71 Brake Drum to Cush Hub- Pin Fix

T95 said:

Yes and it's certainly encouraging providing I can find someone confident to do the work !

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Just look for an old school welder with an oxy torch and some brazing rod.
Any small airfield will have an aircraft welder - just make sure he still has an oxy torch though, and will use it...

P.S. Nortons themselves had at least of the brake drum pins brazed in place, so this is not rocket science or voodoo magic or experimental wizardry.

As long as we are throwing all these welding terms and technologies into the mix, I need to add one more: silver soldering. If you could get the bores in the drum clean, and the pins clean, then silver solder would probably work very well. Braze will not travel down the pins very far, and welding is only penetration deep. Silver solder could be the strongest fix, if done properly. Note: this repair won't be successful if the original effort was brazed.

Stephen Hill
Victoria, BC

Strictly speaking, silver soldering is just a slightly lower temp version of brazing.
Intended for things that melt at lower temp than brazing is done at.
Or more delicate or thinner.

If the cast iron is good and hot, the braze should wick into any gaps - you know you have added enough braze when it drips out the other side....

Sheeze yoose guys - the drum is more steel than cast iron bridge or stove stuff. I've done, in, 4 drums paddles and just had a stick welder tack em deep enough bead could be ground back essentially flush so drum shoes just miss. Can leave some bead proud towards the axle. Tacks or stakes only has to resist mild torque shear not anything trying to suck em out of the drum. Real weakness I think is the factory cushions that chew up uneven on a single mild hwy ride. See pg 4 in below for flashy picture show

post125095.html?hilit=broken%20axle#p125095

Steve, steel bends, cast iron cracks. Usually.
You tested it on a grinder, to see what color spark it throws. ?

The trick with electric welding cast iron is that the weld can look perfectly good, but when you strength test it, it can just crack away and fall off.

For something thats spinning at wheel speed, and involved with the chain and rear braking system, you'd like to think its been done so it will hang together at all times .... !!

Rohan said:

Carbonfibre said:

TIG brazing is the easy way to fix this problem............clean it up and take it along to someone with a TIG set who should be able to do the work in about 15 minutes! No pre-heat required, and ideal way of repairing most things made out of cast iron.

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Don't know where you get your welding info from - and we've never seen anything you have welded - but came across this quote :-

"Welding cast iron using a tungsten inert gas (TIG) welder is possible, but will challenge even the most seasoned welder. "
Goes on to mention brittle brittle brittle....
i.e. Anything cast iron that has not been preheated will be extremely likely to go brittle, and crack.

Another quote about not preheating cast iron :-
Cast iron will obey the laws of physics, even if you don't know them
i.e. brittle brittle brittle

Cast iron is a bit prone to cracking anyway, even if it hasn't been welded.
Sounds like some owners here have met this, even with factory items.

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Next time you need to repair cast iron try TIG brazing as I suggested in my earlier post.............works very well indeed, and is fast and easy to do.

Rohan said:

Cheesy said:

In our friend carbons favor here he did say bronze welded.....

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No he didn't.
He said TIG brazed. With no preheat.

Brazing is NOT bronze, its brass.

And as that quote above says, cast iron goes brittle if its not preheated. And cooled out carefully.

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The filler material I use for TIG brazing is SIF No8 which is phosphor bronze, so I guess even though bronze "welding" and brazing are other than the filler materials used pretty much exactly the same process, TIG brazing using No 8 could also be termed bronze "welding".

Done hundreds of repair jobs using this method, and its worked well on pretty much everything from a turbo exhaust manifold, to very old and irreplaceable cast iron guttering from listed buildings!

Stephen Hill said:

As long as we are throwing all these welding terms and technologies into the mix, I need to add one more: silver soldering. If you could get the bores in the drum clean, and the pins clean, then silver solder would probably work very well. Braze will not travel down the pins very far, and welding is only penetration deep. Silver solder could be the strongest fix, if done properly. Note: this repair won't be successful if the original effort was brazed.

Stephen Hill
Victoria, BC

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Very good idea.............I would TIG braze one side of the pin, and then wick silver solder through from the other after the brazing has been done. Should result in a repair thats probably going to be stronger than the pin fixing was originally!

Carbonfibre said:

Next time you need to repair cast iron try TIG brazing as I suggested in my earlier post.............works very well indeed, and is fast and easy to do.

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Show us an example then.

When I went out on the net to read up on this, said it was tricky for even experienced welders.
And then talked about the need for preheating, or cracking will result.

As the quote said, you can ignore physics, but the cast iron won't...

Anything but cast iron may be a different story.
But that stuff cracks if the heat is not to its liking.
And brazing has to get hot enough for the brass to percolate into the iron's crystalline structure, so it can't be done too cold....

Carbonfibre said:

Very good idea.............I would TIG braze one side of the pin, and then wick silver solder through from the other after the brazing has been done. Should result in a repair thats probably going to be stronger than the pin fixing was originally!

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Why ??

If the brazing was done properly, the braze should wick through and flow out the other side.
If not, just turn it over and braze from the other side.

Mixing welding systems - is just weird advice ??

Rohan I only know simple welding 2-3 tack beads then grind to clear shoes has held up on the dozen I've found twisted or able to twist when tested. Drum must not be the same sort of brittle cast iron grade that needs special attention or I'd of broken teeth off instead of just wearing em so thin they just fan over then rub off to shallow nubins the chain just glides over uselessly. Muzzy Welding supply has special rod for the various hard to weld cast iron alloys and others. The cylinder barrels are for sure a more carbon rich brittle alloy that won't take well to stick welding.

