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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Re: Windshield brace

Post by tamnalan » Sat Feb 11, 2017 8:20 pm

I think I just get a little too worried about things like this. Maybe it's that my wife and I both still work and are empty nesters. I have a little extra cash. Maybe it's that I find McMaster Carr to be almost addictive. Nobody's windshield frame failed that I know of in any of the national MVPA convoys so far. Still, my jeep's frame is pretty old. Older than me I think, and I'm not young dammit.

I agree with your math, Chuck. The wind force I believe is against the windshield's projected area. I eyeballed my windshield slant and I think it's about 10 degrees from vertical. This would reduce the 8 sq ft by only a few %. Together with the drag coefficient, we should also consider the "pulling force" that the jeep top would impose on the windshield too. I'm not sure what that force is... maybe 100 lb intermittently if the top is buffeting at speed too. I conservatively think each brace will provide about 50 lb of force before starting to fail, so I added about 100 lb of total resistive force for the two braces.

Edit: Another thing to consider is the tubing fatigue life. I think we all were and am just adding it here for the record. These frames must experience thousands to hundreds of thousands of stress cycles. Here's an interesting article that measures fatigue life for similar tubing with butt welds. http://people.cst.cmich.edu/yelam1k/ase ... ion_28.pdf

If I were to put this problem to a students at school (I'm a teacher) I would expect them to reduce the forces to the moments applied to the base of the windshield frame in that area where the frame usually breaks. A moment is a twisting thing .. a torque in the physics sense ... a perpendicular force multiplied by the length of the "lever" measured from where the force is applied to a point of reference. If the moments applied by the wind and the jeep top sum to a number smaller than what the frame, the cowl, and my new brace produce, then I should have a reliable frame! Woo hoo!

Here's what I ended up with. Now I can close the windshield if I want to.

Image

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Last edited by tamnalan on Sun Feb 12, 2017 3:11 pm, edited 1 time in total.
Alan W. Johnson
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MB, 201453, "Lt Bob"
M-100, Sep 1951
MB-TD, Mar 2012
Ford 91C, 1939

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Re: Windshield brace

Post by W. Winget » Sat Feb 11, 2017 8:32 pm

You could cut holes in the top of the pipes and pour molten lead in giving extra strength to the frame. (repaint following that...)
Or insert a piece of solid stock within the frame uprights then weld the caps up...
1000 ways to solve a problem that really isn't prevalent.
But your solution is temporary at least without long term "bubba" mod of the vehicle, for that I applaud you.
V/R W Winget.

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tamnalan
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Re: Windshield brace

Post by tamnalan » Sat Feb 11, 2017 8:42 pm

Thanks - I confess that I've frankensteined my MB up a bit but I'm trying to stick to bolt-ons. I drilled holes to fit a set of canvas doors and a right-hand-side rear view mirror. Those doors were lifesavers on the AC12 convoy! There were some cold wet days. I had to put a right-hand side mirror on because my camper trailer creates a blind spot and I didn't feel safe making lane changes on busy roads.

My final mod will be turn signals. I'm going to repurpose the blackout lights for that. I hope the only "tell" for them will be the turnsignal switch.
Alan W. Johnson
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MB, 201453, "Lt Bob"
M-100, Sep 1951
MB-TD, Mar 2012
Ford 91C, 1939

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Re: Windshield brace

Post by Marty, SoCal » Sat Feb 11, 2017 9:16 pm

Alan,
Did you see the post on a mod to turn the reflectors into lights using LED's and spacers to allow them to fit behind the reflectors? It involved using spacers the same size and shape as the reflector bezels about 1/4" thick behind the reflectors with the backs off and LED lights fitted to them. I'm having trouble finding the post, it was a couple years ago I saw it here on the G. With the tiny surface mount LED's it might even be possible to fit them inside a standard reflector, with a little work.

Another post I did find was on the Dodge Power Wagon forum from a couple years ago and involves fitting lamps behind the reflectors to light them up:
viewtopic.php?f=56&t=249096&p=1459112&h ... r#p1459112
43 Ford GPW 92098
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Sold: 61 CJ-5, 41 T207 WC-1 Dodge closed cab pickup
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Re: Windshield brace

Post by tamnalan » Sun Feb 12, 2017 8:39 am

Thanks Marty - that's a good idea. They would be much more visible than my blackout light method.
Alan W. Johnson
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M-100, Sep 1951
MB-TD, Mar 2012
Ford 91C, 1939


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Re: Windshield brace

Post by dfast » Mon Feb 13, 2017 3:22 pm

One more thread about led reflectors, complete tail unit placed within reflector bezel.
viewtopic.php?f=144&t=251573&start=15
GPW 268625 45' with MB tub 2071421S
CJ3B 1968 ex Military
Restoration viewtopic.php?f=136&t=240027

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Re: Windshield brace

Post by tamnalan » Mon Feb 13, 2017 7:03 pm

Thanks! What a nice GPW! I loved it.

