Windshield brace

1941 - 1945, MB, GPW modifications, sugestions, and ideas, official MWO's and unofficial WWII field mods NO EBAY or COMMERCIAL SALES.
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tamnalan
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Windshield brace

Post by tamnalan » Sun Feb 05, 2017 2:10 pm

I've never felt comfortable with the buffeting my windshield suffers at speed. I'm experimenting with some sort of brace that will be easy to take on/off and won't stick out much. I would use it for convoys / highway trips. Here's what I have so far. What other ideas are out there?

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Re: Windshield brace

Post by Joe Gopan » Sun Feb 05, 2017 3:57 pm

Does it reduce the buffeting?
Look up some of the Korean War era photos of MB's in Korea, note the rods used to brace the windshields.
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Re: Windshield brace

Post by tamnalan » Sun Feb 05, 2017 4:14 pm

It won't reduce the buffeting but it should reduce the stress on the outer windshield tubing bend. I've found that opening the windshield a bit helps with the buffeting.

I've seen some old photos where a piece of wood or bar stock was fastened to the same two points I'm using. I'm going to try a shorter cord that wraps around the windshield tube at the windshield's lower corner.
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Re: Windshield brace

Post by Rod Rushton » Tue Feb 07, 2017 11:48 am

Whilst not exactly a brace, on the windshield of my AC Cobra it had Plexiglas deflectors, without which the buffeting was quite severe.I also incorporated these on my pre-war MG midget to great effect. This is a problem endemic to all vehicles with flat windshields.
Most modern sportcars also have a mesh screen behind the driver and passengers heads to shield them from buffeting by the wind.
Whilst I am not advocating these mods should be incorporated into Jeeps, these are others' solutions to the problem.
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Re: Windshield brace

Post by tamnalan » Tue Feb 07, 2017 1:52 pm

Thanks Rod - you sure have some nice cars!
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Re: Windshield brace

Post by JIMN » Thu Feb 09, 2017 1:27 am

I don't think I have ever experienced in a jeep what you are trying to solve, or maybe I just drive slower.
Are you saying the windshield frame is flexing, or are you saying there is an annoying deep pulsating/thumping sound of the wind? or both?
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Re: Windshield brace

Post by Joe Gopan » Thu Feb 09, 2017 4:38 am

This is an MB/GPW problem exacerbated by the loose fitting A-3216 Top with no rods to stiffen the sides. The stronger CJ-3A and M-38 Windshield cured that. Similar CJ-2A had rigid rods attached to bows and windshield frame that prevented that.
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Re: Windshield brace

Post by W. Winget » Thu Feb 09, 2017 1:27 pm

I always ride with the windshield opened about 3-4 inches, (enough to still open the hood without it ever hitting the windshield) this allows air to flow through and not have wind hitting me behind my head as much when I drive.
Much easier than adding devices, open the windshield frame a few inches and it should reduce the stress on the whole windshield frame your stressing about :D .
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Re: Windshield brace

Post by tamnalan » Thu Feb 09, 2017 2:10 pm

Thanks, yes I already do that.
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Re: Windshield brace

Post by Joe Gopan » Thu Feb 09, 2017 3:12 pm

Don't swallow any hornets or June Bugs. :wink:
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Re: Windshield brace

Post by Marty, SoCal » Fri Feb 10, 2017 11:11 am

Looks like a simple solution to strengthening the windshield frame to me! Especially if you drive or tow with the top on at higher speeds it should help

Having the windshield open 3-4" at the bottom really does help the buffeting and air wrapping around and hitting your head, No bugs for me, and I often drive at 60 mph + with my overdrive.
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Re: Windshield brace

Post by Chuck Lutz » Fri Feb 10, 2017 12:27 pm

Hmmm...just how much "force" is exerted against that windshield anyway? To convert wind speed to pressure I think it works like this:

1) Square the wind speed (I used 45 mph for this exercise) 45 x 45 = 2025

2) Multiply result by 0.0027 to get pounds per sq ft. 2-25 x 0.0027 = 5.47 per sq ft

3) Windshield is 8 sq ft so...5.47 x 8 = 43.74 pounds of pressure against the windshield at 45 mph.

4) I suppose you could get buffeted by a semi going the other way at 65 mph and then get 92 pounds of pressure against the windshield.

5) If you were driving at 45 mph into a 20 mph headwind that would be the same result....92 pounds against the windshield.

6) in either scenario, divide that by the TWO arms on the windshield and you get maybe 25-50 lbs on each arm...roughly the weight of a suitcase allowance at the airport these days.

Personally I believe that people getting in and out of the jeep using the windshield as a grab handle exert a greater pressure than the wind does. We had to HEAT the arm cherry red and apply maybe 20-30 lbs of force using a 4' lever to bend the frame when we straightened the arms on a couple windshields.
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Re: Windshield brace

Post by Marty, SoCal » Fri Feb 10, 2017 1:42 pm

Co-efficient of drag needs to be added, multiply by 2.0 for a flat plate, probably a little less due to the angle, though. If you really want to get into it, you need to account for the wind gusts and height above the ground.

http://www.wikihow.com/Calculate-Wind-Load
Last edited by Marty, SoCal on Sat Feb 11, 2017 5:28 am, edited 1 time in total.
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Re: Windshield brace

Post by Joe Gopan » Sat Feb 11, 2017 5:24 am

An A-3216 Top at 45-50 MPH is rough on an MB/GPW Windshield Frame, one can see the flexing in the cowl area. The windshield frame will let go before a properly made canvas with secure grommet installation.
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Re: Windshield brace

Post by Marty, SoCal » Sat Feb 11, 2017 5:40 am

Another worry is how much rust is inside the 70+ year old frame tubing, hidden from view :?
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