VW Speedshop wbx silencer cracks

[keith]

is there no stainless meshed section built into these. to allow for movement / expansion....?

[ghost123uk]

No Keith, there isn't.

From Ian's (Silverbullet) description of where and how his cracked makes me wonder about that bracket that holds the can to the pipes. That seems to my eyes to be a bad thing as it prevents the can moving to the right as the pipes heat up, perhaps causing the cracking of the left hand end plate (as the pipes expand). If I am right, then the common breaking of that bracket might be due to that stress and in fact may be a good thing. Ian has strengthened his bracket and perhaps that might make the end cap cracking issue worse?

[HarryMann]

A flex mesh joint a good idea though in itself can cause corrosion problems if not abs. top quality.
Quite often exhaust stainless but parts if flex joint not.

Made a s/s 2.5" AAZ custom exhaust 5 years ago with flex joint and copied JX silencer... no probs todate. Uses wrap around camclamp that allows plain sawn off butt joint ends to slide a bit.

=====

Smallcar '08 vintage 'stainless' header cracked to buggery, welded three times, finally gave up and ordered current model. Its 2kg heavier and a different grade. so fingers crossed...

Yes Andy,

Inherited one of these Smallcar Subaru systems from Syncro Pete. Not stainless..

Has been welded b4, partic at the acute 'V' junctions, so got the gas out and brazed it all up within an inch of its life. We shall see one day. ..

====

Stainless tends to have a lower expansion coefficient than other steels but expect it's a lot about grade, thickness and design detail...

Let's face it, the JX turbo manifold physically moves along the headface either side away from Cyl 3, due to the oversize holes on 1, 2 and 4.
Imagine the stresses when red hot if constrained!

Williams F1 at Didcot used to have two blokes building their exhaust manifolds. .
One did a left side and one a right taking a week or so...
then swapped the next week so each could make either in case of illness. That's how important it was, pretty well all they did I believe. ..

[silverbullet]

Good points raised all round, I know that I'm just moving the loads around to see what fails next. The can is pretty lightly made, I can't see how making them from even lighter gauge materials is going to help prevent embrittlement fracturing!
I just know that I will end up changing that cruddy little tab on the RH pipes for a slotted piece of s/s channel, to let it migrate through the heat cycle.
If the system had a flexi joint, then the can would need multiple restraints to prevent in resonating and generally flapping about all over the place!

PS Most exhausts are made from 304 grade (corrosion resistant, like cheap Ikea Chinese knives) because it's easier to form than the much tougher (and genuinely non-rusting) 316 grade (from which your Viners cutlery will be made) so there aren't many places that will make manifolds from 316, where the material would be of most benefit.

Case in point: the downpipes on my 2.6 have browned off nicely as far as the flexi, but from there on the rest of the system is still bright and shiney because it simply doesn't get as hot in service. Apart from one hanger weld failing due to poor design, that system has given no problems at all and it's done well over 20k.