zggill04

Alright, this is just a what would you do question. I have a few different options but it's been a few years so I'm looking to make this as painless as possible.

On the roof of the 68 Bird, there are two small holes, you could fit about a finger in each one and about fill it up but it goes all the way through. Some idiot tried to put clear caulking in it. It looks like it was from a vinyl top that trapped water for many years. How would you guys fill this?

1) Weld it closed. Then bondo it. Though I'm worried about the heat making a bondo nightmare for me right now. Like I said, it's been a few years and it's in a noticeable spot.
2) Fiberglass it. Put some matting underneath then put resin over it and it would be pretty painless.
3) Lead fill, which has been awhile and will be harder to get.
4) ????

This needs to last and look good as it's going to be a quality paint job.

Let me know your thoughts.

rmodel65

weld it closed and fill with filler, just dont get it to hot to warp everything.

and if you want to use lead anywhere reconsider and use metal to metal filler

green_blurr

The roof is going to be very thin use a mig welder and get a wet rag. Tack then cool it down with the wet rag then repeat the proces untill the hole is filled. Take a grinder with a flap disk to smooth it out. Then you can correct imperfections with body filler. Also as a precautionary measure you can glue a piece of rubber to the underside of the weld to keep anything from leaking through or up.

rmodel65

also idk if you interested or not but you can panel bond a small patch if you can get to the back side. its extremely corrosion resistant and as strong as a weld. and there's no chance of panel warping. honegoldcoupe uses it all the time.

zggill04

rmodel, what do you mean by panel bond a small patch?

MBDiagMan

Although I personally MIG in a patch for such situations, rmodels suggestion is a valid one. The panel adhesive products are getting better and better all the time. If you decide to use the adhesive, however, do some research, pay close attention to the instructions and as with any bonding agent (paint OR adhesive) preparation is EVERYTHING.

Also, I personally NEVER use the wet rag method that green blur described. Obviously it works well for him, but putting the metal through such drastic heat cycles is risky.

I'm an old dog so my old habits die hard. I would cut the hole out to make sure that all the corrosion is gone. When you see a rust through area, it is an iceberg and you're only seeing the tip. Cut out all the corrosion, but keep the patch as small as possible. Once the hole is made, cut the patch to fit as well as possible with about a 32nd of weld space between the patch and the roof all around.

Do whatever it takes to get the patch in place and FLUSH with the surface. You won't be able to use ice tong vise grips so you will have to get creative, but get the patch in place for the first couple of tacks.

Once the patch is in place, put a small tack with a MIG welder USING SHIELDING GAS. This is NOT a job for flux core. After the first tack, make sure the opposing side of the patch (not the back side, but across the surface of the patch) is still flush and then make another MIG tack. Now go halfway between these tacks and make a couple of more tacks. Keep leap frogging around the patch with your tacks until it is all stitched up. Since it sounds like this will be a small patch, allow lots of time between tacks to prevent overheat warpage.

Once the patch is all stitched up, grind it smooth. Take your time with the grinding step also, since you don't want any overheat warpage.

You can also do this with TIG equipment if you have it handy, but MAKE SURE YOU DON'T ALLOW HEAT TO BUILD. Overheating can warp that roof until you will never get it straight again.

SJs 66coupe

I would be curious to know more about that as well. I have a small spot or two that seems like replacing entire panels may be a bit of over kill.

MBDiagMan

The panel bond compound is NOT used to fill the hole. It is used as an adhesive to glue a patch piece into the hole. It is becoming more and more acceptable all the time. In fact is probably to the point these days of being routine.

This adhesive is expensive and is available in several different versions with the difference being their set up time.

fakesnakes

Doc's approach is the best in my opinion. The only build I would offer is to use two magnets to hold the patch in place and start your tack welds on the opposite sides from where the magnets are located. Once you have a couple in place, remove the magnets and add a couple where they were. Use a hammer and dolly periodically to ensure the patch is perfectly positioned as you add tack welds to eventually end with a thoroughly welded patch. Bonding panels in place is very good, but they can not be butt joined. On the roof, you want a smooth butt joint.

zggill04

Yeah, Doc's approach is always the one I had used. Just the size of these holes is small... even after clearing away the rust. Is almost seems like it would make more sense to glass it, but like I said, it's going to be a quality job, not just something thrown together. I have to sand the whole roof down though, because it's cracking all the way down the roof. I might have to weld down the whole roof which would suck. I guess time will tell. The only two visible holes are on the same spot on the roof, just opposite sides.