New guy with stupid question about brazing.

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Hey guys, I have been lurking around and find some great stuff. But I haven't found an answer to this particular question.I am an autobody tech and will find brass here and there on cars. Over the years it has been in the same places. Usually on the ends of quarters, front up by the rear window or down at the back in the gutter. But always at the ends, sometimes at the corners of roofs. Anyway, European, Domestic, Japanese, you will see this here and there, and then most cars will have none at all. What is the use of this brass for? Brian
Reply:the brass is used to fill in the seams instead of welding the seams together..its easier to file/sand than welding is...and better than using "bondo" on a new veihicle  ...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Welcome, Brian. I'm sure you'll enjoy this forum. I guess I'm as "stupid" as you because I can't answer that. I've always believed there is no such thing as a stupid question. Without questions we'd all be floating in a sea of ignorance. I'm sure someone here will be able to provide an answer for us.           Again, welcome,                                MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Thanks,Zap. I kinda thought that was the purpose, but wasn't sure enough to say so. In this age of "lead free" that makes sense.                           MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:You know what ? the really "stupid guy" is the one who thinks he knows it all , because NOBODY knows it all . I've had people say to me "boy, you know all about welding ". that frightens me  and I say" knowbody knows ALL about welding ". we don't live long enough to learn it all and i'm glad we have a forum like this to exchange knowledge and ideas .  I guess this is to say that maybe the only stupid question is   one that ISN'T  asked. if one person is wanting to know something , i bet there are more out there with same question .Last edited by Roy Hodges; 05-14-2006 at 09:38 AM.
Reply:Thanks guys. The thing is, they aren't "filling a seam" with it. I'll try to get some pictures. What they will do is right at the top of a quarter in the window channel at the bottom of the rear window, they will "flow" a little brass. This will be where the quarter overlays the upper panel (below the rear window). They will braze right there in the bottom of the channel where the window is urethaned in, but only about a half inch or so of the seam. They will do the same thing in the trunk rubber channel at the very back. Just where the gutter from the quarter meets the lower rear body panel in the gutter, a little 1/2" (dime sized) brass will be there. On Mercedes and other Europeans there will be that, along with a little different use. On the rear of the quarters there is often a "filler" panel under the taillamp. This filler will go from the decklid opening to just around the corner on the quarter under the tail lamp. A number of Hondas will have it for instance, but theirs bolts on. On the Mercedes it is spot welded all the way around, even on the inside where it is a "pinch weld" on a lip folded in on the quarter and the filler and they meet head on behind the skin of the quarter. THAT seam, they will braze up, from top to bottom like a seam sealer. The other locations look more like a "added safety net" of support. I think I may be answering my own question.   The brass flows out OVER the metal at this point. It may not be "stronger" to braze (or is it?) but at this point it holds JUST the very end of this metal in place. The zillion spot welds holding it on may do just that, but the end, the very end lip of metal can't be held with anything but a spot weld a half inch or so away. They want that VERY end to be held.Hmmmmmmmm, makes sense. But then the question still has to be asked, Why do some cars have it and others don't? Other than "there is no real answer" other than the engineers thought it was needed so they did it. There was no difference in "Stress" there from car to car, the engineers who laid out the welding needs for the car are "fans" of brass.  What do you guys think?Brian
Reply:Originally Posted by MARTINSRThanks guys. The thing is, they aren't "filling a seam" with it. I'll try to get some pictures. What they will do is right at the top of a quarter in the window channel at the bottom of the rear window, they will "flow" a little brass. This will be where the quarter overlays the upper panel (below the rear window). They will braze right there in the bottom of the channel where the window is urethaned in, but only about a half inch or so of the seam. They will do the same thing in the trunk rubber channel at the very back. Just where the gutter from the quarter meets the lower rear body panel in the gutter, a little 1/2" (dime sized) brass will be there. On Mercedes and other Europeans there will be that, along with a little different use. On the rear of the quarters there is often a "filler" panel under the taillamp. This filler will go from the decklid opening to just around the corner on the quarter under the tail lamp. A number of Hondas will have it for instance, but theirs bolts on. On the Mercedes it is spot welded all the way around, even on the inside where it is a "pinch weld" on a lip folded in on the quarter and the filler and they meet head on behind the skin of the quarter. THAT seam, they will braze up, from top to bottom like a seam sealer. The other locations look more like a "added safety net" of support. I think I may be answering my own question.   The brass flows out OVER the metal at this point. It may not be "stronger" to braze (or is it?) but at this point it holds JUST the very end of this metal in place. The zillion spot welds holding it on may do just that, but the end, the very end lip of metal can't be held with anything but a spot weld a half inch or so away. They want that VERY end to be held.Hmmmmmmmm, makes sense. But then the question still has to be asked, Why do some cars have it and others don't? Other than "there is no real answer" other than the engineers thought it was needed so they did it. There was no difference in "Stress" there from car to car, the engineers who laid out the welding needs for the car are "fans" of brass.  What do you guys think?Brian
Reply:is there any way to look underneeth the area with the brass on it?could answer some questions right there..dented?dimpled?who knows?  ...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Nothing at all Zap, we are talking new panels assembled at the factory. Picture to pieces of 22 guage steel 1"x12" laid on top of one another perfectly but with one two inchs back from the end of the other. These two pieces are STRSW an inch apart. At the end where the upper piece is over two inchs, it is brazed. It is that simple. The entire quarter is spot welded on with a STRSW and at the corner here and there it is brazed. No damage, no "sealing", nothing like that. Brian
Reply:maybe its at stress points where the brass will give but the metal would crack??now we have to find out  ...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Originally Posted by zapstermaybe its at stress points where the brass will give but the metal would crack??now we have to find out  ...zap!
Reply:The 70's Chevy trucks have a braze in the A-pillar.  I believe this to be a joint between two separate pieces of the body.  The braze gives more strength than the spot weld and can be done with less distortion than an arc weld.  The manufacturer could weld it a little bit at a time (stitch) like we do when we repair sheet metal damage, but that would take way too long.  I don't necessarily agree with it being easer to shape and file, non-ferrous metals tend to load up grinding discs fairly quickly.  A brass brazed joint has a tensile strength of ~45ksi.  Cheapo steel can have a tensile strength as low as 30ksi.  The brazed joint is acceptably strong.
Reply:I am an autobody tech and will find brass here and there on cars. Over the years it has been in the same places. Usually on the ends of quarters, front up by the rear window or down at the back in the gutter. But always at the ends, sometimes at the corners of roofs.
Reply:we may have the answer  or not..... i asked my boss and heres what he said..."the brass is "placed" where in the past rust and corrosion would start..by window drain areas ..corners..etc..mercedes benz was the first to do this and others soon followed"weather its true or not i dunno  but i count it as a viaible answer... ...zap[!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.