Open Windshield Driving

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Travelfix
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Open Windshield Driving

Post by Travelfix » Wed Mar 06, 2019 6:53 pm

Not sure if this has ever been addressed before but just in case it hasn't, how about a little input on the subject.

"Driving a military vehicle with the windshield in the open position" From 1/4 tons all the way up to the big ones, most military vehicles have windshields that are capable of opening or swinging out for air ventilation. We've all done it BUT at what speeds. Certainly crawling along in a parade or driving down an old dirt road at 5 to 20 mph is acceptable but what about higher speeds?

What about driving on a paved secondary road at 40mph or higher with the windshield fully extended or opened? Is there any protocol or AR on this? I've always felt that driving with the windshield open fully, at too high of a speed may cause an updraft that could potentially flip the windshield up and over the cab, tearing it from it's hinges and causing harm to another motorist.

I recently viewed a video of a 1 1/2 ton traveling on a highway with the windshield fully extended. I didn't see the odometer but I would suspect 40 - 45mph by the looks of it. A windshield partially opened would have quite a bit of wind pressure on it but a fully extended windshield would have almost no wind pressure.

What's your take on this?

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Re: Open Windshield Driving

Post by wc56daveyboy » Thu Mar 07, 2019 6:13 am

I usually have my 1/2 ton closed cabs windshield partially open all the time whenever the weather gets above 70

Just a crack allows in enough air to make the cab cooler

Above 80 degrees and I open it up another 1" or so and the cab really gets the heat evacuated fast, as long as your moving that is!

Now the question of a fully open windshield all the way up and locked?

Done that but at low speeds only.

Had it up about 1/2 way once, because it was rather hot (100 degrees) and pretty darn near mandatory for the few miles slow driving of dirt road out of my neighborhood.

Once reaching the highway I didn't stop to adjust it closed a bit. having it open that far caused a multitude of flying bugs hitting my face.
That and the wind and dirt coming thru make it less than safe. I had dirt blown into my eyes while driving that way. Not safe.
Nor is it actually fun as the wind coming thru that open windshield causes as you say turbulence in the closed cab.

But that's a closed cab. And kinda necessary to open them windshields a crack in a closed cab in hot weather or you'll cook inside that metal can like a turkey in a roasting pan otherwise!

I'm pretty sure when I lived I Texas you COULD drive your jeep with windshield completely folded down on the hood BUT you were required to wear eye protection. Most people wear sunglasses anyway due to the sunlight so I guess safety concerns are met with sun glasses
Last edited by wc56daveyboy on Thu Mar 07, 2019 9:35 am, edited 1 time in total.

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Re: Open Windshield Driving

Post by Ben Dover » Thu Mar 07, 2019 6:37 am

Driving with open windshield is not legal in all states. MV'ers do enjoy it tho.
Gotta be careful as passengers and the curious may use the arms as grab handles to climb in to the Jeep (or any MV).
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Re: Open Windshield Driving

Post by Travelfix » Thu Mar 07, 2019 6:49 am

Thought that as long as the driver is wearing eye protection it was OK

What I was really looking for was whether the wind entering through a fully extended or opened windshield, would cause an up-draft and potentially rip it off it's hinges. I'm thinking of answering my own question with a YES!!

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Re: Open Windshield Driving

Post by Ben Dover » Thu Mar 07, 2019 6:55 am

Haven't seen that happen, big worry is bees.
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Re: Open Windshield Driving

Post by W. Winget » Thu Mar 07, 2019 9:01 am

I think it's only illegal to have the window down, not open (in some states)
I personally always drive with it cocked out about 6 inches. this I find is about right to get the back air flow from beating on my bald head, provide fresh air for cooling and let the June bugs and bee's impact the glass before falling down and being blown across the lap VS in the face.

Now I've driven with it down with and without glasses, usually only at slower speeds without glasses, but those bugs are hard to dodge at higher speeds, even with goggles.

Funny related side note: A CHICOM company sold a cheap looking metal (art) copy of a 3/4T Command Car through odd ball places like knife dealer companies and such and surplus dealers a few years back. It was sort of above the level of those sparkplug metal wire structures in detail...crap...but it had OD, and markings and some details. I noticed a few details that were familiar to MY Dodge...starting with the canted open windshield, a grab bar above the rear seats, the "VXIII and HQ6" bumper markings (painted on for the 50th anniversary of the end of the War 'pass in review' we did at Fort Bragg), and then on the side "lil Bear!" painted on...a nickname I had given my Wife as she can sometimes be roused like a bear...and had painted on the side of my vehicle after we were married....

