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1951 Manx rear brake repair


 Can anyone suggest the best repair method and company that could carry out a repair of the rear brake in the attached picture. It looks like in the past that a nut that holds the rear sprocket on has come loose and worn away the back of the casting and years of corrosion has done the rest.  Cracked casting


First suggestion is to contact Ken McIntosh at  who sells complete rear brakes for -51 to -63 Manxes.So probably he makes new brake plates. Though it looks a bit different to the one I have on my -59.

Second thought is that I'm not sure if yours is made of a magnesium or aluminium alloy. If magnesium, I would not attempt to weld in a 70 years old magnesium casting. They get quite fragile at that age. If aluminium it could be possible to machine the plate and make a part to be welded in place. But it will be very time consuming.

Third option is to simply cut away the damaged part and ride as it is. I believe (without knowing for certain) that the damaged part don't contribute much to the stiffness of the brake plate. Drawback could be if you ride it when raining more water can go in. But it could be possible to build it up to the original shape with something like JBweld.

Thanks for the great reply I have been wondering if it’s magnesium, I am trying to keep as much of the bike original as possible so with the broken section is very thin so your suggestion of the JBweld maybe the way I’ll go. 


Easy to check. Take some fine filings and set them alight. If you can't see anything apart from a big white spot in front of your eyes for the next ten minutes, it is magnesium.


But it won’t burn. Seems you only have around 30% of the original rim.  Why not loose it completely?  If you repair it you will end up with a material colour you will see the repair and addition.  Alternative to losing totally, replace it totally, with a machined alloy rim, welded on.

Its not a stressed element so providing the sprocket nuts are tight will last a long time.  Is it single or discrete twin leading shoe.   Value hike for twin may influence your decision.




A lot of material can be removed from a Manx brake. Done in the late sixties. Been ridden a lot after that. Also  a pic of the rear.



And rear. Modified so that the brake plate is floating.


In reply to by mikael_ridderstad


Thanks that's very interesting. I will consider possibly removing it. Attached is a photo of the me and the bike at I think Cadwell in the early 60s  


As Michael has shown, it does not detract if its not on there.  Is the machine being re-commissioned David.  You have shown us a "then" pic, what about a "now" one! with the pair of  you!


 Best regards



The bike is getting a long awaited makeover. Barry Strickland has done the engine and the wheels are about to sent off. Tank is painted. I have added a couple of photos and one of the my Inter which we have just about finished. The Inter has had quite a few modifications over the years. 


That is going to be some machine.  When you dress the brake plate up you should get it treated as you did the crankcase.  The inter didn’t appear in the pictures, .

Thank  you for sharing




That should blow the cobwebs away! Great stuff, bet you could tell a story or two about that one!   Thank you for brightening the day.

best regards




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