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

The stuff

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

Motor

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

Honda crank tool holds the engine

Breaker bar

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 that slots right in and holds the crank pulley steady. If you’re removing the crank pulley, you can attach another wrench and break the crank bolt free without spinning the engine. In this case, I use the crank pulley tool to hold the crank while I break the flywheel bolts free. Same idea.

Removed

Old pressure plate removed

The flywheel bolts themselves require a 17mm 12-point socket.

Notching the transmission

Cardboard Shape

Make the shape in cardboard

Transfer

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.

Trashbag

I stuck a trashbag inside the bellhousing

Protected

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.

Ready

Clean and ready to install

Afterwards, I vacuumed it out and wiped it down with brake cleaner
to make sure I didn’t have any shavings remaining. After that, I greased the usual surfaces and throwout bearing. Maybe overly-paranoid, but the transmission survived.

Attaching the adapter

Pull out of the way

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

Bolts matched to holes

This picture illustrates which bolt goes where. In particular, there are three differently-sized bolts that go in specific locations.

Backwards

This one bolt goes backwards

The longest bolt goes in backwards, attaching the starter to the plate.

Not Enough Threads

The original bolt with a washer didn’t have enough thread engagement here

Hardware Store

Hardware store m12 65mm bolt with 2 washers was the right length

Proper Torque

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.

Torqued

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

Two Bolts

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.

Honda Bolts

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 Method

Same two wrench method as removal

Same Socket

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

Contact

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.

Ground Down

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 with many aftermarket replacements.

Install the clutch

Remove These

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

Clutch goes on first

Pressure Plate

Pressure plate next

The clutch and pressure plate go on next. I used the Miata clutch alignment tool that came with my clutch. They’re handy to keep around. The parts go in the orientation pictured. Don’t get these backwards or your clutch won’t work. Re-install the allen bolts once the pressure plate is on and torque evenly.

Done

Remove the alignment tool and you’re done

Remove the alignment tool and celebrate your handiwork.

Transmission bolt orientation

Upper Three Bolts

The upper three bolts go here

Lower Right Three

Lower right three bolts

Bottom 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

Final Notch

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

All 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.

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