AngryCorvair (Forum Supporter)
AngryCorvair (Forum Supporter) GRM+ Memberand MegaDork
4/10/22 1:58 p.m.

Looking at exhaust coupling methods, thinking about V-bands versus slip fits. All the V band kits I see are 304 stainless. Looks like I can join 304 to mild with 309 filler. Questions:

  • is that correct?
  • any other tips?
  • are there mild V bands I should look at instead?
Rodan
Rodan SuperDork
4/10/22 2:11 p.m.

You can get mild steel V band flanges of Amazon (and probably other places).  I've used these with good results:

3" mild steel V band

I've also just mig welded stainless resonators to mild steel tubing with normal wire... haven't had one come apart yet.

frenchyd
frenchyd MegaDork
4/10/22 3:02 p.m.

Thank you for asking and answering. .  It's a question I'm not ready for yet but soon.   Just know that there are always people reading these and answers may come at any time.  

Honsch
Honsch Reader
4/11/22 12:07 a.m.

If you're using a TIG welder you want 309L filler rod.

Here's a tip: When welding the vband on, have it clamped to the mating half too if you can.  It will help keep it from warping too much, and let it cool while clamped.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
4/11/22 8:25 a.m.

I just buzz 'em on with the MIG and regular wire.

 

I weld stainless to stainless with regular wire, too! Never an issue longevity-wise.

Paul_VR6 (Forum Supporter)
Paul_VR6 (Forum Supporter) SuperDork
4/11/22 8:49 a.m.

I'm generally agreeing with the above. If you want "the best" use some SS rods (I always have 316 around) with the 309L being the technically correct answer if you are trying to pass a test.

AngryCorvair (Forum Supporter)
AngryCorvair (Forum Supporter) GRM+ Memberand MegaDork
4/11/22 10:07 a.m.

thanks for the feedback, y'all.  this is a challenge car, not trying to pass any structural tests, but trying to do it right since i'm still learning about welding etc.

Wicked93gs
Wicked93gs Reader
4/11/22 12:45 p.m.

I used normal MIG wire to weld some SS v-bands to mild steel tubing not too long ago..no issues, but then I am not using them as turbo hot pipes or anything, just regular exhaust, and temp exhaust at that as I try different exhaust components. My permanent setup will be all stainless once I get the sound I want.(these are just component mix-and-match pieces that allow me to try different cat/resonator/muffler combinations)

obsolete
obsolete GRM+ Memberand HalfDork
4/11/22 2:04 p.m.
Rodan said:

You can get mild steel V band flanges of Amazon (and probably other places).  I've used these with good results:
3" mild steel V band
I've also just mig welded stainless resonators to mild steel tubing with normal wire... haven't had one come apart yet.

Are those zinc-plated? Every time I try to buy mild steel V-bands, they show up zinc-plated, which just sucks. Gotta grind the zinc off before welding, then most of the remaining zinc peels and flakes off from the welding heat.

I've had good luck MIGing mild to 409 stainless, but I've always been afraid to try 300 series because of the different expansion rates. Maybe I'm just being a Bob Costas.

RacetruckRon
RacetruckRon GRM+ Memberand Dork
4/11/22 2:06 p.m.

You could weld it together with any ferrous filler rod but 308 or 309 (something with some Nickel in it) would be preferred.  Clamp the mating Vband half to the one you are welding to act as a heatsink and to minimize warping. 

A trick I learned from Toyman is to apply copper anti seize to the clamp threads and mating faces when you do final assembly on the car.  I have never had an issue with stuck Vbands or galled threads after doing this and I do all of my assembly and disassembly with a Milwaukee 3/8 impact.

Honsch
Honsch Reader
4/11/22 9:06 p.m.
obsolete said:

Are those zinc-plated? Every time I try to buy mild steel V-bands, they show up zinc-plated, which just sucks. Gotta grind the zinc off before welding, then most of the remaining zinc peels and flakes off from the welding heat.

You can remove zinc plating with phosphoric acid rust converter.

stukndapast
stukndapast Reader
4/11/22 10:54 p.m.

I have used those exact Evil Energy v-band rings welded to cleaned aluminized pipe welded with regular MIG wire without any problem.  Evil Energy also has SS versions of the v-band which I have also MIG welded to the cleaned aluminized pipe with very similar results.  I use both on a turbo exhaust system.  Note, however, that the SS v-band and the mild steel v-band from Evil Energy DO NOT mate together.  There are differences in the way the rings interlock so you cannot mix and match.

BA5
BA5 GRM+ Memberand Reader
4/11/22 11:37 p.m.

Sometimes I like to start this fight:

99% of welding details don't matter unless you're building pressure vessels, civil structures, or aircraft.

So long as it's actually melted together it'll work for anything else.

bigeyedfish
bigeyedfish Reader
4/12/22 12:12 p.m.
BA5 said:

Sometimes I like to start this fight:

99% of welding details don't matter unless you're building pressure vessels, civil structures, or aircraft.

So long as it's actually melted together it'll work for anything else.

I was using the tractor to drag some logs around this weekend and was really glad I didn't take any shortcuts when I welded up the bucket and chain bites.  Good design subjects the welds to as little stress as possible, but sometimes the details really do matter.

That said, I agree with you for the most part.  I wouldn't worry about mixing and matching mild and stainless on an exhaust for my own vehicle, but I wouldn't mismatch materials on a customer's project.

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