for those of you who acquired a spare trunk for the track, some might have also came with a key tumbler as well but not the key that goes with it. as you might already know, if the electronic solenoid that opens the trunk latch ever fails (this happened to me twice on my integra), and you have a full interior, you are pretty much Sh*t out of luck in trying to get back in because it's going to be a nightmare to get to the OPEN lever from the cabin. This is what I did to mine so that my master and valet key works with the tumbler that came with my trunk. (i have called honda and they do not repin a cylinder to match your key, they will however sell you a new cylinder with a matching key for 45 dollars. my goal was to have 1 key, not 2.)

this is what your tumbler looks like after you remove it. the orientation of the thing is right side up right now with the metal rod going across it from the bottom remember this orientation when you reassemble. get a plier and wedge off the lock ring holding the plastic thing in.


once the ring and plastic is off. you will see a spring. remember this orientation as well. there are 2 hooks , one is lower than the other. you need to remember which side is which.



after you remove the spring, remove the outer portion of the tumbler by prying the shiny metal piece off. be careful and work your way around it little by little so you don't damage it. it is held in by 2 dimples on opposite sides.


(forgot to take a pic of this part). now, put your master key in the tumbler and see if you can turn the tumbler by wiggling it and pushing on the pins to get them all to seat flush at the same time. this is a little bit tricky. if you can get it to turn, you can slide the entire thing out. if not, you have to push on each individual pin while applying a little force to turn it until you can get it to turn. the goal is to remove the cylinder from the housing. don't worry if the pins start to fall out. after all, this is a spare tumbler that wasn't meant for your master key anyways so no harm done. after you remove it, it should look something like this. (this is actually a pic after I repinned and grinded at some of the pins. you will understand after reading the below)


now align all the pins and stick your master key in. you will notice that all the pins will now sink into the cylinder. however, some pins more than others. make a mental note of which pins still stick out. then put in your valet key instead and see which pin is behaving differently. here is an image of mine with the valet key in. notice that the last pin sticks out which prevents the cylinder from turning. i left this pin alone because i need it to prevent it from turning with a valet key.


(forgot pics here). next step, you will have to swap the pins around until most or all of your pins are pretty flush. BE CAREFUL NOT to lose any of the pins or the springs. they are small and hard to find. you will need to place your finger gently over them when you remove your key or else it will shoot out and lose it. because I did not have a stash of spare pins lying around, I had to modify some pins to make them work. first i put the master key inside, and i only swap the pins that are sticking out. i swapped 1 pin that is sticking out too much for a pin that was sunken in too much and see if that helps. this is still guess work because the key has different cuts along it's length. but luckily, i was able to get them pretty close. once i was done with the pinning, I left the key in, slide it back into the housing and see if it would work. NOPE, it didn't. I took it back out with the key still inside. I took a dremel and took off all the high spots. reinsert and see if it works now. below is an image of where I grinded away. keep in mind the adjustments are very minute, no more than 1mm.
circled are areas I grinded away.

here is an image of the grinded pin still engaging the anti-rotation groove when the key is out. this is why you grind as little as needed.


below is a pic of what it looks like after everything is done with the key out.


place the cylinder back into the housing and make sure it spins with the key in. then reinstall the spring with the 2 hooks in the correct position. I placed the hooks in the grooves first then I used a screwdriver to slide the coils over the rest of it.


replace the plastic and spring washer along with the outer shiny metallic piece on the opposite side and you are done! put it back on your trunk and test it to see if it works.

 

I have a jdm ap1 early. Keys were worn.
Took to a local lock key outfit.
Guy removed the trunk lock from which he obtained the factory key code. Like a serial number.

From that he made keys matching the factory based on the code.

He did not use my worn keys.

It worked like a charm for about 40usd.