Installing a new clutch while you swap a tired old engine out of the car is a good idea. It’s one of those “while you’re in there,” things that make a job more comprehensive and it tends to create a better finished product.

For the 2.5 swap in the 2006 TT5 MX-5, we knew it was going to be driven primarily on the street with some track use from time to time. Thinking back to our feature story on how to choose a clutch, we sourced one from Advanced Clutch Technology for a clutch kit and a lighter-than-stock flywheel.

Because the car is going to be a daily driver, we went with a full-circumference disc with organic friction material and a sprung hub. If you don’t know what any of that means, you can check out the video on YouTube, which is a step-by-step tour through the Advanced Clutch Technology factory in Lancaster, Calif., detailing how clutches are made.

The flywheel itself is only marginally lighter than stock to improve street drivability and the pressure plate was the standard ACT model, the only one offered for the 2006 MX-5. That seemed like it would be strong enough to hold the increased torque of the 2.5 liter four.

The kit also came with an alignment tool, a release and pilot bearing and the snazzy purple grease for the splines, the release bearing, and the throw-out fork tips. It had everything needed for the swap.

Before we get into the specifics and the in-depth photos, there are a couple of things to note. First, unlike previous generation Miatas, the pilot bearing is different on one end than it is on the other, so there is a right way and a wrong way to install it. For the NC chassis, you install the bearing with the lip toward the transmission. From the information we found, the lip is to seal the grease in the needle bearings. There is a factory special tool for tapping it into place, but a 14 mm deep socket is a good substitute.

Second, the flywheel and pressure plate bolts get torqued incrementally. In other words, you don’t torque the flywheel bolts to 82 foot-pounds on the first round. You first torque them to 40, then 60 and then the final 82. There’s a similar sequence for the pressure plate bolts, which ACT supplies in the kit.

You’ll also need a tool for locking the flywheel in place, which is something that does not come in the ACT kit. We sourced one from Flying Miata. As with everything, patience and attention to detail are paramount. Here’s how the job unfolded.

Inside the pilot bearing, you can see the greased needle bearings and lip seal on one end. The lip faces the transmission to seal in the grease.
The factory service manual shows a special tool for tapping the pilot bearing into place, but a 14 mm deep socket is a pretty good substitute.
Tap the bearing all the way into the recess in the crankshaft. Notice how the lip inside the bearing will face the transmission.
A little dab of red Loctite is recommended to keep the flywheel bolts in place. If you are reusing the old bolts, it’s a good idea to hit them all with a wire wheel to clean out the old thread locker and accumulated debris.
To keep the flywheel from turning while torquing the bolts, you need a flywheel locking mechanism. This one from Flying Miata was made specifically for the MZR engines.
To torque the flywheel to the crankshaft evenly, increase the torque specs incrementally before tightening the bolts to the final and top spec. We went from 40 to 60 and then to 82 foot-pounds.
When you have the flywheel torqued in place, you are ready to install the clutch disc with the supplied alignment tool.
Before installing disc, clean the friction surfaces on the flywheel and the pressure plate with brake cleaner to remove any dirt or petrochemicals the factory used to prevent rust.
Insert the black plastic alignment tool through the splines on the disc and then place the end of the alignment tool in the pilot bearing. Push it all the way into the pilot bearing and press the disc onto the flywheel.
The ACT kit comes with new Allen-head grade 8 fasteners for the pressure plate. Drop the washers on first so they’re ready to go.
ACT recommends some thread locker on the pressure plate bolts. Final torque is just 19 foot pounds, so thread locker is essential.
Here again, you need to sneak up on the final torque spec so that you get it evenly applied around the full circumference of the pressure plate. First torque the bolts to 10 foot-pounds, then 15 and then 19. Each time you torque the bolts, check the alignment tool to ensure it pushes in and pulls out easily.


When the pressure plate is torqued, you should be able to push in and pull out the alignment tool using just your fingers. If it binds, you need to disassemble, figure out why it binds and then reassemble.

With everything in place, you’re ready to remove the alignment tool and install the transmission.
Reinstalling the transmission on the garage floor is a bit easier than doing it under the car. Plus, it makes installing the engine easier, too. For the 2.5 swap, we installed the engine in the subframe, set it on top of the legs of the hoist and used a transmission jack to maneuver the transmission into place.
Image courtesy of Eric Green

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