My project Camaro has an after market sunroof. I want to put a roof skin on to replace the sun roof. Any reason why this wouldn't be a good idea??

 

Same problem my Camaro had! I stuck an aftermarket sunroof in mine back in 1976 when it was a really cool thing to do! I had to weld in a donor section to fix mine. If I did it again I'd remove a complete roof and replace the whole roof.
Be sure you remember to replace the inner roof first! You need that to hold the headliner in! The inner roof can easily be patched in and wont matter. I cut my inner roof patch about 2" larger so I had an inch of overlap all around. Carefully measured the donor and my roof, so I'd be using the exact same location. Then I tacked it in with my wire feed at 4 locations, then just welded it in all around.
I welded my sunroof patch in the old sunroof hole. I made strips from scrap roof to weld all around the opening, then cut the roof section to fit my opening with about 1/8" gap all around. That gave me room for my tack welds to fill the gap and the plates gave me something to lay the roof on, and weld to.
It worked out great for me, but it was a lot of work to get that filled hole to be perfect. I spent days on it, and finally gave up. In the end the body shop guy spent about 3-4 hours geting it perfect, but he was cussing it too!

 

What BB427 says is true. Even seasoned bodymen will be cussing at welding in a roof patch. The metal is un-forgiving as far as warpage and is hard to get close to straight. You might also consider replacing the entire roof from a donor car. Place your welds at the windshield pillar and the factory quarter seam. You could also gain T-tops this way.

I see you are from MN. We are north of the metro and there are many cars in this area for roof donors.

 

Thanks for the feedback... When I look at roof skins, some specify that they are outer and some just say roof skin (goodmark)... To replace the inner roof, as you suggest, I assume that will have to come from a doner car or can these be found after market?

 

I don't know of any inner skins that are being reproduced, so donors are needed for that. I would not reccommend replacing the whole inner skin at the same time! The inner skin should be kept in tact to hold everything in place while you do the outter skin. I would fit in the donor inner roof before I even removed the outter roof. Just work through the opening. Once it's done then the roof will be ridgid enough to hold everything while the outter is replaced.
On my roof the inner was tack welded about evry inch, as I felt that was solid enough. The outter patch was welded solid, but with one tack at a time, and also by welding tacks from opposing sides of the patch, so I could avoid heat build up. I still got a minor amount of warpage, and had to use a spot welder to shrink the metal and pull it all into place when I was done. Just a real nightmare the way I did it.

 

So what I am thinking is I find a donor roof. Cut the inner roof skin about 2 inches larger than the hole and patch that in. Once that is done, replace the entire outer roof skin. Seems to me that would be easier than replacing the entire roof or the entire inner roof skin?

 

Yes, just cut through both roofs, or chop the whole top off.
I just took my cordless Sawzall with me and cut the posts close to the dash, then I cut the back about halfway up the rear window and horizontally towards the side glass. That will give you way more than you need of both.
When splicing the inner roof just do as mentioned and cut it a couple inches larger after you separate the inner from the outter. Be sure you measure where your old opening is, so you can get the donor hole in exactly the same location, or your bow slots wont line up.
Also, the two roof are glued together with construction adhesive, so you'll need to get a small propane torch and heat the inner roof in each spot to make the glue let go. If you don't have a torch you can use a hacksaw blade and reach inbetween the two to cut each spot as you gently pry it apart.
Once you've got the inner fixed, and before setting the outter for the last time (after trial fitting) you need to get some construction adhesive and squirt in in everywhere there is solid metal that's close together. Less than about 1/4" clearance between the inner and outter roofs. This will tie the two together to make it solid, and also eliminate any chances of rattles or squeaks from the two contacting each other.
Get the two glued together, then get the outter roof correctly lined up with all the edges. Be sure it's perfect before the adhesive dries. Trial fitting and reference marks will make this easier before the final placement. Once it's "squished" into place and everything is lined up, you can tack it once in about 4 places to hold it overnight. The next day you can carefully begin the tedious process of doing about 500-700 tack welds. Move around so you don't build up heat, until all the welds connect to each other. A tack about every 12" to start, then return to the first tack, and tack beside each previous tack, until it's all welded. You can also keep a bucket of cold water handy and an old rag to cool things once in awhile.
If you practice on some scrap roof first, it will make the process go better. I welded a bit before I did mine, but never any really light stuff like this. It was actually a little scarey at times, but worked out just fine in the end; even with my poor choice of filling in the roof, instead of replacing it all!
Boy am I ever glad the sunroof is a thing of the past on mine! It was one of those distractions that everyone looked at and said, "Too bad someone cut a hole in your roof."

 

Just got through watching a past segment of Muscle Car TV, and they were doing a roof replacement on a '68 Mustang using automotive adhesive! They did tack weld the corners, but all the edges just got adhesive caulk. Might want to look into this before you start your roof replcement. Sure made it look simple and easy!
http://www.powerblocktv.com/site3/in.../ep?ep_show=MC

 

Update... I saw that same episode and purchased it on DVD along with the entire roof they replaced on the Buick. I also now have 2 donor roofs to work with! My plan of attack is to patch the inner roof hole first, then put a replacement after market skin on the outer roof. The inner roof won't be too difficult and I can experiment on a donor roof with taking the outer skin off before working on the car. Then I even have a second donor roof as a backup if needed. I am still a couple of months away before I start doing the actual work, still getting everything lined up and ready to go! Thanks for all of the tips!

 

I'd enjoy hearing how it works out for you! Pictures too if you have a chance!