May 12, 2021

Cars that are built to race.

NC MX5 With a BMW Dual Clutch Transmission

4 min read

When our customer approached us with the idea of creating a purpose built MX5 for the WRL endurance racing series we were more than ready to take on the challenge. After a few discussions on what direction we wanted to go with the build the basic idea was down on paper we started searching for a good chassis to begin with.

When the chassis arrived the team got to work on stripping out all of the interior, sound deadening, and paint in preparation of the roll cage being installed. Our fabricator then began installation of the Spec MX5 roll cage kit from MiataCage.com. 

Once the cage was installed and fitted with the hardtop on, the body of the car was masked off so the roll cage could be painted.

The class we wanted to enter the car in allows for certain body modifications to be added to increase the aerodynamics of the car. So while waiting for the roll cage kit to arrive our fabricator began work on the side floors and rear diffuser. We made the side floors almost reach the outer edge of the tires to assure they would be as far into the airstream as possible. 

The aero on the vehicle needs to be strong enough to withstand a significant amount of downforce at speed, so the diffuser is reinforced against the frame of the vehicle to ensure it will hold, as shown by our fabricator.

At this point the hood was cut and the Singular Motorsport hood vents were installed to ensure that air would be evacuated from the engine bay after flowing through the radiator.

While the engine was still out of the car our custom front chassis brace was made and installed. 

From there we began work on the front air dam, and splitter. The air dam was measured out and cut from ABS plastic and mated to a Racebred front splitter.

Once the cage was painted we were able to begin fitting the fuel cell in the rear shelf area behind the seats. With the freedom of getting rid of the stock fuel tank we decided to place the cell in the location we did so that a dry break fuel fill could be added through the rear window on the hardtop. 

Also with the ability to remove the fuel tank we were able to utilize the extra space for the transmission and differential coolers. The coolers are mounted  under the trunk area with hoses running from a naca duct in the passenger side window and a hole cut through the trunk to allow airflow to pass through. The trunk also holds the pump for the differential cooler and the bottle for the Safecraft fire system running throughout the car. 

Beginning on the interior of the vehicle we started with the installation of the Mazda Motorsport steering wheel and the initial wiring of the AiM data system. For the data system we are using an AiM MXL2 digital dash, AiM Smartycam, and the corresponding sensors to feed all of the information to the dash.

After deciding on a good driver seating position a Racetech seat was installed.

For the drivetrain of the car we installed a 2.5l MZR engine with stage 4 camshafts and valve springs from Xero-Limit. The engine is still utilizing a factory computer but will soon be converted to a Haltech standalone engine management system. With the engine in the car a Goodwin Racing triple pass radiator was installed to keep temperatures at a reasonable level.

At this point in the build we were brainstorming with the customer on how we could make the car easy for almost anyone to be able to get in and drive it considering the car is built for endurance racing and will have many different drivers in and out on any given weekend. The decision was made to attempt something that had never been done before, installing a dual clutch transmission and paddle shifters into an MX5.

After an extensive amount of research we decided on a BMW M4 dual clutch with an aftermarket controller to manage it and work began on mating the transmission to the engine.

After an extensive amount of test fitting and measuring, our fabricator was able to create and adapter plate to match the MZR engine to the BMW transmission and a separate adapter to attach Mazda flywheel to the transmission. 

Using this aftermarket controller requires the transmission to be opened up and be re-wired. 

With the engine and transmission mounted the in car the team shifted focus back to finishing out the aerodynamics. Work began fitting the rest of the flat bottom panels under the car, mating the front splitter, side floors, and rear diffuser to make one complete flat surface which is ideal for aerodynamics.

The car utilizes the Spec MX5 Penske shocks, stronger RX8 hubs, control arms, and differential. It is also using the larger RX8 brake calipers and rotors. 

While the cage work was being done our fabricator also started the installation of the chassis mounted 9 Lives Racing wing on the rear of the car.

 At this point we have been extensively testing the car and has been to its first race outing at Circuit of the Americas. The car has proven to be very fast and was leading the GP2 class until a mechanical issues caused the car to retire from the race. But is already back and ready for the 2021 season!

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