Harley-Davidson Fly By Wire Replacement Gear Set

Harley-Davidson Throttle Body Gear Fix – Stop Limp Mode

Overview

Stop the "Limp Mode" cycle. This model is a 1:1 replica of the internal gears found in Harley-Davidson Throttle-by-Wire (TBW) throttle bodies, primarily found on 2008–2011 Models (Street Glide, Road King, Electra Glide, etc.).

The OEM plastic gears are notorious for stripping or breaking teeth, which triggers a "Limp Mode" and usually requires a full throttle body replacement. This model allows you to manufacture your own replacement.

What This Model Is

• A reverse-engineered gear set based on an OEM throttle body
• Designed to replace the internal plastic gears that commonly fail
• Intended for experienced DIY users comfortable working on throttle bodies

I originally printed this model to verify fit and geometry.
For actual use, I CNC-machined the final version from brass and installed it successfully.

Production Recommendations
⚠️ CRITICAL NOTE: This is a high-stress, high-vibration, and high-temperature environment. Standard PLA or PETG will fail and could leave you stranded.

⚠️ I have not yet validated a fully 3D-printed version in real-world riding conditions.

For CNC (Recommended): Use Brass or 6082/7075 Aluminum for a permanent "lifetime" fix.

For 3D Printing: If attempting a printed version, consider:

• PA12 / Nylon
• Carbon-fibre reinforced Nylon
• PEEK / PEKK
• Other high-temperature engineering polymers

PLA, PETG, or standard hobby materials are not recommended.

Actuator Gear: The main gear attached to the butterfly shaft.

Idler/Reduction Gear: The intermediate gear that bridges the motor to the sector.

Disclaimer

This is an aftermarket repair solution. The throttle is a safety-critical component. By downloading and using these files, you acknowledge that you are responsible for the mechanical integrity of your vehicle. Test thoroughly in a controlled environment before hitting the highway.

Installation Notes

• The actuator gear was secured to the shaft using an M4 headless machine screw
• Ensure correct axial positioning
• Check backlash and full throttle range before final assembly
• Confirm smooth operation and no binding
• Clear fault codes and test before road use

This component is part of a safety-critical system.
Only attempt this repair if you are confident in your mechanical ability.

Why This Exists

Throttle body replacement is expensive.
In many cases, only a small internal plastic gear fails.

This model is intended as a cost-effective solution for experienced DIY users and engineers.

This is not an OEM part.