Need Muffler Mod-Brazing Help

[RES]

I now have my rinky-dink Brazing Kit which comes with Mapp gas and about 2 minutes worth of Oxygen and a couple of differant kinds of brazing rods. Because of the limited amount of oxygen, there is no time to waste. Here what I plan to do.
o I am adding a 16mm tube to the side of a 038AV muffler at a 45 degree angle Lakeside style.
o I plan to make it fit as tightly as possible. No gaps
o I will then use my torch to heat the tube and muffler cherry red and start filling the gap with a brazing rod.

My questions are as follows:
o Which rod should I use, the bare one or the one coated with flux?
o Do I need a can of flux? If so, how do I use it?
o Any other helpful suggestions?

 

[Lakeside53]

You won't be "filling" with rod like you can with steel.. Get both pieces (in the area you want to braze) cherry, heat the rod slightly, dip in flux, apply to the steel with flame. It will "run" instantly around the SMALL gaps. Brass is not for bridging larger gaps. You can use flux coated rods but it good to have sme extra flux around.

Practice on some thin sheet first. Don't get the work too hot; don't forget to chip off the old flux when cold. I use 3/32 rod.

 

[Stihl 041S]

For brazing,.clean bare metal, flux, and a 2X flame. And what Lake said.

 

[timberwolf]

Brass would be my last choise for working on a muffler. With minimal equipment it is not an easy task, and with heat and stress it tends to crack. Also once it has been brased it basically cant be welded without grinding every trace on gold tinge out of it.

If you can weld it, IMHO that would be better. MIG easiest, TIG maybe best quality wise or gas weld with filler close to the base metal might be 409 or someting like that. Likely could even arc weld it with 1/16 inch rod down in the 20-40 amp range.

 

[motoroilmccall]

If he can't braze (or hasn't before) he probably can't weld real well either. The last thing I would do is give an inexperienced welder an arc rod and say weld it good. He'll burn through it in no time without even knowing it. Brazing will work, plenty of us do it that way. Welding would be nicer, but it sounds like he doesn't have a welder. My 110v MIG works perfect for that kind of stuff, the big Lincoln just has too much power.

Go with the brazing, just make sure things are tight!

 

[Lakeside53]

I've brazed maybe a 100 mufflers.. never had a failure... ever...

 

[Stihl 041S]

I've brazed maybe a 100 mufflers.. never had a failure... ever...

Properly done 125,000 psi tensile, strong enough for most mufflers.

 

[Bowtie]

I use flux coated brazing rod, and knock most of the flux off. There is enough left that I get better results that way. The way I have been doing mods with the flux on, the flux makes a damn mess, and the brazing quality is diminished. This works for me, and I have never had a failure.

 

[timberwolf]

Suppose the heat and vibes in a chainsaw muffler are not as bad as header pipes on a sled, know there brass did not stand up well.

Good point on arc welding, I was not trying to say that it is easy to weld thin stuff, but certainly could be and has been done before.

Mig with gas for stuff like that is slick, not the neatest, but quick and easy, no need to fit things up real tight either. Flux core wire not so much for trying to weld in tight corners and such.

 

[motoroilmccall]

:greenchainsaw: You'd be suprised some of the things I've welded with flux cored .030 or .035 wire, it sure ain't perrty, but it holds real well, and I can weld a lot of different thicknesses of metal with the stuff. Its all in the operator!

 

[timberwolf]

But when trying to fill in gaps in corners and such, it is easy to get slag inclusions with flux core. With some care in chipping and cleaning though sure you can do it.

I have not used much flux core since going to gas. Flux core is not much good on 22 to 24 gauge sheet. Been there done that. If the metal is thin enough that you need to back step or run short beads flux core is not the ticket.

opperator yes, that is one of the biggest factors, however I'd still pick the work from an average welder with right equipment and materials over a "pro" job done with the wrong stuff.

 

[timberwolf]

Welds that arn't pretty are good indications of welds that arn't as sound as we like to think. Thats just cover up talk for using the wrong equipment or lacking the skill to use it. If there are uggly stuff like big bubbled beads, undercutting and inclusions chances are the metal is not joined through the whole thicness and is not sound throughout.

Granted though, with gas mig it is easy to lay down an atractive weld that looks great esp with light wire and low power but be lacking joint strength and penetration.

 

[teacherman]

What about using a Century wire feed welder? I have an old one that is gathering dust. It can be adapted to use a shielding gas, but that requires a kit. Brazing is so much easier for me........

 

[timberwolf]

Hey if you got the brass set up give it a whirl, if it don't work, heat it up pull it apart and grind the brass off and get the mig fired up.

 

[gink595]

Welds that arn't pretty are good indications of welds that arn't as sound as we like to think. Thats just cover up talk for using the wrong equipment or lacking the skill to use it. If there are uggly stuff like big bubbled beads, undercutting and inclusions chances are the metal is not joined through the whole thicness and is not sound throughout.

Bingo!!

I'd just braze it, you can use steel filler rod and a can of powdered dipping flux. If you don't want to use a brass filler. Not a real big deal, put the heat to the thicker of the two joining metals and start applying the filler rod, the heat will pull the filler around.

 

[gink595]

Hey if you got the brass set up give it a whirl, if it don't work, heat it up pull it apart and grind the brass off and get the mig fired up.

If you do this make sure you get all the brass off, you can't mig over brass.