Add style, structural integrity,...
Add style, structural integrity, and eliminate any chance of leaks by filling that gaping hole in your sedan's roof.
It's easy to forget that until 1937 automakers didn't have the appropriate size presses and technology to stamp out one-piece roof turrets. Rather, the roofs were made in three or four pieces and then assembled with welding and leaded seams. The remaining huge hole in the middle was filled with wood crossbraces, padding, a layer of chicken wire, with the top material made of an early vinyl material. Amazingly, these tops sealed quite well for the first 10 years or so, but as the products filling the hole deteriorated, the elements came pouring in, leading to stained mohair and more.
The donor skin is from an...
The donor skin is from an '80s-era Malibu station wagon that Larry Shoaf carefully trimmed out. The inner braces were also saved as they will be modified and used to support the skin.
Hot rodders have long been removing the fabric roof inserts and filling the roof with a steel insert. This provides a smoother, more modern appearance to the car and ends the chance of leaks forever. The early hot rodder's choice of sheetmetal was generally from a later model car that had all the right curves to match the car. Remember, the roof curves in virtually all directions so you must find a piece of metal that does the same. Filling the roof on a coupe is pretty simple because the hole is smaller so a smooth roof panel from a later car works well, but when you tackle a sedan the job becomes considerably larger. Larger sedan roofs involve a substantial amount of sheetmetal so interior bracing and stamped ribbing in the roof panel make the panel stronger and less flexible.
The long cut was made with...
The long cut was made with large sheetmetal shears, making two cuts this long will work those forearm muscles. After the trimming, the filler piece went outside for a quick sandblasting.
Warping the sheetmetal during the filling process is a major concern as is dreaded "oil canning," where the roof buckles up and down when you try to wax the car. Once again the proper curvature of the filling panel will help eliminate both of these problems, but it is safe to say the potential for these problems is significantly greater when you are filling the long roof of a sedan.
Luckily, street rodders today have MIG welders and access to a myriad of clamping devices that will help prevent any warping associated with the welding process and as you follow along with this story you'll see how to reuse factory roof braces from late-model cars to stabilized the filler panel and also provide mounting points for the headliner.
Before removing the inner...
Before removing the inner braces from the donor roofskin, Shoaf marked both the position front to rear and the direction of the brace. The braces were bonded to the skin with foam.
The roof being filled for this story is a 1935 Buick sedan owned by Scott Miller, and friends when it comes to filling a gaping hole in the roof they just don't come much bigger than this one. The work is being performed at Rodcrafters in Welcome, North Carolina, with longtime roof filler Larry Shoaf wielding the hammer and welder.
The roof insert and associated inner braces were salvaged from an '80s vintage Chevrolet Malibu station wagon. Shoaf bought the entire roof panel from the top of the A-pillar to the rear of the roof to ensure that he would have all the inner bracing and enough tin to fill the hole. The ribbed roof will go a long way to stiffening the large panel and add all-important style points to the job at the same time.
After laying the donor skin...
After laying the donor skin over the open hole in the '35 Buick roof it was marked from the inside and then trimmed 1 inch oversized in all directions. The final cut will be done later.
Like all good street rod modifications, the main ingredients seem to be patience and plenty of careful measuring, fitting, and clamping. This is a modification that many hot rodders can complete in their home shop. The Rodcrafters approach to roof filling brings with it some unique concepts that will help you get the perfect fit and contour.
In the end you'll have a sedan with a much stronger body as the filled roof brings with it additional structural integrity. Like any major modification it's best to be sure all your door gaps are correct before stiffening the body with a roof insert. Let's head out to the shop and get busy filling the long roof.