SPF GT Window Repair / Mod

[Lynn Miner]

The early SPF GT40's used counter sunk stainless steel sheet metal screws to hold the windows and light covers on. These were poorly done because the holes were too small and the counter sunk hole took away all the “meat” for the screw to grab and caused the windows to crack under significant swings in temperature. Where I am in NE Washington State, temps in the summer can be 100 degrees and in the winter -25 degrees. The coefficient of expansion of this plastic is such that the windows move with temp extremes. After lots of whining to the factory (by me), they changed the screws to button head screws and drilled the holes slightly bigger to allow the window to “float”. If you have one of the early cars (less than around P2180 or so), here is a solution. Some like it, some don't. As for originality, I have found several references where they used the same technique in the 60's. Of course you could also simply get the proper screws but the countersink is still in the plastic making the holes weak.

Firstly, I removed all the windows and covers. I drilled the holes oversize by about 0.050 inches. Then I purchased #6 black plastic “Deco” washers. These are counter sunk on top and flat on the bottom. This allows for much better load distribution of the screw head. After having done this.....no more cracks. These washers are available from McMaster Carr.

If your windows are cracked or get cracked, go to a local plastic supplier or plastic fab shop and get a small can of methylene chloride. A 4 oz can should not cost more than $3. This “glue” is very viscous, more so even than water, so the best way to apply it is with a syringe. Lay the two pieces together along the broken edges and place the needle of the syringe into the crack or break. Very gently push the plunger and the glue will seep into the crack with capillary action. Hold the pieces in place for a few seconds and then release. The glue sets almost instantly. It only takes a small drop of glue to fill the void. When I say gently, I mean GENTLY, a single drop of this glue will repair a crack 2-3 inches long. If you squirt it out it will wreck the window. Be very careful not to get the glue on your fingers or on the window in a spot other than where you want it to go. It will “frost” the plastic everywhere it goes or touches. If done properly, the crack will disappear.