Enry86cami

Hello to everyone, i'm building my chiron. I would like to test the gears before to complete the entire installation. How does the gearbox works? can someone explain it to me? In the car there is the gear selector and the lever for the drive/neutral/rear mode. is it correct? What should change between these modes? For example, -if I push forward the car when the "reverse gear" is engaged, what should happen? -how I know what is the gear engaged? -if the last gear engaged, what happen i if upshifting again? -could i insert the reverse gear if I am for example in 4th gear? Thanks