Hangar works #12 – Bonnet locks

As explained in the previous post (Hangar works #11 – Boot lock), we were genuinely concerned that neither the boot nor the hood of the Morgan 3-Wheeler had a lock.

Now it was time to solve the bonnet safety. And I have to say that, again, I’m very satisfied of how I’ve solved it!

After analyzing the bonnet structure in detail, how it sits on the main body, I had a clear idea of where and how secure the bonnet against the stealing baboons.

As it happened with the boot lock, the solution I came for does not intend to be the safest and the strongest, but a preventive locking system to protect against thefts by opportunists.

So, let’s go with the description and explanations!

The bonnet of the 3-Wheeler has its Dzus fasteners along its bottom line, two on each side. Looking in detail where these Dzus fasteners are fixed, so where their lock springs are situated, we can see that the closest one is situated in a large plated area just in front and below the rearview mirror.

The best area is in front and below the reaview mirrors.

The bonnet overlaps generously over this area, so it looks like the best zone to find a solution. But what’s beneath this area? Having a look from the inside, we can see the back support and lock spring for the Dzus fastener, and that a relatively large area of this body plate is free. It’s bordered by a couple of chassis’ steel tubes, and the ash wood arch behind the dashboard. The major concern can be the wires fixed to the vertical steel tube. I’ll have to be careful not to damage those while drilling.

The area – pilot side – looking from the inside.
Same picture with some description.

Now that we know we have a nice area where the bonnet overlaps the main body, and that allows us to work on, what’s the idea?

I normally focus my solution’s research in the automotive industry. And when nothing shows up there, I investigate the nautical world where you can find a huge amount of wise solutions to specific needs, and with high quality materials. And this was the case here! With inventiveness and a little bit of imagination, I came up with the simplest possible solution, using a hatch cover pull.

A nice nautical accessorize

The hatch cover pull I chose is made of 304 stainless steel, and its dimensions are shown in this drawing below.

Combined with a spring, some washers, and a luggage key lock, this is the solution I got.

The items shown in the drawing above are:

1 – Luggage key lock or lock pin. As we’re looking for protection against thieves, I’ll use the luggage key lock instead of the lock pin. It has to be a standard one, with 3,2 mm thin shackle so it can get through the modified drill of the hatch cover lock. The key locks are a pair, so both sides pilot and co-pilot key locks open with the same key. Combination locks are not recommended at all for this application, as you can’t see them underneath the dashboard! So, getting the right number combination can be a really funny task.

2 – A stainless-steel washer, with 7 mm diameter hole – then sold as for 6 mm screws -, and especially large outer diameter of 18 mm to increase the area for the spring contact. I have drilled a 1,5 mm hole into the washer, to pass through the nylon cord.

3 – Stainless steel compression spring. This is a 10 mm outer diameter compression spring, 9,9 mm inner diameter, with 3 kg strength, and 70 mm long. I have cut the spring to 45 mm length, to get the best compromise between strength and easiness to compress and putting the lock.

4 – Nylon cord. Very thin one. About 1mm diameter but very resistant. Why this cord? Easy to understand: if the washers and the spring are all loose pieces, you can drop any of them to the 3-Wheeler floor, in the footwell. This can happen very easy if you consider you’ll be trying to slide the shackle of a small lock through a very narrow drill in the hatch cover pull’s stem, in a place you don’t see, so “at touch”, and while maintaining the whole with a compressed spring. It’s not easy to do and having everything flying off will happen for sure. Then, looking inside the deep, dark and narrow footwell of the Morgan 3-Wheeler for a washer or a spring, can be really difficult, if not ridiculous, unless you’re a hyper-flexible acrobat of Le Cirque Du Soleil. The nylon cord keeps the washers and the spring all together as a “unit”, much easier to handle with, and avoids the flying off of any part. The cord passes through the 1,5 mm drill of the washers (including the plush no#6 glued to the washer no#5) and then a simple overhand knot keeps it secured to each washer.

5 – Another stainless-steel washer, with 7 mm diameter hole – then sold as for 6 mm screws -, and especially large outer diameter of 18 mm to increase the area for the spring contact. I have drilled a 1,5 mm hole into the washer, to pass through the nylon cord. So identical to no#2.

6 – Plush sticker. Normally put under the feet of furniture to avoid scratching the floor when moving the furniture. Cut and drilled to the no#5 washer size and holes. This plush will be in contact with the internal aluminum wall of the cockpit and avoids the metal-to-metal contact eliminating scratches on the paint and possible metallic clinks.

7 – This is a tailor-made decal. I made it with my home printer, using adhesive paper, and covered it with a transparent adhesive film. So, I can choose any shape, words, and colors. It will be glued around the hole of the bonnet where the stem of the hatch cover pull enters, so visible from the outside when this last one is not in place. This decal is multipurpose. First, it protects the bonnet paint around the hole from scratches and friction marks. Second, it reminds you to put the locking system. And finally, it’s pure decorative. I have printed many, so when the first ones I glued on the bonnet will wear out, I can replace them right away and even change the design and color if I want to print new different ones. When in place, the head of the hatch cover pull hides completely this decal.

8 – This is the hatch cover pull. It must be slightly modified as follows: its standard hole for the ring pin is only 3 mm in diameter. Using a very high-quality bit – remember we’re working on high quality and hard 304SS – and using a powerful drill at its lowest possible RPMs, I increased the diameter to 3,5 mm so the 3,2 mm shackle of the lock fits in. It’s very important to have everything properly secured and positioned before drilling, as the stem of the hatch cover pull is just 6,2 mm, so there is very little room for error! If the bit deviates from the axle while drilling, you can destroy the stem making it totally useless for its purpose.

