The ZF 8HP automatic gearbox has become the benchmark for modern performance and reliability. Known for its lightning-fast gear changes, impressive torque capacity, and smooth operation, it’s a favorite not only for manufacturers like BMW, Chrysler, and Jaguar but also for enthusiasts undertaking swaps and high-power builds.

Traditionally, taking control of this transmission outside its native platform has been a challenge. Many aftermarket solutions rely on hardware modifications, firmware hacks, or invasive reprogramming that can compromise reliability.

That’s where RM-Primis changes the game.

Why the ZF 8HP Stands Out

Developed by ZF Friedrichshafen AG, the 8HP family packs a compact design with a fully integrated mechatronics unit. Inside the housing lives the TCU (Transmission Control Unit), the “brain” that manages solenoids, pressure control, sensors, and shift logic.

The transmission comes in several variants, each tailored for different torque demands:

• ZF 8HP45 (Gen 1) – Rated for ~450 Nm, common in BMW 3-Series (F30), 5-Series (F10), and Chrysler sedans.

• ZF 8HP50 (Gen 2) – Successor to the 45, more efficient while supporting similar torque, found in newer BMW F/G-Series.

• ZF 8HP70 (Gen 1) – Handles ~700 Nm, popular in larger SUVs and trucks like the Dodge Ram 1500 and BMW X5.

• ZF 8HP75 / 8HP90 (Gen 2/3) – Heavy-duty versions for high-end sports cars and performance SUVs, capable of over 900 Nm.

Drivers praise these gearboxes for their adaptive learning, durability, and balance between performance and comfort. Yet until recently, using them in custom applications meant dealing with invasive modifications.

RM-Primis: Seamless OEM-Style Control

RM Racing Electronics developed the RM-Primis ECU to give builders and tuners true plug-and-play control of ZF 8HP transmissions.

Unlike third-party controllers, RM-Primis communicates directly with the original TCU via CAN-bus. It mimics factory ECU signals so the transmission behaves as if still paired with its OEM engine.

That means:

• Factory-smooth shifts

• Retained safety logic and diagnostic functions

• No case opening or soldering

• No risky firmware “tricks”

With RM-Primis, you keep the OEM reliability while gaining flexibility for custom projects.

How It Works

The system links to the TCU through CAN-bus lines, sending and receiving the same style of messages the stock ECU would. This allows:

• Precise control of shift points and torque requests

• Real-time monitoring of temperatures, pressures, and status

• Reading and clearing diagnostic trouble codes (DTCs)

• Checking firmware versions and logs

Thanks to integration with RM-Tuner software, users can also unlock TCU firmware at no cost, flash updated logic, and even gain access to tuning maps for performance customization.

Benefits of the RM-Primis Approach

• Non-Invasive Setup – No opening the transmission or altering the TCU hardware.

• OEM Diagnostics Intact – Keep factory-level troubleshooting and error handling.

• Plug-and-Play for BMW F-Series – Works right out of the box, no coding tools needed or expensive flashing tools for most setups.

• Free Flashing for Non-BMW Units – Chrysler, Dodge, Jaguar, and others can be converted to BMW logic by simply shipping the TCU module for reprogramming.

• Cost-Effective & Reliable – Avoid expensive standalone controllers and reduce failure points.

• Custom Tuning Ready – Adaptive shifting and map editing available for tailored performance.

Compatibility and Applications

RM-Primis supports a wide range of platforms:

• Direct Plug-and-Play – BMW F-Series (F30, F32, F10) with 8HP45/70 units.

• Minor Adjustments – BMW G-Series with 8HP50/75.

• Flashing Required – BMW E-Series, Chrysler/Dodge/Jeep, Jaguar/Land Rover, Maserati, Alfa Romeo, and more.

If you’re unsure which category your project falls into, our team provides guidance based on TCU part numbers.

Shifter and Harness Options

To complete the integration, RM-Primis also supports BMW F-Series electronic shifters, giving a factory-style driving feel, we also have the original 8 and 10 pin connectors available HERE

RM Racing Electronics offers dedicated wiring harnesses designed to minimise installation effort. These ensure proper CAN-bus communication, power delivery, and clean connections without soldering or guesswork.

Other shifters can be added upon request.

Final Thoughts

Controlling a ZF 8HP transmission no longer requires invasive modifications or expensive standalone controllers.

With RM-Primis, you gain true OEM-like integration, full diagnostics, and adaptive shifting—while keeping the reliability and smoothness that makes the 8HP so desirable. Whether it’s for a BMW swap, a Chrysler restomod, or a high-power custom build, RM-Primis delivers a clean, future-proof solution.