Electronic park brakes – an unnecessary complication?

Posted on May 24th, 2012 by Rob Marshall

New car buyers love their gadgets and a recent innovation is the electric park brake, which solves a problem that nobody thought existed.

The premise of the system is straightforward. Instead of the ‘olde world’ ratchet and pawl, a button operates the park brake electrically, which works in either of two ways. Certain applications use a sole electric motor that operates the handbrake cables but the most common method is to mount an electric motor to each brake calliper. When activated, they apply sufficient force to the brake pads that prevents the car from rolling away when stationary.

The system also bestows the car manufacturer with several advantages. Firstly, the system can be programmed to release automatically, as the throttle and clutch are applied, allowing the relevant companies to integrate and market their vehicles with a ‘hill holder’ facility. The system helps to reduce manufacturing costs, not only on assembly, by a ratchet and pawl not being bolted to the car floor, but also with no need for some companies to require different handbrake levers for right and left hand drive versions of the same car. The extra cost of wiring and the associated electrical hardware is likely to be negated by such savings.

Yet, there are downsides. In almost all of the cars that I have driven thus equipped, the electronic park brakes have tended to be rather slow-witted to both engage and release. The slow deactivation rates will not help the longevity of the clutch (and dual-mass flywheel on some models), because the driver does not have direct control over the park brake.

Naturally, there will be longer-term owners of the latest models that will disagree with me questioning these systems but they will be hit by additional repair costs in the longer term, because electric park brake systems require maintenance. Although the periodic replacement and adjustment of cables is removed on most systems, the majority of mechanisms require adjusting as the brake pads wear and replacing the pads themselves demands diagnostic software to operate the motors (see picture). Certain models tend to exhibit more serious problems with the brake either not releasing or re-applying. Electronic interrogation, just to find the location of the fault can be expensive and, on some cars, the brake calliper-mounted parking brake motor cannot be replaced separately, failure of which might dictate the replacement of the entire calliper.

The practical problems that the system introduces, should the owner be faced with either a flat battery or a locked-on brake, does not help their case. So, when the time comes for me to replace my personal five year-old car, I shall look for certain new gadgets but the electronic parking brake will be left emphatically off the list.

Electronic park brakes – an unnecessary complication?

Electronic park brakes tend to require diagnostic software, when carrying out routine maintenance. This adds to the cost of a scheduled service. Yet, DIY owners can purchase the equipment themselves, such as the pictured £196.00 kit from Laser Tools, which will adjust Volkswagen, Audi and Mercedes-Benz systems.