Oddmanout84 Posted January 26, 2011 Share Posted January 26, 2011 (edited) Ok, so my 280z came with one of those awful moonroof abortions when I bought it, and I've wanted to get rid of it ever since I first rode in the car. It leaks something terrible, can't find new gaskets for it, and it makes HORRIBLE whistling sounds on the highway at speed. Its time to go. Almost a year back, one of my buddies got a '73 donor car parked in his driveway and we swarmed it like a colony of fire ants. With essentially a "you remove it, you keep it" policy going, I claimed the roof and we sawed it off. It was a pretty good donor besides a small rust spot, but I didn't have a car to take it home at the time. It sat in the yard a couple months until I could borrow a scooby to haul it home. During that time not much changed, but I found the small rust spot on the front edge was a little worse than I thought. Now that I have my own handy dandy little MIG welder (Hobart 140), I can finally get around to this. I've welded my entire exhaust together so I'm not a complete newbie when it comes to MIG, but I will have to practice a bit on some scrap as its been about a year. I still feel pretty dumb for painting the car two years ago only now to ruin it, but the paint was cheap and I thought it would be harder to find a donor. This one sort of fell in my lap. Now I suppose I should have mentioned at the beginning, YES, I have searched and read other threads on how to do this swap. So far I've seen two methods: Option 1: Measuring and patching the big stupid hole itself. Option 2: Skin the recipient and donor roof a couple inches down the columns by drilling out the spot welds. Reweld donor roof in place of original. With my case, I've seen another couple possible options, and I'm wondering if they're feasible. Additional Option 1: I drill out the spot welds on the donor and cut out the rotted bits. After patching the new skin in I then weld in sheet patches for the rust spots and smooth them out. Additional Option 2: This is the one I'm a little more comfortable with. I cut the donor roof and my current roof at the line in the picture (which is still forward of the current sunroof hole) and patch the skin onto the spot welds in the rear, then weld the front. Like this. Hopefully this is clear enough. What I'm concerned about the most is what is going to be the easiest to align, will be blended back into the body with less effort, and would be better for avoiding warping. Though I feel the most comfortable cutting the roofs and welding them in as per the diagram, it would really suck if it didn't line up at all... Any thoughts? Edited January 26, 2011 by Oddmanout84 Quote Link to comment Share on other sites More sharing options...
cockerstar Posted January 26, 2011 Share Posted January 26, 2011 (edited) My approach is in here You're going to want a piece of copper to use as a heat sink and as a backer for filling in where you blow through! The metal on the roof is quite thin. I used a lincoln 120v unit, although I don't remember the amperage. Edited January 26, 2011 by cockerstar Quote Link to comment Share on other sites More sharing options...
Oddmanout84 Posted January 26, 2011 Author Share Posted January 26, 2011 My approach is in here You're going to want a piece of copper to use as a heat sink and as a backer for filling in where you blow through! The metal on the roof is quite thin. I used a lincoln 120v unit, although I don't remember the amperage. Thanks! Yep, that's one of the options I was referring to. Yours and another guy with an orange Z are the methods I've seen documented. He skinned the whole roof and rewelded at the original spot welds at the columns. Your way was the first that I had planned on doing. But to be honest, I was worried about using your method for a couple reasons. One was blow through and warping as you mentioned, the other was accurately measuring the "plug" that you put in the existing sunroof hole. How easy was it to measure and can you notice a difference in the roof once its finished/painted? Quote Link to comment Share on other sites More sharing options...
cockerstar Posted January 26, 2011 Share Posted January 26, 2011 From the first pic you can see how much of the skin I took from the original car. I laid this over the hole in my rood and traced it out. From there I flipped the skin over and followed my line about 1" out with a plasma cutter. Then it was lots of grinding (I probably could have gone closer than the 1", but I wanted to reduce warping as much as I could, and liked the extra wiggle room) to get the plug to fit perfectly into the hole. By going with the bigger cut I was able to make sure the skin was properly aligned because the curved edges hugged onto the roof and pulled it right into place. Take it slow, and your warping will be minimal. In the second pic you can see what it looks like tacked into place. Then I got greedy with the stitch welding and you can see all of the warping in the third pic. If I was going to do it again I would just keep filling in with tack welds, making sure that you're getting great penetration. Skip around a lot and take your time to keep the metal cool. It'll take longer, but you'll save a lot time in the long run with your body work! Quote Link to comment Share on other sites More sharing options...
spudly13 Posted January 26, 2011 Share Posted January 26, 2011 I just recently filled mine. I found a donar roof just like yours, Cut out the majority of the roof pannel. Held it in from the bottom lining it up perfect and tracing out the whole. Cut the piece a little big so i could trim to fit. Once i fit it and was happy i tacked it in and kept going around with tacks and grinding until it was completely filled. Afterward i had to go around with a hammer and dolly to smooth some areas out. But overall i was happy with how well it worked. Note. Be extremely careful not to put to much heat in one spot. It warps and bubbles really really easy. Quote Link to comment Share on other sites More sharing options...
Oddmanout84 Posted January 30, 2011 Author Share Posted January 30, 2011 I guess one of my last questions would be do you experience any "popping" sounds while driving around from the roof flexing, or is it pretty solid? Quote Link to comment Share on other sites More sharing options...
madlarkin Posted February 10, 2011 Share Posted February 10, 2011 The orange rustbucket keeps on giving. I still throw my vote in for patching the big horrible hole using the donor as a panel. Just seems to have the fewest possible scary issues involved. I remember the rust on the leading edge, are there any other issues? Looks like you trimmed it down, I thought I cut it longer. Quote Link to comment Share on other sites More sharing options...
Oddmanout84 Posted February 28, 2011 Author Share Posted February 28, 2011 The orange rustbucket keeps on giving. I still throw my vote in for patching the big horrible hole using the donor as a panel. Just seems to have the fewest possible scary issues involved. I remember the rust on the leading edge, are there any other issues? Looks like you trimmed it down, I thought I cut it longer. Nope, I didn't do anything more to it other than start removing the headliner. Quote Link to comment Share on other sites More sharing options...
subridersix Posted March 3, 2011 Share Posted March 3, 2011 I'd go to eastwood .com and buy a flanging tool, cut out the hole, flange the perimeter to stiffen the roof and weld in my patch. The flange will let you overlap all the way around without changing the roof line and keep your welds away from the edge so there is much less chance of burning thru. Quote Link to comment Share on other sites More sharing options...
Oddmanout84 Posted March 28, 2011 Author Share Posted March 28, 2011 I'd go to eastwood .com and buy a flanging tool, cut out the hole, flange the perimeter to stiffen the roof and weld in my patch. The flange will let you overlap all the way around without changing the roof line and keep your welds away from the edge so there is much less chance of burning thru. Thanks for the tip! A couple weeks ago I grabbed one and I'm in the process of cutting/flanging/welding today. I'll try to remember to post progress and snapshots of the process later. Quote Link to comment Share on other sites More sharing options...
darom Posted April 2, 2011 Share Posted April 2, 2011 What are your plans for drainage holes on each side at the top part of the hatch? My 76 came with the same sun roof monstrosity. I patched mine with a bigger piece of the donor's roof. Regards! Quote Link to comment Share on other sites More sharing options...
Snailed Posted April 8, 2011 Share Posted April 8, 2011 I would cut it about 8" in from all sides so it's easy hammer. Also, cut the corners with a nice radius, maybe 2-3", this will keep warping to a minnimum. Quote Link to comment Share on other sites More sharing options...
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