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Windshields - Making Your Own

I fabricated the windshield from a 24"x24"x1/8" piece of Lexan (polycarbonate) sheet.

I removed the stock windshield and clamped it to my Lexan sheet to trace the bottom shape and holes. For the top edges, I free-handed the inward slope and corner curves.

I then cut out the pattern with my saber saw using a fine tooth blade, drilled out the holes, smoothed all the edges with some 220-240 grit sandpaper then installed the new windshield on the bike.

After cutting and drilling the Lexan, but before peeling off the protective paper, I test installed the new windshield. Once in place, I traced along the inside edge of the fairing where the windshield met. Remove the windshield. Using an Exacto knife, I lightly cut through the protective paper along my mark, peeled off the paper below the mark and applied a good coat of black spray paint to the inside of the windshield. Once the paint was dry, all the protective paper was removed and the windshield installed for the final time. The black painted portion, matching that on the stock windshield, hides the ugly innards that would otherwise show through.

Total cost = $16.00
Total time = 1 hour

Result: a custom height windshield that eliminated the turbulence and noise of the stock shield. I am very happy with the results.

And some tips from Jim Theaker

Re heat drilling, you have to be VERY careful.  Without going into the chemistry of polymers, depending on the type, you can change the structure by the application of a temp as low as 50C and the resultant structure is actually very brittle and very crack prone.  I believe for Lexan this embrittling temp is about 200C.  I could not find the drill speed for Lexan in my old machinists hand book but it is slow and the feed rate is even slower.  The drill bit must be sharp, read almost new and I also know that in our shops they often put water on it to minimize stress cracks while drilling.


Here's a little bit of informative discussion that followed Steve's original post on the Delphi forum:

One Q: How did you form the curve? I mean the curve that has the sides further to the rear of the bike than the center of the shield....

The curve came naturally as the Lexan was screwed to the fairing. Started with the center screw and worked out to the edges. The 1/8" thickness allowed it to easily conform to the curve, yet has plenty of stiffness that there is no flexing or buffeting at any speed.

The ideal way to do this is with heat. When I did one of these last year, I took a piece of 2x8 and nailed 'stops' onto it to hold the plastic in the approximate shape it would have on the bike. The wood goes across the shield on the back side, with the sides tucked against the stops.
I then put this in a 200 degree oven for about 15 minutes until it had well and truely warmed, but not melted or burned. When I pulled it out, I was concerned that it looked a little foggy, but it cleared up when it cooled. I remember pulling it out early on the first attempt and having it straighten right back out when I removed it from the wood. Better to have to do it again than over-cook the plastic.

I think this process eased the stresses and allows the shield to be unflexed in its natural position. I will do it this way again if I make another shield.

Where did you buy the Lexan? We have a Lowe's in town but they only have the Plexiglas. I think that would scratch too easily. Any suggestions?
You are right, the Plexiglas from your local home improvement place is too fragile. I think it is more like Acrylic...think starburst cracking around over tightened Rifle shield screws, only worse. Lexan is pretty much bullet proof. (In fact in 1"+ thicknesses, it is used for bullet proof uses.)

I got my Lexan (polycarbonate sheet) at a plastic supplier in the Dallas/Fort Worth area. Check your yellow pages under "Plastics." Another source is McMaster-Carr, a mail order industrial supply house. I checked their catalog and they offer a 24"x24"x1/8" "Abrasion resistant" polycarbonate for about $34. They also have regular polycarbonate sheet in the same size for $13 and some change. I used the "regular" stuff and am happy with it.


 

The windscreen is homemade from 1/8" Lexan (cost $12.00) & black edging is from J C Whitney.

Made by Norm Gregoire, New Bedford, MA

Article By: Steve Yarbrough

August 2001

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