lead or bondo?

[nr1freak]

hi! as i'm nearing completion on my sheetmetal work i'm beginning to wonder what would be best to use to fill up the large seems that i have after replacing the quarterpanels and other parts of the car, lead or bondo? i know using lead is nothing short of an artform and it takes a lot of time and eventhough i've done it before i'm not sure i'm doing it completely right... but did they use lead back in the days because there wasn't a descent bondo available at the time or is it just so much better? i live in belgium so it can get pretty wet over here, eventhough i will avoid taking the car out when it rains, you never know...

[dutch]

hello neighbour 
what seams do you mean?  the only leaded seams from factory were qtr to roof and qtr to rockerpanel/

[nr1freak]

hello neighbour 
what seams do you mean?  the only leaded seams from factory were qtr to roof and qtr to rockerpanel/

yea, and the fact that they did use lead makes me wonder why... the seems i'm talking about are the ones on top of the new quarterpanel where i spotwelded them to the original chassis (in the picture the new panel is not welded yet) i'm using a special plier to bend in the original panel a little bit so he new panel falls in place and doesn't stick out or lay on top of the original panel, so the seem isn't really that big or deep but because it's all across the lenght of the rear panel i don't wanna take risks of bondo cracking or peeling off after a few years, i want it to last!!

[dutch]

... I would cut both parts of the qrt to fit flush and fully weld  ,instead of overlap and spotwelds. If you use bondo, rust will eventually surface, coming from between the layers. That is a huge seam to lead... with all heat you have to apply, big chance the qtr will look like the Ardennes.
If you decide to weld the seam completely,  it`s a wise thing to grind down the welds on the inside as well.  If you don`t, you will see the weld on a hot day. Lead or bondo.

[nr1freak]

... I would cut both parts of the qrt to fit flush and fully weld  ,instead of overlap and spotwelds. If you use bondo, rust will eventually surface, coming from between the layers. That is a huge seam to lead... with all heat you have to apply, big chance the qtr will look like the Ardennes.
If you decide to weld the seam completely,  it`s a wise thing to grind down the welds on the inside as well.  If you don`t, you will see the weld on a hot day. Lead or bondo.

i think a 1.5m weld will put in a lot more heat than that small gasburner i use just to melt the lead, that's the trick i guess, to melt the lead without actually heating up the metal too much! and if the lead runs inbetween the 2 plates (which i think it should, when done correctly) i don't think there will be much room for rust... the backside of the seam, i will try to fill up with sealer or something... hmf, need to get educated about this one!

[7071 challenger]

Hi guys...

I'm no expert when it comes to body work, but  a friend of mine, which is, (an expert), told me to go with bondo, for two reasons: 1) You have to apply a lot of heat to properly install the lead, (Maybe Chrysler had techniques we don' t know about back then). And also, (and I think this is really important), he said the best way to prevent rust before you put bondo, is to apply "epoxy primer'' inside the joint to seal any naked metal. Now,  anybody can figure that the epoxy primer is useless if you go the lead route. He was saying that, over a certain time, ( a couple of years), it will rust, because there is always very small pin holes in the lead (not visible with naked eyes), and rust will start its work. I don' t know for you, but he convince me: I' m going the bondo route.

Robert

[72rtchallenger]

bondo by itself will telegraph out of the seam line because of the welds underneath release some type of gas (ask me how I know  )  which is why the factory used lead ,to my knowledge that is why, anyways I would get the epoxy putty  mix from por-15 which is what I am going to try as soon as I get back on digging out all the bondo one of these days

[dutch]

i think a 1.5m weld will put in a lot more heat than that small gasburner i use just to melt the lead, that's the trick i guess, to melt the lead without actually heating up the metal too much! and if the lead runs inbetween the 2 plates (which i think it should, when done correctly) i don't think there will be much room for rust... the backside of the seam, i will try to fill up with sealer or something... hmf, need to get educated about this one!

