Mk2A Binding Rear Brake?

 bike drum brakes have to be centralised and some play in the assembly is incorporated to allow this . It’s usual to slacken the axle nut on the brake side, apply the brake hard and tighten up while holding the brake on .

Hi Richard,  I'm thinking there is definately  something wrong in there, Can you post a photo of the shoes  ,or compare them to a known to be correct set. Also a picture of the brake cam , its possible to install it 180 degees out ,  It still works but with lost leverage. I'm not familiar with Commando's but it also sounds as if your speedo drive could be  dished /buckled , does it rub the alloy cover plate?.  A bit of open mind detective work for you !!. I would not be riding it till the issue sorted.  I can't think of a worse job than having to be  taking the rear wheel in and out.Consider putting those shoes ( Indian fakes?) to one side and buying some new from RGM ( gold woven linings) , If the old shoes turn out to be genuine get Villiers Services to reline for your spares box.

... as though when you tighten the RHS end of the spindle it's pulling everything across causing the binding. I would suggest a missing / wrong spacer. You do have the central tube spacer between the bearings fitted don't you? This would cause a similar problem if not in place.

The sprocket teeth have had it, whatever.

Hi Richard. In your last post you said that the PO hadn't fitted enough shims between the stub axle and the brake plate. I didnt know it was supposed to be shimmed out here. I changed my sprocket/drum recently. The old one was scored like yours but 10 times worse and when I reassembled the new one the bolt heads which hold the shoes on still caught on the rivets on the inside of the drum so I filled the heads down very slightly. Should I have put shims somewhere instead? I've never seen shims on any schematics. Have a look at the picture attached...what a mess!

Not being a Commando owner ,I don't know about shims. Its possible that the drum is dimensionally incorrect, there has been some poor pattern stuff. I know some of the linings on pattern shoes are completely useless despite "classic" branding, stick to RGM or similar.  I have had to file off the edges of shoes/linings for clearance to the back of drum. Chain alignment could be an issue too looking at wear pattern. Looks possible for shoes to be bearing on ledge worn in back of drum.

Sorry for nearly hijacking this thread but thanks Richard P for that much needed info and part numbers. Its always bugged me that something isn't as it should be, so it's great to know that this is how it is sometimes, especially as it's brakes,  and that there's a fix.  Cheers!

I have had my rear drum off and replaced shoes (RGM) recently on my Mk2A. 

I have reassembled everything, only to find the brake was reluctant to come off all the way. I have actually seldom used the rear brake as the pedal movement has always been too far in my opinion, so this has probably been the case for ever on this bike! I have since discovered that RGM list a return spring for the Commando brake pedal, which my bike has never had, which I have ordered and expect the problem to be cured - as a gentle lift of the brake pedal by hand is enough to get the brake arm back to its full release position - just as though the brake arm return spring isn't quite strong enough to do the job on its own? 

Whilst investigating this issue however I noticed that tightening the brake arm to its shaft ultimately tightened the arm against the brake stay arm - therefore preventing any motion of the arm? The problem is that the flats on the brake cam shaft don't appear to extend far enough to allow the arm to be tightened fully against the end of the flat portion without gripping the brake torque arm as well?

The brake cam was not disturbed when I changed the shoes, so it's been as is for the last 40 years to my sure knowledge. The manual lists a "bearing /spacer" between the swing arm and the brake backplate, but I only appear to have a chrome spacer? Could this be too long? 

... in the Commando Service Notes recommended cutting up a moped inner tube to act as backup / helper for the pedal return spring.

The main purpose of the spring for the brake pedal pivot was that in the event of a failure of the spring on the brake backplate the pedal spring would prevent the pedal dropping and acting as a pogo stick (edit - or perhaps I should have said like the pole of a pole vaulter) with potentially disastrous results. I seem to remember a police rider losing his life because of this happening.

Thank you for your comments. I also remember the brake pedal pogo stick story! There never being a moped rider around when you want one I have made do with a bunjee cord and the brake arm now returns to its stop. Success! As to the arm binding on the torque arm, I stripped the whole thing down again and found the large nut which attaches the tube to the backplate was loose to the extent that I got over a turn on the thing without difficulty! The result is a brake arm which no longer binds on the torque arm because the cam bolt can now extend far enough through the backplate. Now it all works perfectly. I can honestly say that in just over 40 years of ownership , this is only the second occasion I have felt the need to remove the rear drum - although this "occasion" was actually four times....Now it all works I shall certainly be using the rear brake more in future. Thanks again.

Pleased to hear that all is well but recommend getting the pedal safety spring.