I have a gen 1 w126 and I've always wanted a flip key like the ones on the w124 and w140 for this car. Kind of a silly desire but it has always been in the back of my mind as I saw people flipping out the keys on their German and then later other makes as the keys had their time. Now everything is keyless and the flip key is kind of obsolete.

I was nosing around on ebay and I noticed there are these flip key cases for 1990s Mercedes using an HU39 blank blade. I believe these will fit my gen 1 W126. The idea is you take apart your tattered flip key and transplant the electronics into one of these cases and have a new keyblade cut.

I couldn't resist trying one out. They're $8 including shipping each. Even if it doesn't work it was worth a try. I bought two.



Tearing it apart. The old tech was optical I guess. It sends a beam through this red lens? Kind of like the old Jeep Cherokee I guess. The mechanism is deceptively simple. Just two parts, a button and a spring.



So my idea was I could transplant my electronics from my generic car door opener transmitter to this flip key device and cut the key to match my ignition key. I figured it would be pretty cool.

My old key, my old keyless door transmitter and the board inside it. I'm a fool for taking this apart. It has worked reliably for years and will continue to do so if I don't mess with it. The hardest part of converting my SD was jerry rigging the actuator motor into the driver's side door at the master switch. Plenty of threads about how to retrofit here. The retrofit kits are super cheap. I paid something like $12 for mine including linear actuators. This was a big deal when I was pushing little kids around in strollers. I was highly motivated to make my diesels keyless entry.



Unfortunately the board is too big. No amount of cutting with a Dremel will make this work. The key needs room to swing around inside the housing and there just isn't enough room for both the key and the board. Also the old MB design has one button for opening and closing the door. I'd have to wire up some circuitry to remember the state of the locks to use one button since my setup uses two - one for unlock and another for lock.




So off to plan B. Reverse engineer the black plastic box and drop the flip key blank and old board into a new custom designed 3D printed enclosure. Here is my first cut. Nothing fit. There are tight tolerances in there and I didn't understand the subtleties of how it worked. I kind of copied it and designed my version of the box and when I put it together it was wonky. It jammed, it interfered with the key and the enclosure wouldn't quite close.



I printed out 8 versions with slightly different dimensions inside. I'd print, file and sand, measure, correct in CAD, then reprint and try. One by one I got rid of all the mechanical issues. The mechanism is simple but everything has to be fitted just right or it won't flip open properly or close tightly.

Many attempts later. Like 8. A week. A lot of measuring and diagnosing. I almost gave up. Luckily each print costs $0.35 each and takes an hour to print. So I'd do one prototype a day and make corrections then reprint. I ran out of black filament and had to use white for the prototype 8.





Success! Flips great. Holds the old electronics. The entire combo is much lighter than my original setup probably because there is less metal and the plastic 3D print is mostly hollow.



comparison to the original. I had to make it a tad longer but I was able to compensate by making the key loop more compact using a piece of stainless steel safety wire.



I know this is mindless and useless but it was a lot of fun. Somebody forgot to tell me the pandemic is over. I'm still hunkered down in my workshop building stuff in solitary. Hope to show off my keys at the next socal GTG.

I'll have to load up my machine with some black filament and make one in the proper color. If anyone is interested I'll put the models up for free download on Thingiverse. But they are specific to the circuit board in my generic remotes I bought off ebay a long time ago. It seems these $12 keyless entry systems have gone to a different style of remote that runs on 3V coin cells instead of 12V cells.

Although these keys don't come with 123 blanks I bet you can cut down an Ilco blank and file the end so it fits in the flipper mechanism.

__________________
79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles

After many trials, Success! Here is the final version printed in black. I got my keys duplicated. Ouch. $30 each copy but I figure it is a special machine and my lock man has rent to pay. It actually took him 10 times as long as a cheap house key because he milled the slots slowly. The key fits. He did a great job.

Here is the final installment of images.

