Rear drum noise

Help! Just fitted a new rear drum/sprocket as the drive lugs were rotating. Renewed all the dummy axle bearing and seals etc, bit of a pain. Back wheel is now in and no rotational play which I am sure will cure the second grade snatch however there is a light knocking sound once eveyr rotation of the wheel from the drum. It disappears when the wheel is slackened off. Could this be one of the drive lugs clashing with the brake shoes? They send more proud than the old ones. I don't know if to ride and ignore or pull apart. Any ideas?

I've got the same problem recently. Eventually I found that the depth of the new brake drum was 1 mm. less than the old one :shock: so the brake shoes made indeed contact with the lugs. I could solve it by adding a 1 mm. thick washer.

If you look in the parts books exploded view it shows a washer and the quanity is A/R meaning "As required".
Some need one and others don't.

Thanks Guido I will do that. RGM sent me all the parts but there was only one. I guess it's the one between the dummy axle as it enters the drum.

So I call RGM today and get Roger on the phone who was very helpful. It's usually the nut heads fouling the three drive pins. I decided not to order any washers and grind the nuts down. I work from home Mondays so midday I stripped it and ground the nuts down where I could see it had been fouling the drive pins. Put it back together confident that it's fixed. The noise was still there but only just audible. Half past five tonight I take it for a test ride. Guess what? 200 yards later the static noise is actually louder, shock horror. What a plonker, guess that's the BSc &PhD in engineering. Back to the garage let's try again. Stripped it even quicker this time. Getting a fair bit off the nuts and back together again full of confidence. Noise still there. Will order more washers tomorrow but away for three days now so it looks like I am going to the Manx on the Velocette Venom..
Isn't it wonderful though when you renew all the back end sprockets and all dummy axle parts to find a problem that wasn't there before..Not

Similar problem here with new drum. Mine came from Old Brits. Not having a extra washer at hand I eased the heads of the bolts. The noise
was less. Better yet you really dont hear it at speed with the new AN silencers thundering away. They tame the tappet clatter too.
Loud pipes don't save lives but they make you feel better.

How much do we hate that crapulous rear drum and hub setup? If it wasnt so light Id get rid of it.
Paging Ludwig.....

Yes it's just a bar steward having to take the chain off to get the clearance to get the sprocket off and under the chain guard. Then rethreading the chain which is awkward with the chain guard on but I have it sussed now; just nesed a well practised limbo dance under the rear number plate to carefully thread chain over sprocket before the wheel goes back in.

As previously mentioned, in the parts book for rear wheel, part #21 is the 'as required' washer that sits on the dummy axle to give clearance for the back plate.
You can check for clearance/grating while on the bench.
Place the complete brake drum/sprocket with dummy axle assembled on the bench, then place assembled back plate with shoes over the dummy axle and spin it.
Should not be any grating sound. Check for metal on metal wear marks.
If making a rubbing noise add another washer and try again.

When you get it all back together on the bike, be sure to centralize the brake pads in the drum when tightening the axle nut as described in the manual.

Good luck.