Losing one of the gears in your transmission is a sign of a serious transmission problem. If the reverse gear in your transmission goes out, you can expect to spend a significant amount of money repairing it. Rebuilding a manual transmission can cost several thousand dollars, so losing the reverse gear in your transmission is a big deal. There are several things that can happen that will cause the reverse gear in your manual transmission to fail.
Sometimes the gears in your transmission simply wear out over time. If your vehicle is old, or has unusually high mileage, you can expect parts to fail. The gears in your transmission can break, wear out and otherwise stop functioning due to age or lack of proper transmission maintenance. If you never check your transmission fluid, never have your transmission flushed and never pay any attention to your transmission until you notice gears have stopped working, you can be fairly certain that part of the problem is neglect.
Manual transmissions require that the driver shift the transmission from gear to gear. If the driver makes a mistake, especially at a high rate of speed, it can break one of the gears. In the case of the reverse gear, if a driver shifts from third or fifth gear, aiming for fourth and instead hits reverse, the gear is almost guaranteed to break.
A damaged synchronizer can make it very, very difficult to put your transmission in gear. The synchronizer's job is to keep your vehicle from going into the incorrect gear and prevent breaking gears due to improper shifting. If you are struggling to get your transmission into reverse, you may want to have your mechanic check the synchronizer to make sure that it is actually your gear causing the problem and not the synchronizer malfunctioning and preventing you from putting your transmission into reverse.
