The exhaust tube/header/pipe/whatever was welded and has been refitted with
utmost
care to ensure that there are no undue stresses imposed by misalignment or
"struggles" with the rest of the CKT exhaust system. CKT considerately includes
a sliding telescopic joint on #1 tube, which should be loosened and free to
slide while securing everything, then clamped up last.
The fracture was circumferential on #3 tube, at the level of the spring loop
welds
and I guess that is where the next fracture will occur. This is exactly where
the original fracture appeared and so I believe that two tubes doing the same
thing is a good basis for supposition. I've made a "containment device" by
using a jubilee clamp with a 1 cm wide strap, notching the strap halfway across
in two places to accommodate the tops of the spring loops and tightening it
to cover over most of the welded crack. This can be loosened periodically to
inspect for further cracking and hopefully will keep the fractured ends aligned
if the weld should fail.
Jubilee clamps can be really useful with exhaust tubes and I used a couple with
my original Europa exhaust to securely clamp short strips of steel with suitable
holes as replacement for welded loops which broke off.
My ruse for preventing springs from breaking is to cut a length of metal brake
tube to fit inside the spring, fold an 18" piece of locking wire in half and
pass
the folded end twice through the tube, leaving enough length to fit over a
spring anchor point, install the spring fully and then secure the two cut ends
of the locking wire through the spring loop.
Now take another 18" or so of locking wire and wrap it twice around the middles
of both springs either side of the exhaust tube, squeeze the springs in towards
the tube and twizzle the ends of the wire to keep the springs curving in
somewhat
towards the tube.
Finally run a line of red high temperature silicone down the lengths of both
springs
on the sides furthest away from the tube. Leave to cure for about 3 days
before starting the engine. More than 100 hours for me so far without repetition
of broken springs. My theory is that wrapping wire completely around the middles
of both springs changes the "harmonics" into something less destructive
and the silicone helps to dampen vibrations.
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