Body - Fibreglassing the Windscreen Frame

I have carried out the chopping of the roof and modifying the rake of the windscreen but I want to modify the firewall and cowl a lot more yet too. The problem is with all these cuts the body is getting quite weak, so before I cut the cowl out, I need to make that part of the car a bit more rigid.

The windscreen frame will help hold the door frames in place, but it too is weak as I dropped the windscreen down so that when the car is finished the wipers will go down below the bonnet line. To achieve that I had to narrow up the bottom of the screen so it would go down inside the pillars.

You can see here how the screen frame is down inside the door frame.

Doing this meant taking a bit out of the center of the frame at the bottom to allow it to pull in at the sides, just enough for the frame to slip down inside.

You can see in this drawing how I took a chunk out of the bottom centre of the frame to allow it to pull in.

To allow this to happen though I needed to relieve the top corners, so that when the bottom is pulled in, the relief cuts in the top corners can open up. You can see in this next drawing where I positioned these cuts and how they open up when the lower part of the screen is pulled together. I left some tabs (extra material) there so that the cuts wouldn't break right through.

So what I will do now is I will fibreglass the cuts I made in the windscreen frame as once this is back in and glassed into place it will provide a rigid structure between the the two door frames (aided by the timber braces I added earlier) that will hold everything to shape once the cowl is removed.

Anyway, here's what was involved in glassing the screen frame cuts.

Firstly I needed to lay the screen frame flat on a board so that it wouldn't be twisted out of shape. This is really important as the windscreen being 6mm thick glass won't bend so there is no way I can afford to have a screen frame that is not flat. It would not only end up with big gaps between the glass and the frame, but there is also the risk that the glass would be under tension and fracture.

Once the frame was laid on the board and I was certain it was sitting flat, the next thing I had to do was make sure when I glassed the cuts back together was to check that in addition to the screen frame sitting flat, that it was also square or in other words the frame when looked at from the front of the car would be even and not leaned over one way as that would look odd.

So what I did was add screws in each corner against the tabs I left near the cuts at the top corner of the frame. As I said before these tabs just ensured there was some strength adjacent to where I made the cuts. It turns out now they came in handy. I will call it planning but actually it was just good luck.

Then I needed to make sure I pulled the sides in evenly. I did this by letting the screen relax to its original shape and marked the line it followed on the board with some masking tape. Then I pulled the screen together at the bottom and checked how much it moved. It turned out that it pulled in about 12mm on one side and 8mm on the other, so I averaged that (10mm each side) and put another set of tapes in place to mark that. You can see both tapes below.

When I had pulled the screen by the right amount on each side, it lined up perfectly with the second tape when viewed vertically from above. In this next pic if you enlarge it (by double clicking on it), you might just be able to see a whisker of green tape right on the edge of the screen frame.

Now that it was in the right place I locked the frame in place by putting a screw against each side. The centre gap was now closed but pushed up to a peak, so I had to add another two screws to bring the frame down to form a nice curve.

Again I will call it planning....but it was just luck. The screws I used were nice and long so there was thread pressing against the fibreglass frame. This thread was handy for holding the frame down flat on the board, they acted like little adjustable teeth.

Now to fibreglass it all in place..... firstly prep some strips of fibreglass mat.....

Then mix up the resin and catalyst. I am using Polyester Resin and you mix about 3 or 4 drops of hardener/catalyst to each tablespoon of resin. That gives you a good 20 minutes or so to work with the resin before it starts to set on you. You can speed up the process by adding more catalyst, but I am no expert so the 20 minutes works good for me.

Now before getting underway, I added some gladwrap beneath the cuts so that I didn't end up gluing the frame to my board.

Then its kinda like doing paper mache. First brush on some resin.

Then place some mat.

Then soak it with more resin.

After a few layers, its just a case of letting it set.

Now I must point out here and THIS IS IMPORTANT. These are temporary patches until I have the body exactly as I want it. To do the final glassing of the cuts a bit more work is required as glassing straight over a cut like this would crack over time. I will explain the process for that in a later Blog when I start to glass up the roof chop, but for now, these temp patches will suffice.

Here is one of the top corner cuts glassed in.

And next day once the glass had hardened off I was able to unscrew the frame from the board and pop it back in between the door frames. Nice and square and fitted snuggly.