Point was they had downloaded an on-line photo of mine from a show and made ?? several hundred ?? of these to export around the World? I had to buy one for $44 just to have. Windshield open at an angle.
Too bad they mistook the pioneer rack curved shovel on the back trunk as a second winch (drum) and made it with a winch mounted into the trunk, but neat model/art piece either way even if it was crap.
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Re: Open Windshield Driving

Post by D.R.H. » Fri Mar 08, 2019 6:49 pm

I have driven my 1st. Chevy all over So. Cal. with the windshield open on surface streets, occasionally on the freeway for short jaunts. Summer or Winter it didn't matter. I like the wind in my face. I wasn't ever stopped by an L.E.O. for it, had been looked at frequently, but that's it. I did consume a Honey Bee once driving through Angeles National Forest. I wasn't stung, but it did taste like Sage brush though. :)
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Re: Open Windshield Driving

Post by forestry4evr » Sat Mar 09, 2019 6:07 pm

I have driven with my G506 windshield wide open at high speed (40-45) on many occasions. I too was concerned about the sail effect of the assembly. It doesn't seem to buffet much, but I feel it is just too much wind to be what I would consider fun. In 10-25 mph mosey conditions, the open windshield is enjoyable. Driving on uneven terrain with the windshield open causes me more concern for the window assembly than hard surface high speed driving.
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Re: Open Windshield Driving

Post by timsresort » Sun Mar 10, 2019 9:58 am

I was once pulled over for windshield down, hot summer day, in CA. Cited for WS "not in place". I stated that it was in place, just in the lowered position. Yeah, no. And our local Jeepers Jamboree goes to great lengths to warn all participants that WS down on the highway is illegal. Since then I only swing the glass up maybe 6 inches and have never had an issue again.
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Re: Open Windshield Driving

Post by Travelfix » Sun Mar 10, 2019 10:26 am

Yup, I used to blast all around town years ago in Mass with the windshield down and always making sure I wore some sort of eye protection. What a blast! I don't know if I'd get pulled over in today's day and age. I guess it depends on the officer on duty.

Driving with the windshield in the down position as per driving with the windshield in the opened position are two different animals. I can see where driving by a police officer with it in the down position would definitely cause concern and get you pulled over where as with the windshield in the opened position wouldn't. ( No more than half way ) I think a warning would be sufficient though!

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Re: Open Windshield Driving

Post by pintelhook11over » Mon Mar 11, 2019 9:52 pm

Here is my .02 cents,

So far I've logged almost 2500 miles on my G506. One of my favorite things about the old War Horse is that they can raise to the Windshield to the horizontal stowed position, Civ'vy trucks can't do that. They only get their little hand cranker to let it out the windshield a few inches... I have wondered about the rules and reg's in California, but I have driven by numerous cops in my neck of the woods and so far the Fuzz hasn't pulled me over. I run with my window up probably 60% of the time, that works out to be about 1500 miles (2414 Km).

My guess is there is a rule for it (heck, Its California!), but I haven't got dinged for it...I'm gonna be a rebel until I get caught.

As for the upper stowed position, I haven't had any issues of catching the incoming wind. I operate the vehicle at 35-40 mph (56-64 KPH) and it has not budged much if any by wind shear. I don't drive with the engine rev'ving on the governor @ 48 Mph (77 KPH) all the time, but I will wind it up that tight every so often. I do have a pair of M-1944 goggles in the glove box for use in window up configuration if necessary. It kinda reminds me of riding a motorcycle with no helmet on!

And a side note is the "Verbal" and engine "RPM" acoustics. If you are talking at an intersection, people around you can hear you talk from quite a distance away. When I drive with all the windows closed It seems like I grind gears more since I don't wind up the engine as much. It sounds louder inside, so it makes my ears think the engine is rev'ving harder than It actually is. I usually run it up to 5-10 mph (8-16 Kph) in 2nd, then up to 20 mph (32 Kph) and then grab 4th and wind it up the rest of the way. I don't usually take off in 1st unless I'm loaded with cargo.



The issue that raises an eyebrow for me is the "dips" at intersections and potholes...

When I hit an intersection with a dip TOO fast it can vertically "Jar/Jolt" the frame assembly. I have been more afraid of a frame failure or a glass fracture in the up position than a "rip off the windshield" effect during movement. I would attribute this lack of wind pressure during operation to having the door windows down most of the time, I like to use the window port as an arm rest. This has gotta helps the incoming pressure have a place to exit I would imagine. I have my little air grabber open a lot of the time too, that is good to cool off my feet.

My floor has no jute or mat to seal up the air either. There is all kinds of places to let out the air pressure at a whopping 40 mph.


My buddy Ron showed me a cool trick one day when we were driving around in his G506 during the hot summer. He said "check this out" the wind shield was open a few inches and he said, "roll your window up". I said, "Why? it's Hot in here." "Just try it" he said. To my surprise the temp cooled off quite a bit in the cab! It just scooped the incoming air and forced the air flow out the floor!

But His floor is like mine, no jute, no mat, all metal with an improvised floor cover around the pedals.
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Re: Open Windshield Driving

Post by Frank USMC » Tue Mar 12, 2019 2:12 am

Was told by a DMV guy with lots of years in DMV, here in North Carolina, if the windshield is designed to open or lay down, it was not against the law to drive it that way.
In South Carolina I drove almost every day with my windshield down back in the 70s.
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Re: Open Windshield Driving

Post by ng19delta » Thu Mar 14, 2019 7:55 am

I used to run my MB windshield down everywhere- and the ONLY time I got grief over it(other than the shot to the forehead by a junebug at around 50MPH) was when I had the cover on it: a friend of mine who was a cop in town told me to keep the cover off, as they can't see it has a windshield... And this I would do in any weather, save rain (when i didn't drive it). When the canvas was up, I'd swing it to just about 90 degrees, and riun it that way, no problems, at any speed.

With the WC, I tilt it forward a bit when driving- it is more "aerodynamic"(as if the WC had a clue what that term means). I'd have no problem running windshield down if I felt like it. They were MADE to operate this way...

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