windshield / deflector thickness

[Jamesbe]

Hi I've been trying to make a wind deflector / windshield for my PFM.

First one was doing great until I drilled a hole for a rivet and it cracked... not near the hole in a totally different place... frustrating.

It wasn't bad so I used some packing tape to fix it, but decided to make another one.

Anyways, second one was way worse, it cracked in 3 places when I was cutting it with the jigsaw. I have it clamped on a piece of plywood to avoid vibrations etc.

Either I bought really crappy plexi, or maybe it's too thin? It's optix acrylic apparently about 3/32" thick

Thoughts? Thicker material? Or maybe buy some lexan? DIdn't think a little piece like this was going to be a pain or need to be super strong.

[mikey]

I used lexan on my PFM. Can’t recall thickness but was either 3/32 or 1/8”. Never had to replace it. I only attached it with 3M push lock strips.

[Thomas Wirtz]

FWIW,
I just had a new windscreen made by Aircraft Windshield in California for my 1978 Super Vee.
The original was cracked when I bought the car and was 1/8 thick. Aircraft Windshield suggested I use the standard 3/16 thick material.
A little thicker material couldn't hurt.

http://www.aircraftwindshield.com/

[Steve Davis]

I used a piece of flexible black abs plastic (~1/8"?) that I found lying around my shop. Trimmed it to about 2.5 inches wide and maybe 8 inches long (didn't measure .. just guessed ) Drilling it was easy since it was 'pliable' anyway. I put it in my vice lengthwise and bent ~half of it up, then slit the other side in 3 or 4 places so I could form an arc. Then held it on my cowl and marked it for drilling to hold it's shape against the wind. After installing, I mixed up some abs 'goo' and put some spots along the bent seam to stiffen it a bit. Seems to be working great after 4 races and a couple of test days.

[Jamesbe]

Thanks.

Mine certainly needs to be clear as I'm very low in the car.

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[JHerscher]

When I had my FF I used clear 1/16” lexan. Cut with tin snips (the cheapo yellow-handled Wiss snips you can get at Home Depot). As I recall the edge was nice enough that minimal filing was required. I think the acrylic I found was too brittle.

as the phrase goes, YMMV.

John

[DK540]

Gotta be Lexan.

DK

[Jamesbe]

Sounds like lexan is key. Thanks

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[Nardi]

Maybe modify an old face shield as a wind screen?

[Jamesbe]

Needs to be 16x5 inches.

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[mikey]

By the way, if you haven’t had one before make one that you can adjust the mounting height or make a couple in different heights. You will find a sweet spot that gets the air smoothly to the top of your helmet.

[10rmotor]

If you have access to a sheet metal shear that will work too. I believe there is a different angle on drill bits made for drilling acrylic or lexan to minimize cracking.

[Jamesbe]

The drilling didn't crack it. Just holding it did. Very odd.

It's also cold in my garage so possible the cold plastic was just too brittle.

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[pacratt]

Always Lexan...NEVER Plexi (too brittle).
I've used 1/16" (.062") Lexan for windscreens on FV's without fail.
Unless there are specific rules for thickness, that would be my choice.
Glenn

[Jamesbe]

Sounds like a plan. Will order a small piece, looks like I can get 2 windshields for $15 ish.

[grapefarmeral]

Thanks.

Mine certainly needs to be clear as I'm very low in the car.

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Stevan Davis has super powers and can see through black ABS....

[Steve Davis]

It's a gift. :-)
Steve

[t walgamuth]

If you wan to shape the plastic put it in the oven. At 300 degrees the plastic becomes like raw pizza dough. At that point you can put over a mold made from cardboard and when it cools off a bit it becomes rigid again. If you use a saw on it like a jigsaw you must not go too fast as it will get hot and gum things up.

I made a rather elaborate front screen/fairing for my BMW about 40 years ago. It came out pretty well. I positioned it so I just looked over it. The air deflected over it and it was good in the rain too.

On my Lotus D mod I made a deflector of aluminum, about 16" by about 4" and attached it with pop rivits. it was a bit crude but did the job. It deflected the air away from my face and I positioned it so I looked over it. ... perfect.

[kea]

I use a small soldering iron and burn a hole though it for fasteners.

[ChristopherBernard]

Lexan can also be bent in a brake to form flanges or tabs for mounting.