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Old 03-10-2018, 06:01 AM   #1
Hyper
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Default MIG v-band flange possible?

I am sick and tired of the stupid 2 bolt flat flanges in the DP to MD and MD to muffler connections, which always leak

since I jerk the DP on an off quite often, I am thinking about cutting the damm 2 bolt flange off, and welding a v band with lip
since its under the car and beauty is not a thing there, I don't feel like spending an arm and a leg on TIG welding services, and instead can have MIG welded it for free, question is - is this acceptable?
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Old 03-10-2018, 06:11 AM   #2
jvangelder
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I mig'd vband flanges on a previous car, a turbo RX7 and everything was fine for the 10k miles i put on the car.
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Old 03-10-2018, 01:22 PM   #3
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Theoretically itís possible for sure but you have to be very careful to not over heat and warp the flanges.
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Old 04-16-2018, 02:39 AM   #4
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Theres an exhaust shop near me that MIG welds vband exhausts all of the time. Post some pics if you end up doing it!
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Old 04-16-2018, 06:56 AM   #5
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Quote:
Originally Posted by I--RIDE--BIKES View Post
Theoretically itís possible for sure but you have to be very careful to not over heat and warp the flanges.
migs put way less heat into a part than tigging does
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Old 04-24-2018, 08:22 PM   #6
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As one who has ruined a couple vband flanges in the past year or so with a MIG... This is doable with a few caveats.

- Are we talking stainless or mild steel? MIG with stainless done right takes expensive gas. Even with the good gas, all of my attempts ended up not being completely air tight, which isn't overly important after the turbo, but something to be aware of.

- I can't say it enough, take your time and be really careful with your heat, they really like to warp, frequently rather subtly such that you might not even notice the warping until you have it all together but can't get your connection to stop leaking without adding gaskets (I've had acceptable luck with custom copper gaskets from a guy on ebay) and such.

- Protect your flanges from spatter really well. Given the close proximity of the flange lip to the joint and the size of most MIG nozzles, this can be tricky to do well without obstructing your access to the joint. My one attempt with MIG that didn't warp the flange got a couple spatter bits on the lip that I had to grind off and resulted in a couple of spots that the clamp doesn't slide as evenly on.

Now that I have both MIG and TIG, I'll never try MIG on these again.

In short, as long as it's all after the turbo, take your time and be careful, it's not ideal, but it's most definitely doable.
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Old 04-26-2018, 11:44 AM   #7
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Quote:
Originally Posted by rtv900 View Post
migs put way less heat into a part than tigging does
unless you run a pulser! i recently added a PC-300 to our Syncrowave 250 and am beyond impressed with the results. it reduces the heat affected zone tig-nificantly!
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Old 04-26-2018, 11:55 AM   #8
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Yes you can MIG it. I've never had good luck MIG welding stainless with tri-mix. It kept sugaring up due to not having enough post flow.
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Old 04-26-2018, 11:56 AM   #9
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What about:
-clamping mating flanges tightly together to remove some of the heat while welding
-making several small tacks around the circumference before completing the weld

If it's not for beauty, seems like you could do short sections, maybe even rotate to the opposite side, instead of one continous bead
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Old 06-30-2018, 10:06 PM   #10
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Default MIG on V band

Since this is stainless and electricity through stainless messes with the alloy alot you need the proper gas flow. many pipe welders use a plug system to close the pipe and then fill them with a low pressure flow of Argon. spend the time looking for a guy with a TIG system and get it done right.
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Old 07-05-2018, 01:54 PM   #11
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Quote:
Originally Posted by rtv900 View Post
migs put way less heat into a part than tigging does
Quote:
Originally Posted by isotopesope View Post
unless you run a pulser! i recently added a PC-300 to our Syncrowave 250 and am beyond impressed with the results. it reduces the heat affected zone tig-nificantly!
I weld all my stainless using an AlphaTig 200X set to 45A for your typical exhaust tubing. The key, based on my experience, is using an aluminum flange with a section of aluminum tube welded to it and aluminum flat welded to the end of the tube. I drill/tap the flat and put a 1/8NPT to hose barb fitting in there and it works great as a heat sink/backpurge port. Clamping the steel flange to the aluminum flange keeps it nice and true and helps dissipate some of the heat.
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Old 07-05-2018, 02:29 PM   #12
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^ interesting. How long are your beads?

