Do you guys know of any trick to straighten a bent roof to perfection() even if it involve using some filler? I heavent had any luck in the past, they all seem kind of bent after i finish painting the car Its mainly caused by the metal being stretched, i have used metal shrinking hammers and also a torch shrinking method but none have worked.

Would you guys recomend cutting a line and then welding it back after the roof has been straightened?

Any help is appreciated.

torch and wet rag:
http://www.youtube.com/watch?v=mptiiRLEJs0

with hair dryer and copmuter dust off (co2 bottel):
http://www.youtube.com/watch?v=q0UAUBE-Hmg
http://www.youtube.com/watch?v=ILVWPzO_swY

you can maybe mix the technics together and use the dust off (co2) with the torch since the co2 comes out alot colder then just water.. hop it helps

Welding a large piece will warp the thin metal, so you'll be right back where you started from.

Try using a dolly and shaping hammer.


Or try a shrinker-stretcher. But be careful, this heats up the metal real fast and can warp it too. I've never used this, just seen someone else do it.


In the end you'll still probably have to use filler, but a very small amount.

_________________

Its very hard to guide you with advice without seeing some good photos of the roof and even then it wont be the best. Without meaning to offend any of the posters here, I would disregard most of the advice given.

If your asking these questions then you would have very little experience.

1. I wouldnt bother with using a torch, that will be the quickest way to trash your car.
2. You also wouldnt bother using a wet rag, Co2 or other accelerated cooling method with a torch on the roof to assist in the shrinking process. Naturally letting the metal cool and shrink will be a much better approach. The metal needs to be moved gradually, you would only use a wet rag if you are trying to move/ correct a large surface area roughly !
3. After heating a section of the roof to a cherry red, you need to use a hammer and dolly over the area to control the shrinking and not to over shrink the area.
4. As Ben has mentioned a hammer/ dolly and shrinking disk is a far better approach for an amateur.

The roof panel would have to be the hardest panel on a car to get right due to supports under the roof panel as well as the roof having a very low crown or shape. In other words almost flat.

Im currently finishing off my roof which had punch marks all over it. I thought I had it almost perfect after many lots of hours of work (weeks) and after spraying a guide coat it is far from perfect. Ive spent last weekend shrinking some high spots and reworking a couple of other areas. I'll next spray the roof in polyester which is very thick and use that as my guide coat for sanding with a very large block. The polyester will fill any minor imperfections which would be difficult to remove without causing other problems with the roof... ie chasing your tail with repairs.

I'll collate my roof repairs over the next couple of weeks and update my post. There is no real easy way to fix a roof unless you load it up with polyester and block it., however using too much polyester will probably result in paint problems and is a bad repair.

find another roof to practice on first

Banzai toyota- Too late, but its definately a great idea.
rkkopra73-There is no prefesional sheet metal man here , they all are about my level of crafstmanship; i wouldnt pay someone to do the same crap im doing .

Gypsy, thanks for the advice; It tells me that not all bodyworking books are good, even more if they are 20+ years old Would really apreciate pictures of your prject so i can use as reference in a future roof staigthening.I already painted the car, it will stay as is for a long time, I need a DD. 79 Civic doesnt have much damage in the roof; pictures are really far from coming because i need to fix other cars car first.Im already familiar with welding and patching up cars and hammer and dolly work, also painting; But i have never been able to shrink metal to perfection without some( really some) body filler( yes im ashamed ).I consider myself a good amateur Which of the before mentioned methods did you use to shrink the metal?

I love car Bodywork


edit.I would like to try that rare grinder in a future, about how much does it lower the high spot?

http://allmetalshaping.com/

go there and introduce yourself. a Wealth of knowledge there. I went to a weekend meet at a members shop and knocked out 3 repair panels for my car