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Archive for the ‘BMW’ Category

Engineering Overkill part 2: BMW door locks

Posted by ifitsgotanengine on October 2, 2006


What can be improved on typical car door locks? After all, all they have to do is lock and unlock the car, either with a key, lock button, or remote.

Let’s look at the E32 BMW door locks and see what they added. Remember, these cars first came out in 1988.


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  • The doors can be locked and deadlocked. When deadlocked, they will not open from inside. This prevents a thief from prying the window open enough to get a slim jim in and pull the lock knob. The lock knob and all rods internal to the door are physically prevented from moving. This also prevents anyone not familiar with the system from unlocking the door, even with the key, as unlocking a deadlocked door requires turning the key in the unlock direction, lifting the handle, then turning the key farther.
  • Heated door locks. If the temperature is below 38 F and you lift up on the outside door handle with the car locked, a heater in the lock energizes for 30 seconds to melt any ice from the lock.
  • Inertia switch. If the car undergoes a shock of approximately 5g’s, all doors automatically unlock, and the hazard lights turn on. This allows rescue teams to more easily locate a wrecked car and gain entry.
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Posted in BMW, Engineering | 8 Comments »

Why do I love my BMW? Engineering overkill.

Posted by ifitsgotanengine on October 2, 2006

The picture to the right is a diagram of the E32 (1988-1994 7-series) BMWs’ windshield wiper assembly. What is not immediately apparent from this diagram is the level of attention given to the engineering of this seemingly mundane system.

To wit:

  • When in slow speed, the wipers will switch to delay mode when the car is stopped, picking back up again when the car starts moving.
  • The intermittent delay will vary with car speed, or can be user-programmed for any time interval from two to twenty seconds.
  • The windshield has heating coils built into its base which prevent the wipers from freezing to the it. These automatically power up whenever outside temperature reaches 38° F.
  • My favorite – Part #4 on the diagram above is a “pressure adjusting device”. It varies the wipers’ pressure against the windshield with the car’s speed, preventing the wipers from lifting or chattering at high speed.


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Perhaps the best thing about the wipers is that they just work. Probably 99% of the owners of these cars don’t know about any of the items above.

That is the mark of engineering excellence.

Posted in BMW, Engineering | 3 Comments »