9 – Sticker decal 3D resin domed. With an outer diameter of 30 mm matching the 32 mm flat heat of the hatch cover pull perfectly! It’s a high-quality decal, outdoor resistant to sun (UV), heat, washing, rain, etc. Purely decorative. I could have left the hatch cover pull as it is, with a flat polished stainless-steel head. But I find it bland, so putting this high-quality sticker on it with the Spanish Air Force cockade is much more decorative. On the co-pilot side I put the Guatemalan Air Force cockade, in honor to AM, the best possible co-pilot! The source of these decals is a local company in Madrid, and they can do almost any design you want! Choose yours!

Once everything is placed, the locking system is reduced to three pieces. The truth is that they’re five, but I say three because the washers and the spring are tied together with the nylon cord.

And finally closed, the scheme is very simple.

The following video, with a terrible Spanish accent (sorry for that) explains the philosophy of the locking system and shows how it works.

After building on the locking system, now it’s time to install it on the Morgan 3-Wheeler!

I took detailed measures before deciding where exactly I should drill the holes.

Since the beginning I know and accept I won’t have a direct view on the locking system inside the cockpit while placing the key lock. With this negative part in mind, I chose a place to drill in the reduced available area, more based in aesthetics and being sure I won’t damage anything while drilling.

First thing was to remove the bonnet.

NOTE: If you plan to do this in your M3W, you may choose other position for the holes. However, you should take into consideration the following comments. If you drill higher, then the bonnet shape is curvier so the flat head of the cover hatch pull may not seat completely flat. And the access to the system in higher position makes it more difficult while closing the system with the washers, spring, and key lock. And if you drill lower, you’ll be too close to the Dzus fastener. You may gain a little bit of “comfort” while closing the system from the inside, but still won’t be much better. At last, it’s your choice, and you may differ from mine!

Then I marked the dot with a simple chalk marker.

The spot to drill marked with chalk.

Obviously, I marked the exact same spot on both sides. The location chosen is 70 mm up the Dzus hole, on the line parallel to the crease of the body plate where the edge of the bonnet will fit. This line runs 90 mm from the crease of the body plate.

Exact measures shown in this picture.

After marking the place to drill, the drilling process was as follows. Always using a high-quality bit (in my case I used Titanium ones made by Black & Decker) and setting the drill at its lowest possible RPMs. This process is done on both sides, of course…

  1. The black synthetic protection of the area is thick enough to assure that your drill will work on the right marked spot. So, we do the first drill from the outside with a small bit of only 2 mm size.
  2. Clean carefully any aluminum burrs left on the inside of the hole.
  3. Put the bonnet back on and fix it with the Dzus fasteners making sure it’s in normal position.
  4. Now from the inside of the cockpit, place the bit through the drilled hole. Once you passed the bit thought the hole, make sure you position the drill totally perpendicular to the bonnet plate. Then drill very slow and careful with very little pressure, until the bit comes out the bonnet.
  5. Change the bit to 3,5 mm size. And, always from the inside and very carefully, drill over the 2 mm hole to make it 3,5 mm with the new bit.
  6. Change again the bit to 5 mm size. And, always from the inside and very carefully, drill over the 3,5 mm hole to make it 5 mm with the new bit.
  7. Last change of bit to 6 mm. And, always from the inside and very carefully, drill over the 5 mm hole to make it 6 mm with the new bit.
  8. Finally, with a lot of kindness, play with the drill and the 6mm bit to increase very little the holes’ diameters, so the 6,2 mm stem of the hatch cover pull passes through both of them tight but without too much friction.

Note that finding the hole from the inside of the cockpit won’t be easy, as the hole done is originally very small (just 2 mm), and you don’t have direct view of the area. Be careful not to scratch the inside paint with the bit looking for the hole!

During the whole process, after each drill clean carefully blowing the aluminum burrs away. Careful if you do it with a cloth or your hand! The aluminum burrs can scratch the paint!

Now all holes are done!

From the outside, it’s just a 6,2 mm diameter hole.

To finish the job I stick the home-made decals outside the hole of the bonnet.

The decal protects the paint from scratches and friction marks.

The stem of the hatch cover pull shall enter tight but without too much friction.

The hole shall be large enough to insert the stem tight but without too much friction.
Inserting the pilot side hatch cover pull.
Co-pilot side.

The most difficult part now is placing all the internals, so the washers and spring and slide the lock shackle into the stem’s hole.

View from the inside.

With the hatch cover pull in place, the first washer with the plush is easy to enter. And the spring after is easy too.

With the first washer (with plush) inserted. The nylon cord keeps all together.

But then compressing the spring and enter the end washer, and maintain it all compressed while you slide the lock’s shackle, just by touch, because you can not see anything in the area unless you are a spectacular contortionist, it is the most difficult. Although with a little practice you end up getting the hang of it.

Putting the key lock is not easy. But once done, it’s secured and neat. No friction noises nor metallic clinks.

Finally with the whole in place, you’re not supposed to remove the bonnet frequently, so in my honest opinion this locking system is worthy and a very simple and elegant solution.

Pilot side with the Spanish Air Force cockade
Co-pilot side with the Guatemalan Air Force cockade

From the outside, you don’t realize this is a lock system. And the force of the spring is strong enough to avoid pulling it out unless you have steel claws instead of nails.

And unless you know it’s there, you can’t notice that you have a key lock on each side of the cockpit just below the dashboard. In fact it’s invisible unless you dive into the footwell heads first.

Enjoy these result pictures!

Larger pilot side View.
Larger co-pilot side View.
With some distance, the heads of the lock system with the cockades look nice.

I hope you liked this solution and enjoyed this post!

3 Replies to “Hangar works #12 – Bonnet locks”

  1. Top instructions again, thanks for sharing . I don’t plan on doing this to my M3W but if I did it is the way to go.

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