If I had had to wait and take Trixies broken axle twisted drum paddles to a real shop I'd of missed out the best Norton trip I've had to date, which I didn't know I was going on till 12 hr before leaving. Truth is twisted paddles only chew up cushions faster by not bearing evenly on them. I've put hundreds of hard miles on twisted paddles before I discovered them. I expect most riders have too over the decades. It just ain't that big a deal I can tell but good practice in case it can cause some damage or danger.

I"ve got 2-3 old drums I use as mower trap weights, I'll go out and photo/video the sparks to diagnosis the alloy range.

Just went out and touched an 850 drum on the grinder. 1973, paddle type.
Sparked yellow, so its steel, so doesn't matter what you weld it with, will be fine.
If its cast iron though, it makes a difference - and some are.
test before electric welding...

Carbonfibre said:

The filler material I use for TIG brazing is SIF No8 which is phosphor bronze, so I guess even though bronze "welding" and brazing are other than the filler materials used pretty much exactly the same process, TIG brazing using No 8 could also be termed bronze "welding".

Done hundreds of repair jobs using this method, and its worked well on pretty much everything from a turbo exhaust manifold, to very old and irreplaceable cast iron guttering from listed buildings!

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Seems most of the discussion here is around the different names applied to brazing.
Brazing with brass (copper-zinc alloy) is the usual version. Which is like a hi-temp version of soldering.

Can't say I've taken note of welding with phosphor bronze, but alloys are called differently in different places. Does phosphor bronze flow, or build into fillets ?

As an aside, brazing with brass on manifolds and exhaust pipes is a real no-no, because of an odd reason - brass become really weak as it get hot, and will fail from lack of strength if there is then any movement - it fails within the crystalline structure of the iron.
Other alloys seem not to have this property, has something to do with the zinc ... ?

Say Huh, Norton drums come in more than one grade of metal, imagine that?
My 4 drums behaved like decent carbon steel and took some spark shots

Here's basic b/w spark burst chart
http://www.capeforge.com/Spark%20testing.html

Here's spark color chart
http://wearanswers.com/Instant-Answers/ ... ation.html

Here's the first most robust paddle weld I had done, only on lower half. Note the bead ain't rusted after years outside so ain't even close to drum alloy.


Here's drum sparks with flash


Came out well enough might not bother to post the video
Here's drum sparks w/o flash


Here's 30 yr old koehler cylinder

A more detailed text labeled photo pointer
http://www.searchsteel.com/2011/04/spar ... teels.html

Here we go again - what do you mean by 'carbon steel', Steve ?

Wiki has an explanation of carbon steels - a very broad suhject.
http://en.wikipedia.org/wiki/Carbon_steel

Note in para 3
"a higher carbon content reduces weldability"
which means we are getting closer to cast iron. ?

Watch those Indian-made rear brake drums /sprockets ?
Cast iron is a lot easier and cheaper to cast, and machine, than steel.
It could also be interesting to know if Nortons used steel, or malleable cast iron....

Rohan said:

Carbonfibre said:

Next time you need to repair cast iron try TIG brazing as I suggested in my earlier post.............works very well indeed, and is fast and easy to do.

Click to expand...

Show us an example then.

When I went out on the net to read up on this, said it was tricky for even experienced welders.
And then talked about the need for preheating, or cracking will result.

As the quote said, you can ignore physics, but the cast iron won't...

Anything but cast iron may be a different story.
But that stuff cracks if the heat is not to its liking.
And brazing has to get hot enough for the brass to percolate into the iron's crystalline structure, so it can't be done too cold....

Click to expand...

If you cant actually TIG braze yourself, it seems strange that you have so much to say about something you have only read about on the net? The process is actually far easier than TIG welding, and having carried out hundreds of repairs in this way, I have yet to have any problems with cracking, as heat input is so low these are easily avoided.

Rohan said:

Carbonfibre said:

Very good idea.............I would TIG braze one side of the pin, and then wick silver solder through from the other after the brazing has been done. Should result in a repair thats probably going to be stronger than the pin fixing was originally!

Click to expand...

Why ??

If the brazing was done properly, the braze should wick through and flow out the other side.
If not, just turn it over and braze from the other side.

Mixing welding systems - is just weird advice ??

Click to expand...

TIG brazing is a low heat micro fusion process, and the filler material will not wick into the joint like gas brazing, which will mean far more heat and possible problems with cracking/distortion.

Other than powder welding, TIG brazing is the fastest and most effective way of repairing cast iron parts, and is much easier than TIG welding.

Think I'll just buy new ones for $100. no worn sprocket, no worn brake brake drum, no loose paddles, well not for a while anyway.

Carbonfibre said:

If you cant actually TIG braze yourself, it seems strange that you have so much to say about something you have only read about on the net? The process is actually far easier than TIG welding, and having carried out hundreds of repairs in this way, I have yet to have any problems with cracking, as heat input is so low these are easily avoided.

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I can TIG weld.
I can't even FIND anything meaningful on the net about Tig brazing of cast iron.
Except with mention of extensive preheating.

Have you ever had such a weld strength tested ?
Its easy to make electric welds on cast iron look pretty - but they fall off when tested !

Show us a pic of an example.
Show an example on the net of such a process even.

Jist call me Skeptical....