I don`t agree.    you will have a lot of heat when using lead.  You can take all day to weld that seam, and regulate heat.  Laying the 2 pieces of sheetmetal on top of each other is not what I would do.  I agree with 7071. Fully weld, epoxy and filler

[nr1freak]

difficult this one... i've been a welder for ten years now and i know, if i MIGweld the panels, even if i take my time and cool off every 2cm or so, 1,2mm steel will seriously warp, because any weld will always shrink and pull everything that it's attached to with him, so yes, it would be better for the rust to weld completely leaving no gaps or voids anywhere, but i'm sure i will ruin my pricy aftermarket quarterpanels 
when you use lead, the first thing you do is brush on a sort of flux-paste, you quickly run over it with a flame (barely heating up the metal) rinse that off with water so you get a clear and shiny lead-layer that sticks nicey to the metal, and after that you melt the lead into it (mainly focussing the flame on the lead, not the metal... then, when it's still dough-like, you use a wooden thingy to smear it open like you would regular bondo... i think lead melts at temperatures way lower than the temperatures needed to warp metal but i'll have to dig out my schoolbooks for that   
true, there will be small pores in the lead but lead itself won't rust so... the backside of the seam will still be accesible through the trunkspace so i could maybe brush my little sandblaster along and inside of it, put a layer of epoxy and put a ****load of filler in there!

[GCC]

Here is the driver's side lower quarter/rocker seam on my convertible (upside down on rotisserie).  The quarters were replaced many moons ago and are rust-free.  (I am in the process of completing the rest of the body work).  The seams were filled with bondo at about 3/8-1/2" because they are recessed that far from the rocker surface.  The metal was epoxy-primed before the bondo.  I ground out all the bondo to take a look at the seams.  There was no rust anywhere while removing the bondo and primer.  Both sides of the car have 4 spots welds and the vertical seam is welded complete.  Even with all of this, the bondo was separating along the lower horizontal part of the rocker/quarter.  (the bondo was not cracked anywhere on the seams).  I believe, though, that this was due to adhesion problems, but could have been due to flexing of the convertible body.  I have heard and read that the best method is to epoxy-prime bare metal before and after filler work.  But I think you also need to really scuff up the primer before adding filler.  Being a convertible, would it be wise to cut out the seam, and replace with a metal patch that is flush with the rocker and quarter?  I have never leaded anything, and am hesitant to do lead on these seams, but also don't want the bondo cracking or separating.

[Topcat]

When heating the panel, go in figure 8 patterns. Then work out. As long as you don't get too close, it won't warp. I leaded mine wherever there was supposed to be lead. I ended up with less than a nickel thickness in filler afterwards.

Hot days telegraph the filler to stand out like a band-aid.
Don't use filler to fill in the seam!

[Topcat]

Once you've mastered the heat, you can even lead against gravity.

[GCC]

Looks nice.  About how thick is that lead?  What kind of torch is needed?  Oxy/acetelene; propane?  Or do you need a jewelers torch?

[72cudamaan]

When heating the panel, go in figure 8 patterns. Then work out. As long as you don't get too close, it won't warp. I leaded mine wherever there was supposed to be lead. I ended up with less than a nickel thickness in filler afterwards.

Hot days telegraph the filler to stand out like a band-aid.
Don't use filler to fill in the seam!

Skim coat of body filler after leadwork is done. Leading should be done in one sitting to avoid
porous areas and create air pockets. Lead work is fairly easy if you take your time.

[nr1freak]

I use a small buthane or propane burner, with those small handheld gascontainers you use on your campingtrips to light the bbq!, you know, with about a 1" flame-exhaust! an oxy/acetylene flame is much too small and concentrated and the heat is too intense, you don't want to heat up small area's of metal as this increases the warping! Figure of 8 movement seems like a pretty good idea! As well as not putting bondo in the seams, i think bondo becomes hard like an eggshell and therefore brittle while lead tends to give way with the movement and vibration of the metal... Hm allright, i think we're getting somewhere here   not so sure about defying gravity though... Better get me that rotisserie!