Shrinking metal? Heating it then putting cold rag on it?

[brrymnvette]

As my pops was helping me do some bodywork on the Corvair, he told me I need to shrink the metal. Now grant you this is the blind leading the blind and deaf here. He said to get a torch and heat the metal up then take a wet rag and put it on it. He said it'll shrink the metal and help pull some of the small hammer head dings out. Any truth to this or advice? I've NEVER done any body work until 2 days ago. I'll post pics of the damage once I find my camera.

[wiedemab]

The way we've done it (Dad and I - he's a bodyman of about 40yrs) is to find the stretched spot ie: ding or dent, heat a small spot cherry red with the torch, hammer and dolly it with a shrinking hammer (looks kind of like a meat tenderizer) and then hit it with a wet rag once you worked it into shape. The quick cooling in my understanding hardens the metal and makes it stay put.

When you put the torch to it, the metal will either swell inward or outward - it's kind of weird the first few times. It's much better to do this with two people. One with the torch and the wet rag and the other with the hammer an dolly.

Here is a pic of the lower quarter on my Mustang. It had been dented pretty good once upon a time and fixed with a bunch of mud. We were able to get it pretty darn close to where it only took a light skim coat of filler. To really get it perfectly smooth you almost need to planish it with a planishing hammer, which we don't have!

You can see the heat marks - notice the size. You don't want to heat a big area, so don't use the cutting tip on the torch, get a small welding tip or something close.

https://static1.pt-content.com/images/pt/2008/08/DSC00740-1.jpg

https://static1.pt-content.com/images/pt/2008/08/DSC00741-1.jpg

[brrymnvette]

Thanks! That helps alot.

[TonyL]

the fire and rag method is old school and can go both ways, it can cause the areas to raise outward also. Eastwood makes a disk, and utilizes a spray bottle, for better, more reliable results.

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[TonyL]

vs the old school fire and water method. Note the irregular surface created by his work. (it can be dollied out though... just saying.)

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[wiedemab]

Yeah - I gotta get one of those discs and learn how to use them. It does take some hammer and dolly work after the torch treatment.

[brrymnvette]

Well, we took it from this
https://static1.pt-content.com/images/noimg.gif

To this in about 3 hours. I'm just starting on it, but I think I've made tremendous headway.
https://static1.pt-content.com/images/pt/2008/08/DSCN1560-1.jpg
https://static1.pt-content.com/images/pt/2008/08/DSCN1563-1.jpg
https://static1.pt-content.com/images/pt/2008/08/DSCN1561-1.jpg


I've got a long way to go, but I'm stoked I've gotten it even this far. Now instead of having to replace the entire quarters like I thought I would have to, I'm only going to have to put a patch panel on the lower rear of the drivers side.

Tony, thanks for the links.

[TonyL]

No prob! I'm just glad you're working on that vair!

[BRIAN]

Shrinking discs work and are perfect for somone who is new to metal work. They work slow and will not get you in trouble as quick as a torch. Check Ebay they are on there.

I don't know anybody who thinks those serrated face hammers work at shrinking metal. I think years ago Ron Covell did a story about them in Street Rodder?

By the way the 1st step is to take the area down to bare metal before starting. You might want to also put a little pull on that rear panel and it will pop more into it's final shape.

Good luck.

[brrymnvette]

Thanks for the tip Brian. I'll give it a try.