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Hi there. Last week i arrived home and parked my manual vehicle on my sloping driveway as i have in the same car for the last 3 years. 45 seconds after getting out of the car the car suddenly rolled backwards down my drive and crashed into a neighbours fence (it wasnt left in gear). Luckily no-one was hurt. I cant explain what happended but obviously the handbrake let go. I got a WOF only 1 week earlier and have now noticed on the WOF form it says PARKING BRAKE 38%. Is this number low?, is it possibly relevant to what has happened. Your advice is much appreciated. cheers Dallas.

Hi Dallas,
The brake efficiency is recorded as a percentage with the NZTA Wof rule below.
Parking brake
13. A parking brake must:
a) stop the vehicle within 18m from a speed of 30km/h (average brake efficiency of 20%), or
b) hold the vehicle at rest on a slope of 1 in 5.

Hi.....thanks for your reply. Yes i have seen this rule, but what does it actually mean in my situation? Can a handbrake 'let go' after a period of time and be considered compliant? Also my driveway is not as steep as 1 in 5 (11 degrees). cheers Dallas

Hi there.
It means that the hold percentage of your brake at the time of inspection was a higher than the passable minimum of 20%.
You would definitely need to have your vehicle looked at to see if something is broken- however if that was the case you should be able to demonstrate this. Handbrakes don't usually 'let go' as they are on a ratcheted cable system (unless a more modern electric system) and often independent of the main braking system. There are no rules or specs around how long a handbrake must hold for- but you would think once it's applied it needs to hold till no longer required.

Thankyou for your help.