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We've been doing the body prep work getting ready to paint my '65 Fastback. We have some stress cracks at the quarter/roof line and it seems from reading old posts that the quarter/roof line joints were welded with "lead".

Well my body shop would rather not remove the lead and wanted me to ask the forum about some good materials to put over the top of the lead and steel to strengthen the seams before using bondo. He does not do lead welding.

How do we properly address these stress crack areas before painting. Would any of the metal adhesive materials work on lead and steel and not be prone to future cracking or do we bite the bullet and clean out all the old lead? Which ones would be best.

Brian
 

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Actually the seams were induction spot welded at the factory. Those seams are recessed and lead was the 'stuff' of the day to fill that area. Any of todays fillers will bond to lead. The problem is it will probably crack again because of body flex.
 

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You might want to explore why the stress cracks are happening in the first place--rust in sub-frame or PO testosterone? ;)

Stress cracks can be annoying. Depending where and how visible, the easiest way to stop the crack without welding or brazing is to drill a VERY small (depending on the size of the crack, but probably less than 1/8") hole right at the end of the crack. Add POR15 or other similar rust protectand to the crack and then add a thin layer of seam sealer/Dripcheck or several very thin layers of filler. OR, as leading isn't difficult to do (there are lots of books/tech articles on this mostly lost art), fill with a small amount of lead. Just be careful, wear a respirator, and don't expose yourself too much to lead. BTW, the factory used lead until somewhere around 68, but also (in later years) used filler itself.
Good luck on your project.
Daniel
 

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I'm assuming your cracks are in the same location as "everyone else's". On my 67 coupe they were about 1/2" forward of the "B pillar" on the surface where a rear seat passenger might rest his hand if the quarter window were rolled down. I didn't see any lead in this location on my car.
This has been discussed before and my conclusion is that the cracking is due to the flexing of the unibody. IMHO the only true remedy is the reinforce the body with subframe connectors in conjunction with MIG welding the cracks. Otherwise the cracks will return no matter how you "fix" them. I would welcome the thoughts of our opentrack guys as the stress on their cars much more than our street cars ever see.
I wouldn't bother about the lead unless it's in the way of your crack repair. Consider it the 1950's version of Bondo. Bondo wasn't too good in the 60's. It has since improved to the point that "leading" is pretty much a dead art.
 

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As a side note to this item...I replaced the full qtr on the pass. side and guess which side is the only one with the stupid stress cracks...arrrghhh! I welded the you know what out that puppy too! Used the fabulous cat hair bondo and a thin layer of regular for smoothness...oh well, live and learn. I did find a new friend at the cruisin' last sat. that offered to give me a hand with some real body working experience, this guy is retired from fixing all the troopers cars for the state so I am looking forward to some real good learning time. Maybe I can get it "right" this time around! :eek:
 
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