Exhaust work questions - Mig

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You guys that do typical exhaust like replacing OEM rust outs on a daily driver, or work truck:1. I have read Mig is the preferred process, quessing mainly for speed, please expand on this.2. My focus is not on cheapy repairs on a junker to last a year or two, or custom all stainless performance. I realize most vehicles will be beyond 5 to 8 or more years by the time a muffler fails, but a lot of 10 year old middle priced vehicles with around 100k mi can easily still be worth $7-10k, and maybe a second owner plans on keeping it and expects the replaced muffler or exhaust piping to last. That would be me.So, do you typically use SS wire and tri-mix gas on these, even if the replacement parts are aluminized type and not SS? I know you need to dress off the galv. at the joints. Also, I think the existing good sections are SS.My perspective on this is will typical steel ER70S-2 wire just rust out quickly? Sorry for the long post, but I wanted to frame it towards my specific concerns.Last edited by jtcnj; 12-01-2012 at 07:19 AM.Lincoln AC/DC 225/125 and WP17. 75A AC is for pipe thawing!HH 140 - new addtion 9/2012.I didn't agree, but hoped for Hope and Change.I got change for myself and my family: for the worse.This is the reality of: Barackalypse Now. Again.
Reply:For run of the mill work, mig is great.  Go with aluminized piping.  Lasts a VERY long time.  I have not logged any stainless, other than mild steel or aluminized tubing to 409 stainless mufflers and cats.  Works just fine with the wire you mentioned.  Have not messed with welding on galv much, but when I do, I try to remove the coating at the weld.  Consider proper PPE when welding galvanized.Jet 17.5" Drill Press1942 South Bend 16x84 Lathe1980s Miller 320A / BP --- 2013 Power Mig 2562012 Jet 7x12 Horizontal BandsawVictor O/A Setup
Reply:Depends on whats there. I've never done a full stainless exhaust, but if I did (especially if I was getting paid to do it) I would probably use a stainless filler.But like rabid, if I'm welding 409ss or mild steel, I just use 70s2. If I really care I may hit the weld and cleaned metal with exhaust paint or cold galvanize.IW Local 580 NY, NY
Reply:For an old junker car, why would you spend money on a SS exhaust?  Why not use less expen$$$ive galvanized steel exhaust?  Buy an exhaust from your local AutoZone, grind off the zinc galvanized coating  at the weld joint and use the MIG with the wire you described.  Simple. Unless you want to throw money away on that junker car you have, forget the SS.  That new galvanized pipe should outlast the remaining "life" of that car.  When that second exhaust pipe fails some day, it'll probably be time for a new car anyway, don't you think?Last edited by SuperArc; 12-01-2012 at 02:18 PM.Lincoln Power Mig 216Lincoln AC/DC-225/125Miller  625 X-Treme PlasmaMiller 211 Forney 95FI-A 301HF 91110Victor Journeyman O/PMilwaukee DaytonMakita  Baileigh NRA Life Member
Reply:Here's a thread:http://weldingweb.com/vbb/showthread.php?t=20739__________________
Reply:Originally Posted by SuperArcFor an old junker car, why would you spend money on a SS exhaust?  Why not use less expen$$$ive galvanized steel exhaust?  Buy an exhaust from your local AutoZone, grind off the zinc galvanized coating  at the weld joint and use the MIG with the wire you described.  Simple.