The gearbox is the most important part of your transmission that converts the engine speed into torque. The torque is what moves the car forward. If you do not know what is wrong with your car, but you know it has something to do with the gearbox, or transmission, contact a professional who specializes in gearbox repairs. They can evaluate this complicated mechanism and repair it for you. Getting it repaired, or repairing it yourself, will add many years to the life of your car.