Hi, you should first check if your clutch pedal axis on your wheel is working properly, it could just be a dirty pot that causes noisy input. There is nothing wrong in LFS regarding of any axis from any controler. If you let us know the model and make of your wheel and how old it is, might help to pinpoint the issue faster.
edit: you can use DXtweak2, DIviewer to check if your controler input axis are working correctly.