Ok... I will make the assumption that you are using windows ... So going back to my extensive experience with Racer(.nl):
Racer has an adequate amount of in-simulator adjustments for the end user to make (including a simple checkbox to switch between digital and ANALOGUE). If you were to use your Logitech G920 racing wheel with Racer(.nl) (and have the left pedal set as the clutch as is usually the default), and the problem that you describe occurs, it is solved in one of three ways:
1. Opening the Windows Device Manager, selecting your wheel/pedal set, and either re-calibrating it, or also locating a similar Digital/Analogue setting in "Properties" for example and making sure it is set to ## ANALOGUE ## .
2. Changing the key command (clutch pedal in this case, or "C" on the keyboard even) from processing the input as DIGITAL, to processing the input as ## ANALOGUE ## . You might want to ask someone else who is good with RoR configuration files about where this setting/line can be found for wheels/pedal sets. I no longer have a wheel/pedal set.
3. Try to find the setting in the software that came with your wheel/pedal set, if any, and ensure the clutch is set to Analogue.
As I've mentioned, this solves the problem when using the physics simulator Racer(.nl) so

I hope

it can be of some aid in setting the clutch right in RoR as well.
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