Screen Call

RS60 Windscreen History

From what I’ve seen the unavailability of specialised window glass kills most glorious scratchbuild dreams. You have to buy the original (how much does an original 250 GTO screen cost?) or design a car that fits the glass (so many Lancia Stratos windowed cars) or design a car with flat or no glass. Custom screens are a non-starter since Pilkingtons left Wellington.

My RS60 replica needs glass as well. The original 550 Spyder and later RSK had a low cut Perspex wind deflector. Legend has it that Mr Ferrari feared a walloping from the little Porsche screamer so he used his influence to ensure that the FAI 1600 race class specified a full size windscreen. Goodbye aerodynamic advantage – hello Ferrari horsepower. Even so the RS60 trounced the Testarossa 250 to win the 1960 Sebring 12hours.

Interestingly the RS60 has one windscreen wiper on the outside of the screen and another on the inside. That tells you something.

Pix 1, profiles

Options

My options ranged from expensive, a Porsche 356 speedster windscreen, to dim-witted, is it possible to sandblast a modern windscreen to size?

A low cut 718-style wind deflector was the only answer. The Hobby Car Manual requires automotive glazing with etched approval marks while a plastic wind deflector cannot extend higher than the driver’s eye line. Goggles it is and goodbye hopes for a roof. “So it’s just a toy then”, says my wife accusingly.

Perspex / acrylic is unacceptable because while it’s stronger than glass it also breaks like glass.

Polycarbonate/Lexan is stronger and bendier, but liable to scratching and chemical damage. Palsun is one such product in NZ while Makrolon has a hardened surface but is much more expensive. I approached PSP (5a Riddlers Crescent Petone) but they would only sell commercial quantities. Graley Plastic Supplies (71 Sydney St, Petone 04-570 0993) ‎were prepared to cut a small job from a supplied template.

DIY

I made a dodgy thick cardboard template. It has to bend like poly – don’t crease it. I purchased 2mm Palsun and Graley cut a slightly wobbly shape. My memory is that it cost about $120.

My aim was to cold bend the poly. I gather that polycarbonate absorbs water and its optical properties are damaged if it’s hot bent without hours of oven drying. This meant I couldn’t make a compound curve windscreen. It had be ‘developable’ i.e. can be unrolled to a flat sheet.

Strong and attractive A pillars were made from... wait for it …. chromed zinc alloy drawer handles fresh from Bunnings. Zinc alloys have come a long way from what my father calls monkey metal.

Pix 2, A pillars: from kitchen to Karussell

Polycarbonate is relatively immune from cracking and chipping along edges and holes. However, a cold bend puts a lot of tension into things. I clamped the screen back with plates NOT just bolts and washers. Unclamped, it’ll spring flat again. Two mm seems thin but the result is structurally strong. I got a glass-like edge with 400.

The bottom gap was shocking – up to 6mm – but this was easily hidden with a chrome/rubber wheel arch trim imported from Car Builder Solutions (local retailers were hopeless). Finally, I zipped it up with black polyurethane adhesive sealant.

Crackers

Now the tragic bit. Polycarbonate is verrryyy sensitive to solvents. It must be washed with a silk scarf wetted in baby’s tears. Silly me, I used toluene to clean Sharpie ink off the A pillar and the fumes, just the fumes mind you, wafted past the windscreen at its point of greatest tension. Instantly, a spider web of cracks appeared.

Pix 3, cracks. Stop holes have halted the cracks. The strength is still there so it is nothing a tacky decal can’t cover!

Swinging

Righto on to the side screens. These are 3mm cast acrylic from Bunnings. Jeepers you have to be careful. The first attempt took fright at my jigsaw and snapped like a carrot. Acrylic chips and cracks easily. One tip I heard was to use a blunt drill as new drills bite too hard. That’s easy, all my drills are blunt! I’ll fit polycarbonate side screens if the acrylic fails in service. I also read that you can flame finish an acrylic edge so maybe they’ll fail before the first drive!!

Here’s a trick. Awning extrusions make a great window frame.

Pix 4 Ulrich mouldings. Bung in the window, fill the gap with some grey adhesive sealant – good ‘un

The side screens swing on little stainless marine hinges and dinky flange screws from Anzor (great service) to produce a mini-door. Mirrors are mounted to the side screen because I couldn't bear to drill holes in my new paint job.

Pix 5, trim and fixing details

Done

Okay let’s step back and take a look. Not bad… and with cold bending, not all that difficult.

Pix 6 job done

Next Axles