I recently read a comment from someone who said losing this door is an "RV right of passage". What baloney! Don't lose it and this is how to prevent that - and for less than four dollars.
Now, I cannot take credit for this idea. I read about this idea in a magazine on motorhomes, but I have modified the idea. Here we go.
First it is important to understand - if you don't have an RV yet - how this door "locks" in place. At top of the door in the center there is a vertical slot. From behind that slot a plastic ring on a flexible strap comes through the slot and then is turned horizontally and then pushed down so that it lies flat against the door. IF this remains this way the door will not come off. Why would it not lie flat? If the strap starts to lose its elasticity, if someone maliciously comes along and turns the ring vertically, or if vibrations cause the ring to lift and turn - all reasons why the door may fall off - and I am sure there are many others.
The simplest solution would be to put a hasp lock through the ring and lock it but then you will have "BANG, BANG" as you drive down the road with the lock hitting the side of the door with every bump. Not really a good idea.
What the magazine suggested was to take a screw and nut and put it through the ring, preventing the ring from coming through the slot without removing the nut and screw. Nice idea, but I could see the screw also bouncing around if it was loose in the ring and also scratching the paint on the door. So I modified this idea for my Roadtrek by using a nylon screw and nut. You need to buy two things - both found in Lowes - not on the wall with screws and nuts but in the specialty parts drawers in the same aisle of the store.
You can see the parts number, sizes and descriptions on the packages above. You want a 1/4-20 X 1/2 nylon screw. With that you want matching 1/4-20 nylon nuts. You get two screws in a package and 4 nuts in a package. Each package costs less than $2.00. Total cost for the whole project is less than $4.00. The 1/4 is the thickness of the screw. The 20 is the thread on the screw. The 1/2 is the length of the screw.
I tried a longer screw and I also tried a matching wing nut to the screw shown above. The longer than 1/2 inch screw was too long and the ring would not sit against the door when it was in place. The wing nut was much too big - none smaller were to be had - and that prevented the ring from sitting flat against the door. With anything through the ring, the ring will not sit exactly flat but with the right combination shown here, you can get the ring as flat as possible with little chance that it will stick out too far from the side of the van and become a problem.
To remove this to open the door, just unscrew the nut and remove the screw. If the nut seems tight, use a coin in the slot of the screw to turn the screw to open it as you hold the nut with your fingers. It should be no effort to unscrew the nut - but after some time after putting it on, it does seem to tighten more on the screw - though not on the ring.
Yes, there is still the possibility of someone stealing the door. If they really want it there is not much you can do to stop that as the ring could just be broken even with a lock through it. But with this, you will cut down the possibility of losing this door by - how much? 90%? More? Better than nothing is always good! And the nylon will not scratch the paint.