The simplest type of deadlock, such as these Cosmic locks (A), has a swinging arm that fits through slots cut in the door and door pillar. Another design is the Banham lock (B), similar to those used for house doors. It consists of a bolt that moves out to fit through holes drilled in the door and door pillar.
One of the main reasons why so many cars are stolen is that a thief, even if inexperienced, can force a standard car door lock in a matter of seconds, often using nothing more than a piece of coat-hanger wire.
In response to the growing number of car thefts, manufacturers both of cars and car accessories have developed a range of devices and techniques to protect your car. But many of these simply immobilize your car. The thief can still break into the car and steal the contents. A cheap solution to this is to fit a set of high-security locks known as deadlocks.
These are fitted in addition to the standard door lock, which means you have two locks to undo instead of one. In practice, users often lock just the deadlock and leave the standard lock open. This is just as secure as using both locks.
Rack bolt locks
Two main types of deadlock are on the market. One is the rack bolt
lock. This is usually meant to be fitted to house doors or windows, but many can be adapted to fit to a car. Some manufacturers even make this type of lock specially for fitting to cars – a locksmith will be able to tell you if they are available in your area.
The lock assembly fits inside the door and consists of a supporting tube inside which runs the locking bolt. The bolt has teeth machined along one edge and these engage with a toothed pinion. The pinion in turn engages with the lock, which is operated by a specially shaped key. When the key is inserted and turned, the bolt slides along the tube and emerges and engages with a hole or plate in the door pillar.
The other type of deadlock on the market uses a flat metal bar attached to the end of the lock. When the key is turned, the bar turns with it through 90° and locates in a slot in the door pillar. This type is usually operated by a key that looks like a conventional car door key.