The steering wheel in NASCAR cars is removable for multiple reasons. The primary reason is because it makes it much easier for the driver to get out to the car. Before removable steering wheels, because the doors to NASCAR cars do not open and the inside is very compact, a driver had to maneuver their body in many different ways to slide their legs past the steering wheel to get into and out of the car. The removable steering wheel makes it much quicker and easier. The removable steering wheel also is used because in case of an emergency it makes it easier to remove the driver from the car. The steering wheels are also commonly known as quick release steering wheels.
Safety is the most important reason for having removable steering wheels. Whenever a crash occurs during a race and the driver is unconscious or needs help being removed from the vehicle, the removable steering wheel is extremely valuable and helpful for getting the driver out of the car. Before the removable steering wheel, it was difficult to remove drivers that could not get out of the car themselves. Oftentimes before the removable steering wheel, because a driver had to squeeze themselves into the tight fit, it was dangerous and difficult to try and pull them out without causing more injury.
The non-removable steering wheel also made it difficult to remove the seat belt because of its location and cutting the seat belt without causing injury to the driver was extremely difficult. The use of the removable steering wheel in NASCAR cars has helped with the survival of many drivers in extreme crashes.
NASCAR removable steering wheels are generally found in two different designs, hexagonal or splined hub. They are also found in both steel and light weight aluminum for most three-bolt mounting patterns. In general the design of the steering wheel that a driver has is based on their preference and what is most comfortable to them.
In general, the removal and attachment of the steering wheel is done by the driver. The driver will remove the steering wheel and give it to a crew member to get out of the car. The driver does have the main responsibility of attaching the steering wheel, but crew members often try to make sure that before the race starts the wheel is properly attached and locked into place. The driver does so by properly locking the hub on the wheel onto the steering shaft.
Drivers however, do understand that in the end it is their responsibility. For example, Dale Earnhardt JR. a famous and successful NASCAR driver, said that he is the one that gets into the car and straps himself in there and puts the steering wheel on. He recognized that it is his job to put on the wheel and make sure it's on. The drivers are responsible for checking that the wheel is on and if they forget to do so or they put the wheel on poorly, problems ensue.
The problems that come with removable steering wheels are that at times the wheel is not locked in. At the times where the driver does forget to lock in the wheel or do so poorly, then most likely the driver will pull on the wheel and remove it and crash. Unfortunately, this has happened before in NASCAR racing. For example, in 2016 Jimmie Johnson, another successful NASCAR driver, forgot to lock in his steering wheel and during the race he accidently removed it and the end result was a full-speed crash. Luckily, in this instance, injuries were avoided, but oftentimes that is not the case.
Even if the driver is able to avoid crashing, the removal of the steering wheel during a race will cause the driver to lose laps and their position in the race because they must stop racing and reconnect the steering wheel before they can continue. Either situation is not ideal for the drivers. Although these are problems that come with removable steering wheels, they are easily avoidable as long as everyone does their job. Therefore, it is accepted throughout the NASCAR community that removable steering wheels are very important to have in all NASCAR racing cars.