Amazon: Exhaust advice please

[woodman]

Hello

My exhaust has been on borrowed time for a while and it finally gave up tonight. I'm planning on keeping the car for some years so I'm interested in a stainless system if the price is OK. However I notice that the stainless systems advertised by Brookhouse say they're not compatible with the automatic transmission. I'm going to ring Simon tomorrow for his advice, but what's yours? Is this just to do with how the pipe is bracketed onto the back of the transmission, or is the pipe routing different? What's the best bet? I don't want a big Subaru-type noise, but a little more exhaust noise in exchange for a bit better oomph might be worth considering. Do the mild steel systems last long enough not to be worth worrying about stainless?

Cheers.

[tom-madbiker]

stainless is good but i does tend to stress crack easily i made mine out of mild steel similar to the ruddspeed system but i havent tried it on the road yet

[Burdekin]

Originally Posted by tom-madbiker

stainless is good but i does tend to stress crack easily i made mine out of mild steel similar to the ruddspeed system but i havent tried it on the road yet

+1 to that, especially if it's something like 316 it won't like the salt in winter. Best to check what grade of stainless they will be using first as some are more resistant but also you'll only get issues at welds exposed to salt really. If you paint the welds and if the paint stays on you shouldn't have a problem also with stress corrosion cracking.

[tom-madbiker]

i thought that 316 was ok with salt but 304 was not so good exhausts are usually made with 304 as it engineering grade not food grade and it bends easier ect

[222s]

316 is ok with salt - that's the marine grade.

[Burdekin]

We've had cracking offshore with 316, hence why we use duplex st/st now and not 316.

[222s]

Sounds like the issue there is that 316 isn't high tensile, rather than one of corrosion resistance, or am I misunderstanding something?

[Derek UK]

The front pipe used with the auto needs a small offset/kink to clear the levers on the side of the BW35. The auto was only available here for a couple of years but those straddled the change from single to twin downpipe manifolds. I don't know if both front pipes have to be different to the manual box ones to clear the box.

[Burdekin]

No it's corrosion resistance. 316 is probably slightly better than 304 but still not good in a marine environment. It doesn't rust like mild steel, it just corrodes in another way given the right environment. SCC will occur at higher stress areas like welds that haven't been pre- heat treated properly, it is also susceptible to pitting. The operating temperature is also a critical factor. So it will most likely to occur at welds, so by painting you stop the chlorides attacking the metal, so if the welds on the exhaust are painted you shouldn't have an issue. We paint all new duplex st/st even and it has considerably higher resistance to corrosion than 316.

[222s]

Strange - I've seen plenty of marine grade 316 s/s on yachts (fittings, guardrails etc) and even stuff that is over 30 years old, and never cleaned is still fine. I guess you guys are giving it a much harder life!!!