There's no two ways about it, a customized classic truck with a chopped top is more than just plain badass, it's as cool as it gets. But just like a new tattoo, it's the ultimate commitment with no going back, so it's best to get it right the first time. Sure one can cut off their arm or buy another truck, but who wants to do that?
Although written in the second tense, the actual work in this story was done entirely by Carmen Porco alone as he chopped the top on his Big Window '57 Chevy. Considering this was the first top Carmen has ever chopped we have to give him props for really taking his time and discovering some really good tips that we could pass on to CCT's valued readers. There are two common ways to chop a top, one is to bend the posts to meet without stretching the roof, and the other is to stretch the roof to realign with the stock glass dimensions. Carmen learned from a professional glass guy that bending the posts is the wrong way to go about it, unless one doesn't care if they can put their windshield and windows back in. Next, armed with the knowledge that the roof must be stretched to fit properly, Carmen chose to fabricate new sheetmetal pieces to fill the gap. Back in the old days when good roofs were plentiful, guys would cut the filler pieces needed from a donor truck and then weld them in. Old or new sheetmetal, the best way is to flange the filler strips and weld them in instead of trying to butt-weld the roof back together. The next hot tip, is to take your time and don't allow a lot of heat to build up. Once the roof's metal has been overheated and warped, its takes a skilled bodyman to repair the damage. So there you have it, don't bend the posts, don't butt-weld, and never tattoo a girl's name on your arm unless you have two or three spare arms.
Careful measurements were...
Careful measurements were taken at each window opening to determine the stock window openings. After the cut these measurements should be exactly 2 inches less
A position on each post is...
A position on each post is located that has parallel sides. The 2-inch area to cut is marked.
Bracing the cab lower section...
Bracing the cab lower section by tack welding in struts is essential to keeping the cab from springing (moving) out of shape.
We choose a Sawzall to do...
We choose a Sawzall to do the cutting, but a hacksaw, cutoff wheel, or plasma cutter will work just as well. The top is being held in place with a cherry picker.
The cherry picker makes the...
The cherry picker makes the job much easier for one person.
Once the top was removed the...
Once the top was removed the last cuts were made to the posts.
Next the top was brought back...
Next the top was brought back and placed on the cab to see how well the posts lined up. It can now be seen the top left to right has become narrower than the cab at each corner.
However from the side, the...
However from the side, the posts seem to almost line up. We determined that the best approach would be to section the top front to back and then fill in the gap. We could have opted for back-cutting the post and realigning them but this would have created more issues with the glass.
Next we checked the dimensions...
Next we checked the dimensions again, and they were exactly 2 inches less.
Now with the top removed we...
Now with the top removed we marked the center line both inside and outside.
Since we planned on keeping...
Since we planned on keeping the dome light we needed to remove that section and replace it later.
The cutoff wheel worked great...
The cutoff wheel worked great to cleanly cut the top in half.
Next to test-fit the top....
Next to test-fit the top. The tabs worked wonders with lining up the posts.
Finesse in aligning the posts...
Finesse in aligning the posts and then plug-welding the tabs to join the posts together.
With both sides on, the gap...
With both sides on, the gap in the top is plain to see. We used more steel braces to hold the top in place
A C-Clamp was used to hold...
A C-Clamp was used to hold the post in perfect alignment before welding. Notice we used plug welds to bond the steel tabs to the post first, then welded it up. Notice the bracing holding the top up.
A pneumatic flanger from Eastwood...
A pneumatic flanger from Eastwood made short work out of the next step. We used 18 gauge CRS as filler for the gap in the top, then chose to form a flange on each side. This made it easier to fasten it to the top and added a little more rigidity to the sheetmetal.
A filler strip was bent to...
A filler strip was bent to conform to the shape of the door jambs and then to prevent warping, slowly welded into place.
Kleekos were used to hold...
Kleekos were used to hold the filler panel in place and then very carefully the plug was spot welded in place. Slow is the operative word here as the roof panel is rather thin and will warp easily with too much heat.
A piece of steel pipe made...
A piece of steel pipe made a nice mandrel to shape the filler strip areas to conform to the curvature of the roof.
Once the correct curve was...
Once the correct curve was obtained, the filler strips were once again checked for fit, and then installed into place from underneath the roof.
Things look pretty close to...
Things look pretty close to done here, but there was still a lot of grinding and shaping left to do.
Thanks to moving slowly and...
Thanks to moving slowly and not allowing the heat zone to expand, there was no warping after the roof was welded in. The next steo was to grind. The next step was to grind these welds flush without creating too much heat and warp the roof.