This package adapts a BMW E46 ZF 6-speed transmission to an NA or NB Miata, with either a Honda K series engine, or the factory Mazda BP engine. It's designed to provide customers with high horsepower turbocharged builds with a very stout transmission option with similar gear ratios to the Miata 6-speed. Because of the similar gearing, this transmission option can also be paired with the a factory Miata 1.8 Torsen differential with our required PPF delete package.

New for 2025: Our new 3.5" aluminum driveshaft features larger diameter splines machined to ultra-tight tolerances, eliminating the slop sometimes found in older steel shafts with smaller splines. This design ensures consistent smooth power delivery, improved durability, and vibration-free operation even at high speeds, having been thoroughly tested to 150+ mph on the racetrack.

All parts included are proudly made in the USA.

Lead times for shipment vary, always reference our Current Lead Times page for up to date timeline for order fulfillment.

This package includes the following parts:

-Engine/transmission adapter plate, for either Mazda BP or K series engine CNC machined steel, zinc plated, with all hardware and dowel pins.

-A specific BP or K to E46 6-speed flywheel (different geometry than the 5-speed). This flywheel (12 lb.) bolts directly to the BP or K crank and accepts a 240mm E46 clutch kit, 22 spline.

-Short shifter, stainless steel, with Miata geometry on top (Miata 10x1.25 thread pitch, height, shape, and throw are identical). The shifter has ZF 6-speed specific BMW geometry on the bottom. Ball bearings replace the OEM BMW plastic components for improved shifter action.

-Custom length selector rod, aluminm, dual sheer design. Our design eliminates the components that often result in a sloppy BMW shifter.

-Custom selector joint (no more worn plastic bushings) and stainless steel shifter pins, with retainer clips.

-6-speed shifter plate, billet aluminum, that bolts to the top of the Miata transmission tunnel and replaces the rubber Miata outer boot. It accepts the BMW shifter ball bushing and our custom short shifter in the center.

-NEW aluminum 3.5" driveshaft. Can be configured to bolt to a GM Getrag diff or a solid-mounted Miata Torsen diff.

-V8R frame rails with transmission crossmember pads, powdercoated gray

-ZF 6-speed transmission crossmember

-ZF 6-speed rear transmission mount bracket

-Energy Suspension GM style poly transmission mount

-3/4" Wilwood clutch master cylinder kit with braided stainless clutch line

-E36 clutch slave cylinder

-BMW reverse light connector with pigtails

Notes:

• An E46 clutch kit must be used with our flywheel, specifically a clutch kit for a 2004-2006 BMW 330i or 330Ci (22 spline, 240mm clutch disc). It must be a kit that includes a pressure plate designed to fit an OEM E46 flywheel. 
• Use Honda flywheel bolt 90011-RDB-000 for K series engine
• Use BP flywheel bolts for stock Miata engines
• Download installation instructions here

KPower Recommended Supporting Parts:

• Miata Differential Mount for PPF Delete (Required for stock Miata differential)
• ACT HD Clutch kit or Spec Stage 1 Clutch kit for street use
• Spec Stage 3+ Clutch kit for high heat/track use
• Haltech GPS Speed Sensor for customers running a Haltech ECU wishing to retain a working speedometer as the Miata speed sensor is lost when removing the stock transmission
• Getrag Differential Upgrade