$16 for flip keys + $60 duplication of blanks + $4 filament = $80 total. ouch. so much for a cheap project. well, at least I have extra keys!



tons of frustration. I had to learn what every little notch and flange did inside the key mechanism.



It has a key loop but it really doesn't need one. The whole idea was to make the whole thing one piece.





This thing is lighter than my original remote and key combo. There's that old wives tale about putting too many keys on a ring wearing out the lock. Might be true.

__________________
79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles

This is too cool…

Impressive prototyping!

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1981 240D 4sp manual. Ivory White.

Hey Shern,

Thanks. Definitely stretched my skills beyond what I'm comfortable with.

I tested the key on a drive today. It felt a little clumsy. The original key is smaller and more natural to turn. This thing feels like I have a zippo lighter connected to my key when I rotate it. It feels more like a screwdriver than a key when I start the car. Just an observation. It'll take some getting used to.

I don't know how people deal with some of the huge flip keys on makes like BMW in the early 2000s. Some are like a box of Altoids bolted to the key.

Like everything not quite what I expected under real world testing.

I often accidentally pressed the lock and unlock buttons while turning the key. So I made a little guard that looks like two doughnuts that glues on around the buttons to create a recess.

__________________
79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles

Well I’ll be a monkey’s uncle. I never bothered to search w126 flip key on eBay. On the pricey side but they have gone through the trouble to make it look like the w140 remotes. Even the red light works though the unit is obviously radio frequency.

A note on this design. The key is turned 90 degrees. That is where I fumble with it. The angle of the handle when you turn the key is just wrong ergonomically because we’ve rotated the key head 90 degrees from the MB designed position. I finally put my finger on it so to speak - why it feels awkward.

https://www.ebay.com/itm/154364718687?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=z41QlRVeTwG&sssrc=2349624&ssuid=40yPko-dQXe&var=&widget_ver=artemis&media=COPY

Oh no I’m an idiot!

https://www.ebay.com/itm/144159292715?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=q0gfO6h2Tou&sssrc=2047675&ssuid=&widget_ver=artemis&media=COPY

__________________
79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles

Very nice

Nice work. A labor of love and learning to use your tools.

I just need to retrofit keyless to my w124 and w126 cars. I’ll be happy with basics.

Curious who your key guy is since making duplicates of MB laser keys is a pain.

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Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (113k)
1991 350SD (206k)
1991 300D (228k)
1993 300SD (291k)
1993 300D 2.5T (338k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (265k)

Past Diesels:
1983 300D (228K)
1985 300D (233K)

Kwikeys. Lake Forest, CA.

It’s this little kiosk like an old Fotomat. The owner is an older gentleman from the Middle East. He proudly wears his MB Key on his belt and drives a W210. He has all the old MB blanks. He always comes out to check our diesels and says “take care of that and it will last a long time.”

The key was cut on a little machine that looked like a tiny milling machine crossed with a pantograph. More shops are picking these up because I believe they are getting popular in economy cars like Honda and VW. My wife’s 2012 Accord and our 2008 Civic have keys made on a similar machine. Perhaps the radius of the cutter isn’t a standard on the old MB stuff.

I’d keep asking around.

__________________
79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles

Wow C ;

I find this fascinating .

I too love sweating the details on my various vehicles .

I'm particularly impressed with your perseverance .

$80 to get what you want isn't much unless you're broke, a few of us lucky ones can play like this .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Hey Nate,

$80 doesn’t even fill my tank.

I guess I could have gone to see 8 movie matinees. That would have entertained me for 12 hours. That would have cost $80 too.

I try to think about things in these terms when I realize I’ve just spent my hard earned cash on something mindless that kept me happy for many hours.

The flip keys will be fun when they confuse the hell out of people who didn’t think they existed in 1982. My usual remark to this is “It’s and S-Class Mercedes.”

__________________
79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles

Agreed .

We're the lucky ones who can afford to do this ~ I wasn't always able to drop $ into a project as I had a family to feed and house .

Many here don't know about this facet of most American's lives, that's a pity .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better