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1931 steve 04-11-2007 07:28 AM

Chop Top question
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In the picture below you can see the lay out tape for the top to be chopped, but none of the lines are even with each other.
Are they a reason for this? Why not just do a straight line all around the top?


35WINDOW 04-11-2007 07:43 AM

Steve, I believe the reason is that you want to pick the places that the areas NOT to be chopped will fit back together with the least amount of pie cutting-you want the Top and Bottom to match. I'm just finishing my first Chop, and I clearly see things much differently than when I first contemplated it.

If you just chopped it around in a straight line I think there would be a bunch more fab work (even though this type of Body is one of the easier ones to Chop)-

MARTINSR 04-11-2007 08:13 AM

Not having the lines line up has no effect at all, or it has lots of effect, just as you wanted. It really depends on what car you are chopping and your plans of how to accomplish the task.

On the body you see the "B" pillar (middle post) is probably being cut up higher so the cut will miss the upper door hinge. On the front post ("A" pillar) it is probably down lower because the post is the same diameter around at that area but tapers down smaller or something up higher.

On some cars you may even want the cut to be at an angle from one window to the next. It all depends on where the parts are going to line up WHERE you cut it.

A top doesn't come STRAIGHT down when you remove a portion of the posts. On some cars, yes. A Ford Model A for instance, the top comes STRAIGHT down (all models but the 31 Vicky) Cut 3 inches out of the posts and drop it, it doesn't matter much where you do it, just cut the roof off, cut 3 inches off the post and drop it back down, and you everything will line up. The windshield posts do have a taper WITHIN them that you have to take care of but the post in relation to the others is perfectly vertical. So the back side of the windshield post at least is perfectly vertical.

On the Model A it is like shortening a cardboard box. Just cut a strip out and the box is smaller.

On other cars, it is more like cutting a strip out of a ice cream cone. When you remove the strip the top piece won't fit onto the bottom piece. Almost every single body has this effect to some degree, some worse than others. So even a super simple body like a truck cab where you know there is a slight windshield rearword post lean, there is also a lean on rear cab as well as the front leaning IN from the sides. Sometimes a cut on one post five inches up from the bottom would allow the roof to come right down and mate with it's new location. While that same car may need another post cut eight inches up from the bottom for THAT post to line up.

Hope that explains it for you.


1931 steve 04-11-2007 10:37 AM

Thanks guys, I will be chopping the top o my 31 Model A when it comes time.

So it makes no difference on a Model A Ford where you cut the top off at?


MARTINSR 04-11-2007 07:58 PM

I like to cut the front post high, then when the top is off cut DOWN into the post right at the front and remove a small pie piece so the front will lean back a little and thin the top of the post to match the top piece. You will see what I am talking about when you get there. Cut find the middle of the windows and then measure out up and down half the distance you want to chop. That will put your cut out piece right in the middle.


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