OzVMX Forum

Clubroom => Tech Talk => Topic started by: Bitten on August 16, 2012, 05:20:21 pm

Title: Can this be fixed?
Post by: Bitten on August 16, 2012, 05:20:21 pm

I have found this crack on the end of my brake drum

In the short term can this be welded and machined?

(http://i1076.photobucket.com/albums/w449/justinbowtell1/2ff6a45c.jpg)

Title: Re: Can this be fixed?
Post by: mick25 on August 16, 2012, 05:47:58 pm

You will find the shoes dont make contact with the out side edge where it is broken.
I have a few yamaha ones that have broke in the same spot but you can see where the shoes rub, and they dont rub that far out,
I would just leave it be

Title: Re: Can this be fixed?
Post by: Bitten on August 16, 2012, 07:56:16 pm

Thanks Mick

I was more worried that as it is on the thin lip than sits inside the brake backing plates just as thin matching groove it may catch and rip apart or worse still throw me over the handle bars!

This is all tied into my earlier post re the tight fitting brake shoes so I will take the lot off to Burt Bros as suggested and see if they can do anything as I dearly want all to be in fine fettle for my first Classic Dirt

Cheers

Title: Re: Can this be fixed?
Post by: RMJJ on August 17, 2012, 07:38:56 am

That an RM straight pull spoke hub, reasonably common fault.
My front hub is like that and runs fine.
If I was you I'd break that bit off and carry on regardless.
It's part of the cast iron liner, not the alloy hub so will be safe.
As said above, the shoes don't rub on hat bit so it's not really of any use and won't affect braking if removed.

Title: Re: Can this be fixed?
Post by: RMJJ on August 17, 2012, 07:42:27 am

Oh and the thin lip as you call it that sits inside the backing plate is only there due to lack of wear from the shoes. When brand new the hub lining is "that thick" all the way across. It's not a "thin lip" it's the correct thickness of the lining, the rest has worn thin.
Just break it off to avoid a jam up. It'll be fine

Title: Re: Can this be fixed?
Post by: RMJJ on August 17, 2012, 07:46:46 am

Actually reading it again I think I see what you mean by thin lip inside he backing plate. That's just to stop water ingress. In the real world it'll make no difference whatsoever if a bit is missing.

Title: Re: Can this be fixed?
Post by: GMC on August 17, 2012, 08:24:24 am

I agree, brake drums are usually made from cast iron as it has good wear & heat characteristics but it is unweldable in this situation.
Cast Iron can be welded but it is fiddly to do, it will be harder to do with aluminium  on the opposite side of the weld and the nickel rods required to weld it with will make a hard spot that won’t wear the same as the rest so is unsuitable for a brake drum.

The broken part seems from the photo’s to be superficial to your needs so I would also say break the piece out, you don’t want it coming out by itself while your riding it, the results wouldn’t be nice.
You may even damage the pipe. :)
Be sure to chamfer all edges around the break

Title: Re: Can this be fixed?
Post by: Bitten on August 17, 2012, 10:20:50 am

Thanks JJ & Geoff for your advice

I can sleep a bit easier now!

Cheers