Header Pipe Not Secure

I've got a bead on new, never installed left side pipe marked "Toga" from someone in Toronto...$30 but he's hesistant to package and post it. Trying to persuad him....
Also got some requests out to local welders for quotes.
 
ludwig said:
Why new? Fix it ,or have it fixed. Brazing is better than welding.
Click to expand...
Exactly... brazed this up a few years ago... same type crack...still good as....
 

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My master welder teacher at Site 3 and Humber college tech school ( Toronto ) , brazed up a job just like that for $ 50 Cdn . He made a hardwood jig/with table clamps to hold the 2 pieces in position after rigorous cleaning . He said it would be braze , not welding .
 
As mentioned above, brazing is one method of repair.

Other methods can be successfully done as well. While on the way to the "End of the World INOC rally" 2012 in Vermont, my pipe broke clean off. (giving riding lessons to a hog rider).
Stopped at a good friends house, turned his little Lincoln MIG down as cold as it would go, .023" wire, and stitched up the pipe. Too hot to sustain a bead, a series of quick trigger starts allowed the repair.

1686391111779.png


I would have TIG welded it, had I been near home, access to the machine.

The OP's break is very much the result of the engineering fail to rubber mount the mufflers.


Before the naysayers converge, remember: "if you don't ride 'em they don't break."
 
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Long term testing can now claim success, 10 years.

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Engineering compromises leading to exhaust threads stripped (2012)

Best I can see is, the exhaust threads being a problem area, is the result of multiple engineering EVOLUTION compromises. In the beginning, the head was cast iron and the threaded attachments probably worked just fine. Then the thread (head) material changed to softer aluminum... and they...
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baz said:
I've tigged them up before using stainless rods
But brazing would be best
Click to expand...
Brazing, on a thinwall tubing joint has the advantage of distributing the forces over a much broader area of the thin material, which is a good joint design in some cases.

The OP's pipe, and most I've seen are MIG'ed, for obvious production reasons.
I contend that brazing will not stop header pipes from cracking altogether, and, eventually, they will crack adjacent the joint.

JMWO
 
The OP's pipe failed in the middle of the weld, which, appears to be a sound, production, MIG weld on to the much thicker flanged collar.
Ongoing fatigue is the failure mode.
7AE99287-06C4-4C27-A49A-E4A2AB018690.jpeg
 
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These pipes came to me as a used set, unknown history, put on my bike about 2.5yrs ago I'd guesstimate. Replaced the set of balanced pipes, presumably originals, which had the common cracks at the branch weld.
Been running with pretty heavy vibration issues for past year with hockey puck rear isos installed. Resolved that just two was ago and now find crack, but could have been there for some time.
 
concours said:
The OP's break is very much the result of the engineering fail to rubber mount the mufflers.

Before the naysayers converge, remember: "if you don't ride 'em they don't break."
Click to expand...

Failure to rubber mount? You mean something other than the iso bobbins?
 
Tornado said:
Failure to rubber mount? You mean something other than the iso bobbins?
Click to expand...
Not positive what concours meant, but the rubber mounts aren't really enough and there's little that can be done about it. If the head moves 1/2" the back end of the pipe must move MUCH more and by the time you get to the rubber mounts - it's a LOT! I'm guessing that's probably why some don't use a clamp at the pipe/muffler junction.
 
marshg246 said:
Not positive what concours meant, but the rubber mounts aren't really enough and there's little that can be done about it. If the head moves 1/2" the back end of the pipe must move MUCH more and by the time you get to the rubber mounts - it's a LOT! I'm guessing that's probably why some don't use a clamp at the pipe/muffler junction.
Click to expand...
After some thought, I think he means the engineering fail of using rubber mounts to the fixed frame, instead of something solid, perhaps affixed to the moving engine at more than just header flange.
 
Tornado said:
After some thought, I think he means the engineering fail of using rubber mounts to the fixed frame, instead of something solid, perhaps affixed to the moving engine at more than just header flange.
Click to expand...
That too. Look at a Triumph. Just before the bend backwards there is a bracket to the engine even though the engine is not rubber mounted and the pipe (on most) is clamped over a stub pipe in the head. Not sure how you would accomplish anything like that on a Commando. However, the stub pipe with Triumph type clamps and pipes to match might stop cracking and damaging the head's threads - just a random thought.
 
marshg246 said:
That too. Look at a Triumph. Just before the bend backwards there is a bracket to the engine even though the engine is not rubber mounted and the pipe (on most) is clamped over a stub pipe in the head. Not sure how you would accomplish anything like that on a Commando. However, the stub pipe with Triumph type clamps and pipes to match might stop cracking and damaging the head's threads - just a random thought.
Click to expand...
When I had stainless downpipes on my commando they were always cracking at the exhaust rose
So I put an extra mount off of the front isolastic bracket similar to triumphs setup
It made no difference they still cracked
So I gave up with that idea
Then I fitted extra mounts off of the gearbox cradle
This made them last longer before cracking
 
baz said:
When I had stainless downpipes on my commando they were always cracking at the exhaust rose
So I put an extra mount off of the front isolastic bracket similar to triumphs setup
It made no difference they still cracked
So I gave up with that idea
Then I fitted extra mounts off of the gearbox cradle
This made them last longer before cracking
Click to expand...
Hi Baz, do you know if the stsinless header flange part of yours was just tig welded on the end i:e the bit that seals against the head , and or if it was welded like the one shown , this is were its nice to back purge with argon which will remove the sugaring and improve the strength, Cheers.
 
Shelby-Right said:
Hi Baz, do you know if the stsinless header flange part of yours was just tig welded on the end i:e the bit that seals against the head , and or if it was welded like the one shown , this is were its nice to back purge with argon which will remove the sugaring and improve the strength, Cheers.
Click to expand...
Purge welding is a must for stainless exhaust systems
 

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