K24 Miata Swap – Transmission Installation with the KMiata Adapter
Transmission installation with the KMiata adapter for a k24 swapped Miata is pretty straightforward. The full swap kit includes the flywheel, transmission adapter plate, and so on. I used a Flyin Miata Level 1 clutch that I already had, but I’ve heard great things about SuperMiata’s clutch.
See All K24 Swap Articles: K24 Miata Swap Main Page
Kit Parts
Kit from KMiata with transmission adapter, plus clutch and flywheel bolts
Here are all of the parts required for transmission installation with the KMiata adapter.
Removing the old pressure plate
Original pressure plate still attached to motor
If your motor is like mine, it will still have the old pressure plate attached, assuming it was from an automatic. Of course, this has to go.
Honda crank tool holds the engine
Breaker bar on the back
An impact may have worked here, but I opted for the safer approach. There’s a Honda crank pulley tool
Old pressure plate removed
The flywheel bolts themselves require a 17mm 12-point socket
Notching the transmission
Make the shape in cardboard
Use the cardboard to transfer it to the transmission
You need to notch the transmission to accommodate the K24 starter. Not pleasant to cut into a Mazdaspeed 6-speed, but here we are. I held the adapter plate up to the motor and made the notch in a piece of cardboard. Then, I used that cardboard to transfer my line over to the transmission. For this, I again held up the adapter plate to the trans to make sure I was locating it correctly.
I stuck a trashbag inside the bellhousing
Seems to have protected it
I put a trashbag around the input shaft and other sensitive stuff before cutting on my bench with the angle grinder
Clean and ready to install
Afterwards, I vacuumed it out and wiped it down with brake cleaner
Attaching the adapter
The heater core pipe needs to be pulled out of the way temporarily
The next step is to attach the adapter to the engine. First, the heater core pipe needs to be out of the way temporarily. The mounting bracket interfered with installing the plate.
Bolts matched to holes
This picture illustrates which bolt goes where. In particular, there are three differently-sized bolts that go in specific locations.
This one bolt goes backwards
The longest bolt goes in backwards, attaching the starter to the plate.
The original bolt with a washer didn’t have enough thread engagement here
Hardware store m12 65mm bolt with 2 washers was the right length
This let me torque this properly
It’s worth noting that my “medium” bolt for the adapter was too short. With the provided washer on the bolt, it couldn’t engage enough threads to properly torque. A 65mm long M12 bolt from the hardware store, combined with two M12 washers, was the correct length. KMiata guessed that the wrong bolt got into my kit.
All torqued down
At this point, I torqued all of these bolts down. I went around in a star pattern, tightening them evenly. I’m not sure it was strictly necessarily, but it doesn’t seem to have hurt.
Install the flywheel
Held on with two bolts for now
The flywheel goes on next. It installs in this orientation, with the teeth meshed to the K24 starter as you’d expect.
Brand new Honda flywheel bolts
I used 8 brand new flywheel bolts, Honda Part Number 90011-RDB-000. KPower will sell a set as part of the kit.
Same two wrench method as removal
Same socket, torquing bolts
I used the same method as before to torque these down. I torqued them in a star pattern, like you’d do with lug nuts. Mazda calls for loctite on these bolts, but Honda does not. I put them in with no thread locker or sealant and haven’t had any leaks.
Trimming heater core pipe bracket
Heater core pipe bracket contacts the adapter
At least on my car, the heater core pipe bracket pictured sticks out just far enough to contact the adapter.
A quick grinding made enough clearance
I pulled it out of the thermostat housing to grind it down. This is literal, by the way – it just pulls out. After this, it sat flush against the block as it was supposed to.
Check the pilot bearing
On my flywheel adapter, the pilot bearing pre-installed in the flywheel was bad. It caught in one place when I turned it by hand. KMiata sent me a replacement, but this is worth checking before you get the motor in the car. If it doesn’t spin freely, it’s a cheap part to replace as well. It’s a 94-01 Acura Integra pilot bearing
Install the clutch
Remove these allen bolts from the flywheel before installing the clutch
Before installing the clutch, remove each of these allen bolts from the flywheel.
Clutch goes on first
Pressure plate next
The clutch and pressure plate go on next. I used the Miata clutch alignment tool
Remove the alignment tool and you’re done
Remove the alignment tool and celebrate your handiwork.
Transmission bolt orientation
The upper three bolts go here
Lower right three bolts
Very bottom bolts, rightmost one was in previous picture as well
Here are where the bolts go for the adapter plate. In particular, the smaller head bolts are used for the bottom 3 holes. The shortest larger-head bolts go in the top two positions.
Install the transmission
The notch looked like this when installed
Your transmission can now go on. It may take some wiggling to get the input shaft to line up properly with the splines in the clutch. Don’t force it. Once it’s on, you can start installing the bolts to mount it to the adapter plate. Also check the notch you made in the transmission to ensure the starter clears properly.
Done
Ready to go in the car
And with that, the job of “transmission installation with the KMiata adapter” is complete. This assembly is ready to drop in the car. Refer to the K24 Miata Swap Main Page for the next steps.