That's a good idea with the reflectors. I just may do that! I'm now thinking of leaving the stock system alone, which I should have thunk in the first place. :?
Alan W. Johnson
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MB-TD, Mar 2012
Ford 91C, 1939

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Re: Windshield brace

Post by tamnalan » Wed Feb 15, 2017 7:53 am

It's hard to find 6 volt flush mount LED assemblies that will fit a reflector. This fellow will make them: http://www.lambertenterprises.com/
Alan W. Johnson
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M-100, Sep 1951
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Ford 91C, 1939

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Re: Windshield brace

Post by Chuck Lutz » Sun Feb 19, 2017 12:49 pm

Wander down to the 1/4 ton Trailer Forum and do a search using "Japanese". I think you will find they made a variation of the standard bucket that is baffled off. Using that set up you can use Stop and Tail on the top bulb and Turn Signal on the lower bulb...you are replacing the original lamps with 6 volt bulbs that fit the same socket.

You might find some of these:
Trailer Bezels - Japan.jpg
Trailer Bezels - Japan.jpg (112.34 KiB) Viewed 631 times
Trailer Buckets - Japan.jpg
Trailer Buckets - Japan.jpg (143.95 KiB) Viewed 631 times
If you do the grill BO lights as turn indicators, get some of Paul FitzGerald's LEDs for them....2-3 times as BRIGHT.
Chuck Lutz

GPW 17963 4/24/42 Chester, PA. USA 20113473 (USA est./Tom W.)
GPW 108552 4/17/43 Louisville, KY. USA 20371278 (DOD est./Tom W.)
Bantam T3 4582 10/29/42 USA 0173499 (est.)

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tamnalan
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Re: Windshield brace

Post by tamnalan » Sun Feb 19, 2017 1:02 pm

Thanks Chuck! I contacted Paul about this project. I have some of his LED bulbs. They are very good.
Alan W. Johnson
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MB, 201453, "Lt Bob"
M-100, Sep 1951
MB-TD, Mar 2012
Ford 91C, 1939

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Re: Windshield brace

Post by Marty, SoCal » Tue Feb 21, 2017 10:46 am

Maybe a pair of these Toyota custom reflector replacements could be fitted to reproduction reflector housings, they are 2-3/4" diameter and have a brake and running light function with a reflector lens. $23 a pair!

http://store.ijdmtoy.com/Toyota-Sienna- ... 16.htm#top

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43 Ford GPW 92098
53 Dunbar Kapple M100
Sold: 61 CJ-5, 41 T207 WC-1 Dodge closed cab pickup
MVPA #8266
USMC Tanker (1811, 1812), 85-93
ASE Automotive Master tech, former Chrysler-Jeep Level 4 Mastertech, CA state EA smog license

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Re: Windshield brace

Post by tamnalan » Wed Feb 22, 2017 6:52 am

Those would be perfect if they came in 6 volts. A 12-volt inverter might work to power them.
Alan W. Johnson
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MB, 201453, "Lt Bob"
M-100, Sep 1951
MB-TD, Mar 2012
Ford 91C, 1939

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Re: Windshield brace

Post by Marty, SoCal » Sun Feb 26, 2017 8:09 am

Most LED lamps I've tried will light with 6 volts, just slightly dimmer!
43 Ford GPW 92098
53 Dunbar Kapple M100
Sold: 61 CJ-5, 41 T207 WC-1 Dodge closed cab pickup
MVPA #8266
USMC Tanker (1811, 1812), 85-93
ASE Automotive Master tech, former Chrysler-Jeep Level 4 Mastertech, CA state EA smog license

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tamnalan
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Re: Windshield brace

Post by tamnalan » Mon Feb 27, 2017 3:03 pm

I'm going to give those Toyota reflecter LED's a try, Marty. I called them and they said it might work. Free shipping. Woot!

Full report in a few weeks...
Alan W. Johnson
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M-100, Sep 1951
MB-TD, Mar 2012
Ford 91C, 1939

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Re: Windshield brace

Post by tamnalan » Tue Mar 07, 2017 6:55 pm

So I got the Toyota lights. The good news is that they fit in a reflector housing really nicely! The bad news is that they work but look pretty anemic on 6 volts.

I already have a small 12 volt converter in my MB to power a phone charger or GPS unit. It puts out about 5 watts of continuous power, which might be enough for LED lighting. I'm going to try it.
Alan W. Johnson
_______________
MB, 201453, "Lt Bob"
M-100, Sep 1951
MB-TD, Mar 2012
Ford 91C, 1939

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