I hope that someone can help and give some advise. My Dad has a hyundai lantra 1998 and it failed its Mot because the handbrake did not hold.
The exact failure message on the MOT failure is:
Brakes failures: RBT park brake efficiency 10%.
Reason for refusal of a test certificate:
001 parking brake efficiency below requirements[3.7.A.10].
The mechanic has tried to fix this by replacing two brake cylinders(the car has drum brakes on the back) and he now says it needs a brake proportioning valve.
My simple question is I thought that the parking brake uses a manual system and when you pull on the handbrake it pulls a cable and moves the shoes onto the drums on the rear of the car.
I done a search on the internet about this proportioning valve and it says the purpose of this is to "regulate hydraulic pressure to the rear brakes during heavy braking to eliminate rear wheel lock up".
The statement where it mentions "hydraulic pressure" to the rear brakes is where I am confused as I thought the parking brake had no reliance on the hydraulic system as you could be required in an emergency to use the park brake in the event of a brake failure?