Inner Chaincase Sealing Disc Failure

Dellis

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Riding a long last week my bike started to make a strange catching noise, I pulled over and it stopped so I pulled off and it came back, I pulled over and investigate. Rotating the rear wheel made a rubbing noise coming from the back of the gearbox. I got down and poked my head underneath to try and see what was going on , it's not easy to sse but I could see something between the front sprocket and the inner primary but couldn't make out what it was so common sense took over and I jumped on the back of my pals bike to go and get my trailer.

So yesterday I pilled the primary apart and the issue was that the spot welds on the sealing disc had failed and the half between the primary and front sprocket had been chewed up by the chain. Looking on both RGM and Andover the discs are unavailable however I found them at Norvil and have ordered a replacement. Only issue is they are spot welded and I don't have access to a spot welder so I've decided to drill four holes in one of the plates where the spot welds would be located, clamp them together (I've turned a couple of alloy bits to achieve this today), and then mig weld the two halves together. This will be next weekend and I'll update on the results after my efforts.

Dave
 

texasSlick

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Or 6 little screws and nuts and a little locktite work too.
Little screws, nuts, and loctite is how I did mine. If I should ever have to remove my inner primary cover again, I will investigate installing a lip seal between the disks. I have stopped all the primary case leaks except a small weep past the discs along the transmission shaft.

While you are in there, you might consider the modification between the discs which I did to suppress oil leaks ....https://www.accessnorton.com/NortonCommando/how-to-make-the-atlas-dominator-primary-oil-tight.26860/

Slick
 
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You could also make a spot welder out of an old microwave oven... :cool: I think I spent less than $50. to make it. It turns 120volt/15 amps into ~ 40volts/800amps (I forgot the exact figures) You could find the instructions to make it on Youtube if you search. I made it after I finished making the capacitor powered spot welder I needed to rebuild NiCd battery packs.

microwave spot welder1.jpg
 

concours

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Drill one half with 1/8” holes plug weld using whatever welder you have access to. (MIG, TIG, gas weld, braze) doesn’t take much.

I’d be looking for WHY that seperated...
 

olympus

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Drill & screw the two halves together with 6 M3 screws/ nuts with a dob of Loctite... easy peasy task to fit and compress the felt washer
 

Dellis

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Drill one half with 1/8” holes plug weld using whatever welder you have access to. (MIG, TIG, gas weld, braze) doesn’t take much.

I’d be looking for WHY that seperated...
I've already looked at the two halves and I have to say I'm amazed they held together for so long. The inner disc has a 'slinger' fitted and the weld had penetrated through the 'slinger' and the inner disc but you can only just see the slightest mark on the outer disc where the weld should have penetrated so my conclusion is that the initial spot weld had insufficient penetration to properly weld the three layers together.

Dave
Little screws, nuts, and loctite is how I did mine. If I should ever have to remove my inner primary cover again, I will investigate installing a lip seal between the disks. I have stopped all the primary case leaks except a small weep past the discs along the transmission shaft.

While you are in there, you might consider the modification between the discs which I did to suppress oil leaks ....https://www.accessnorton.com/NortonCommando/how-to-make-the-atlas-dominator-primary-oil-tight.26860/

Slick
To be honest mine doesn't leak from the back of the primary so I will reassemble as it subject to fixing the plates together.

Dave
 

Dellis

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Thanks for all the replies. Food for thought with the nuts and bolts ideas, I did think about this but thought the weld might be a better job although with nuts and bolts you can seperate the two halves but I'm not sure why I'd want to... Thoughts?

Dave
 

texasSlick

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Thanks for all the replies. Food for thought with the nuts and bolts ideas, I did think about this but thought the weld might be a better job although with nuts and bolts you can seperate the two halves but I'm not sure why I'd want to... Thoughts?

Dave
To replace the felt washer at some future time?

Slick
 
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I have the infamous pressed steel dommie chain case with twin washers and felt. Not sure if it's quite the same on a commando but I drilled and soft rivetted mine. Next change, drill out rivets and renew. Maybe different for you big boys. !!
 

Dellis

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To replace the felt washer at some future time?

Slick
I've just been out to have a look and with the 'slinger' attached then the bolts heads would have to be tiny, as tiny as 8 ba, and i'm not confident in that as a fix so I've decided to stick to plan a and weld them together. I've changed the felt seal before when the plates we attached to one another, it would be easier if the plates could be separated but it's not that difficult when they're together.

Dave
 

Dellis

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You could also make a spot welder out of an old microwave oven... :cool: I think I spent less than $50. to make it. It turns 120volt/15 amps into ~ 40volts/800amps (I forgot the exact figures) You could find the instructions to make it on Youtube if you search. I made it after I finished making the capacitor powered spot welder I needed to rebuild NiCd battery packs.

View attachment 13370
I do like that.

Dave
 
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I used pop rivets and then sealed the holes. Also I shimmed the case for better alignment
 

Dellis

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Parts arrived and as I said decided on welding the plates which is what I did, all is now back together.

Dave
 

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