I haven't had any luck welding SS flanges with my eastwood tig. I could make it work by doing about 1" long runs on opposite sides with time to cool down, but I feel like there should be a better way...
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Old 07-05-2018, 07:50 PM   #13
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I also warped v band flanges with my mig. If I tacked them with the mig and brought them over to fobia fab he would finish them with his Tig and they turned out perfect.
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Old 07-06-2018, 07:34 AM   #14
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Quote:
Originally Posted by Bad Noodle View Post
^ interesting. How long are your beads?

I haven't had any luck welding SS flanges with my eastwood tig. I could make it work by doing about 1" long runs on opposite sides with time to cool down, but I feel like there should be a better way...
Depending on the diameter of the tubing they are between 1-2" as I weld and rotate the tube to reach the next section.
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Old 07-06-2018, 02:05 PM   #15
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^ Cool, thanks for the info. So I guess the trick is having a block of AL as a heat sink, tight clamp, and shorter breads.
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Old 07-07-2018, 09:22 AM   #16
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dont let anyone tell you differently, mig and tig can accomplish the same thing as long as you have the proper welder. dont expect a flux core welder to weld as good as a tig but a good mig can weld as good as any tig.
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Old 07-07-2018, 12:19 PM   #17
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It should work, as others have said be careful of heat warpage. A technique I've seen used on similar projects is to lay one weld at a time on opposite sides and keep going one at a time to avoid overheating and keep the weld more airtight.
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Old 07-09-2018, 07:58 AM   #18
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^^ Agreed but in order to get clean beads on SS with a MIG you need a good machine and tri-mix (expensive) rather than the standard 75/25. I've welded SS flanges with a cheap mig successfully, but the splatter was a pain to clean up.

The nice part of using a tig (bought the eastwood one) is that there is 0 splatter and it's easy to go back and fix any pinhole leaks. The bad part is you go through a lot of welding gas with a 5s post flow requirement.
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Old 07-10-2018, 08:55 AM   #19
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since we keep bumping this, i'll put my two cents in.

Ive used a ton of differnet vbands. They come in many types and are far from universal. The clamps usually work on them all but the flanges themselves can be all machined differently. Ive used ebay, speedyracer, Ace Race Parts, summit brand etc..

The Ace race parts are nice but the male/female lip inside is machined very tight, any warpage makes it hard to get the flanges together at all, and the lock nuts they ship with make them impossible to remove, trust me, dont use their locking nuts. The Summits are also machined male/female but slightly looser. The clamps arent as nice as Ace's but the flanges are pretty equal.

I used to fluxcore everything, and it did just fine on everything but preturbo stuff. The only probably was from trying to stitch weld to spread heat, i often ended up with pin holes, and warped flanges, mostly at the turbo. I have since gotten a tig, and i no longer fluxcore exhaust parts. When i first started tigging, i did a lot of autogenous welding (no filler) This would add a ton of heat into flanges that were slightly bigger ID than the pipes OD. Works fine on thicker wall butt welds but not so much on flanges.


Like mentioned above, best thing to do is clamp a dummy flange to the one your welding, use as little heat as possible, and a 1/16-3/32 filler. A 1/16 tungsten may help as well to keep heat out of the flange. Let cool completely before unclamping. This is all based on stainless steel. Mild steel doesnt warp as easily and is much easier to work with, but seriously, who wants mild steel exhausts.


downpipe and axleback for exotruck. all done with a $400 harbor frieght tig, and about 8 hours of seat experience




Last edited by no694terry; 07-10-2018 at 09:03 AM.
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Old 07-14-2018, 10:30 PM   #20
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That turned out nice with only 8 hours of torch time! I was looking at the new harbor freight Vulcan tig machines they look really nice.

I would like to see more of the exotruck, I seen a few photos on the romraider website but that's it. Do you have a thread on here?
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Old 07-15-2018, 08:01 AM   #21
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Quote:
Originally Posted by TDagen View Post
That turned out nice with only 8 hours of torch time! I was looking at the new harbor freight Vulcan tig machines they look really nice.

I would like to see more of the exotruck, I seen a few photos on the romraider website but that's it. Do you have a thread on here?
Thanks. I used up about a bottle on muffler so I guess im over 20hrs now.

IG @exotruck

Or the long version
https://www.rs25.com/forums/f145/t236641-terrys-tube-ruu-500hp-exotruck.html
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