like to trim the footpeg stud flush with the locknut to provide a little extra clearance. If there is still no room, I'd replace the footpeg mount or try adding some thin washers under the mount to move it away from the cover slightly.
 
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tpeever said:
A few battlescars add character don't you think?

Agreed, tpeever. The scar is too big to buff out, by a long way. Fair enough. It's part 'o the bike, for sure. Not trying to hide it's history, just want to make sure I allign the various parts to make her happy as she rifles down the road.

w/
 
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Ron L said:
Lay your outer cover on a flat surface and check for distortion. This can be "lapped" on a piece of flat glass. Place a straight edge against the face of the inner cover. If necessary it can also be lapped if necessary.

Now, with the inner cover attached to the crankcases check to see that the cover is shimmed at the fixing stud to there is no pressure attempting to bend the chaincase as the fixing nut is torqued down.

The damage to the outer cover is likely due to a tip over slightly bending the footpeg mount. I like to trim the footpeg stud flush with the locknut to provide a little extra clearance. If there is still no room, I'd replace the footpeg mount or try adding some thin washers under the mount to move it away from the cover slightly.

Thanks, Ron L, I definitely use your methods to check on the trueness of the covers.

I agree with your and L.A.B.'s assesment of the damage to the outer cover. The footpeg seemed in good condition, but there's no way to tell. I suspect a new footpeg was lashed on after an accident of some kind. I don't mind the scars, just want to make sure everything lines up properly. I suspect I'll add - as you suggest - some thin washers under the mount to take of any potential problem. A great idea.



Mucho thanks.

w/
 
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Hi Again - You asked what type of silicone I used. It is the tube type as sold in the hardware store for household use & installed with a caulking gun...

Be sure to use a NEW O Ring as well...
 
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Biker-man said:
Hi Again - You asked what type of silicone I used. It is the tube type as sold in the hardware store for household use & installed with a caulking gun...

Be sure to use a NEW O Ring as well...

Thanks Biker-man. I received my new O ring from Domiracer today (two days after I ordered it, btw.... good service from those chaps). I asked about the silicone exactly because of the answer you provided.... I wondered if it was the available house-hold stuff or I had to go through a specialty supplier. I owe you, for sure.

Cheers---

w/
 

MichaelB

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Check the inner ribs of the outer cover for cracks.
These will cause more distortion when tightening.
 

maylar

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I reuse the rubber seal unless it's so flattened that it has no compressibility. I use a film of clear RTV on the outer cover mating surface and also around the stud on the inside which contains oil that wants to leak around the fixing nut.

Do check that there are shim washers behind the inner chaincase to position it parallel to the engine cases. Telltale signs of that being screwey are that the left side swingarm pivot has dug a groove in the back of the chaincase. That will also reduce the drive chain clearance and sometimes the chain will dig into the chaincase too. Been there, done that.

Primary covers appear on eBay all the time. The battle scar yours has is not uncommon, but you can find really nice ones.

As for the rest... yep, looks like a Commando primary.
 
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maylar said:
I use a film of clear RTV on the outer cover mating surface and also around the stud on the inside which contains oil that wants to leak around the fixing nut.

Thanks maylar.

I think mine is leaking around the fixing nut as well. I'll definitely check out the RTV label as well....

Do check that there are shim washers behind the inner chaincase to position it parallel to the engine cases. Telltale signs of that being screwey are that the left side swingarm pivot has dug a groove in the back of the chaincase. That will also reduce the drive chain clearance and sometimes the chain will dig into the chaincase too. Been there, done that.

A nifty bit of advice. I'll try and look into this tomorrow. So far the raison d'etre of my not so NOS Norton :shock: seems to be the very embodiment of Murphy's Law. Errr....

Primary covers appear on eBay all the time. The battle scar yours has is not uncommon, but you can find really nice ones.

I've noticed that, too. I'll keep checking. The footrest does conceal most of the exterior damage, so it's all probably fine. And most likely, once I have it back on the road I'll be supplying my own battle scars as well --can't leave all the fun to previous owners, after all(!).

Cheers and thanks.

wrench
 
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