G25, G27, G29, G920 Potentiometer Replacement

This is my version of the gears for replacing the potentiometers of the Logitech G29 (should be the same for G25, G29 and G920 but I can't guarantee it, comment if it works for you!), with generic dirty cheap Aliexpress ones (WH148) as the originals cannot be easily found.

You also need a M4 countersunk head screw for this mod, as self centering locking mechanism, instead of the original screw. (Not like is shown in the photo as there was a version that used the original screw, but it proved unreliable.)

My friend tested this mod for more than a year and it is still working fine.

Print Settings

I have printed it with a Bambulab A1 in PLA material, at 0.2mm layer height, 3 walls, no supports.

Notes:

• Both the printer and the filament should be decently calibrated.

• I have used PLA but PETG is probably even better.

• The small gear is more critical to get it good because of its size, in particular you need good retraction, I recommend to print with the Arachne wall generator and random seams in order to create a more uniform wall and not create a single weak line.

• If you want to increase the tolerances you can use XY contour compensation in one of the pieces.

Post-Printing

Instructions

1. Disassemble the pedals

2. Annotate the position of the wire

3. Insert the potentiometer and its support, screw the nut into the potentiometer

4. Insert the new big gear and screw a countersunk head M4 screw to lock its position to the pedal

5. Assemble the pedal (with the spring)

6. Rotate the potentiomer shaft counterclockwise until it reach its end position

7. Insert the small gear by press fitting it into the potentiometer shaft, prefer to get the shaft cut horizontal

8. Solder the wires as the original position

9. You're done

How I Designed This

Measurements

I started by measuring the original specifications of the stock pedalboard: the potentiometer has a 180° movement and pressing the pedal make it doing an angle less than 90°. The deadzone should be also considered.

The clutch potentiometer measures 9.31kΩ.

Using the chinese potentiometers with either this remix or the original one should works, as long as mounted in the correct position, thanks to the fact the Logitech G29 has an auto calibration feature of the pedals done at every startup, within a certain range:

Design

So I designed the new gears with a ratio of 108:10 in order to get the desidered excursion of 80% of 270° (considering dead zone), this was not necessary as explained before.

There is neither travel limiter in my version nor the spring. The travel limiter probably set the zero position of the shaft, I do not think it could work against the pedal, and the spring it's probablt meant to zero the backlash, but I did not found any significant with this tolerances. Maybe a bit more tolerances is better for the health of the potentiometer.

This is entirely designed in FreeCAD