I am building my first street rod. I have built muscle cars before but this is the first rod. Anyway, it is a 35 buick and I have transplanted a power sunroof top into the open top of the car. My question is should I weld this thing in solid all the way around? Also the original top has small rectangles all the way around where the nails went through. Should I weld all of these up? I was thinking it might be better to stich weld the top and leave the rectangles open so the filler can squish through and grab a hold. What do you experienced guys think?

It has been my experience that it is better to weld the piece in solid. Any gaps or opening do let the filler get a good bite, but, on a roof, there is a lot of seasonal heat changes and the filler will either show up badly and/or crack anywhere it is not supported by welded sheetmetal.

Thanks, I'll need to buy 50 lbs of wire. This car is a four door sedan and has 4 acres of roof. I was thinking I should probably use tiger hair filler for more strength on the roof.

If you're going to use filler on the roof the seams will definately need to be completely welded, otherwise the expansion and contraction will crack your filler. Get your metal work as close to perfect as possible. Try to keep your filler to a minimum and apply two to three good coats of epoxy to the bare steel before applying your filler.

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Great idea, the epoxy will make the fiberglass or body filler more flexible and less likely to pop lose or bubble from contraction and expansion.

What epoxy do you recommend?

If you want to save a few bucks and still use a quality epoxy I would suggest using PPG EPX-900 out of the light industrial coatings line. It is nuetral in color but your jobber can tint it any shade of grey if prefered. CRE-CT is another good product but very thick. DP-LF is more expensive but I don't see any benifits. There are many epoxies available these days. Valspar, Matrix, Transtar all offer decent products. Dupont and Akzo Nobel also carry good products. Akzo Nobel's U-tech line of epoxies are very good. Southern Polyurethanes has been brought up on this site as having a good epoxy but I haven't tried the stuff yet.

Just make sure your metal surface is very very clean before applying the primer. After cleaning you should be able to wipe the steel with a dry white paper towel and the towel will remain clean. Allow proper flash time between coats. And let it set a minimum of overnight before applying your filler. I would use Evercoat's Everglass or Glass Lite over your weld areas and anywhere the filler will end up at or near 1/8" thick, then skim it with a thin coat of Rage or Rage Gold or my favorite Rage Extreme. I know I sound like a salesman for Evercoat but I really do like these products- they never fail me. Stock up on sandpaper. Bob