Low Brake Power When The Engine Is Switched Off

NRX · November 15, 2011

Well, I"m not sure whether this is normal or not, this happens with my FB13, and my first ever car. Brake power is fine when the engine is running, but relatively low when engine is off. does something have to do with the brake pump, is it driven by the engine pressure or vacuum. ?

When I went for the service the service guy said I'll have to change rear brake shoes like within another 1000Km, in addition my hand brake is low, won't stop the parked car in a slight hill. I noticed the rear brake shoes thickness was about 3mm. Hoping to replace the brake shoes soon, is it a costly repair ? how much roughly ?

Thanks in advance

Edited November 16, 2011 by NRX

NPP · November 15, 2011

the brake booster (i think) is turned off when engine is not running. while driving if the engine turns off, you have to stop the car with one good press of the brake pedal. if you press again it will be hard and you must use a lot of force.

rear pads will normally cost less than 5k and is around a 30 min job. price depends on what pads you buy.

miniace · November 15, 2011

This link will educate you

http://www.kfz-tech.de/Engl/Bremskraftverst.htm

MINIACE

Edited November 16, 2011 by miniace

Sylvi · November 16, 2011

NRX,

NPP'S Post is correct.

When the engine is not running there is no Vacuum build up on the brake booster tank. so definitely there will be very low brake efficiency, Most of automobiles are build with vacuum assisted brake system. Your brake paddle you will have to press very hard to obtain brakes of your Vehicle.

Members, Above is according to my knowledge please correct me, if it is wrong statement of mine.

Sylvi Wijesinghe.

maheshw · November 16, 2011

Hi NRX,

as Mr Sylvi,NPP,Miniace state it's correct that these model of vehicles are coming with vacumm type brakes.its ON only when the engine is switch ON.When engine get off suddenly same time the breaks get off. as NPP said its work fine only for the first time after the engine off. after you need to give a big power to press the padel.

If you feel that your brakes are low you can only check it when the vehicle is moving with engine on status.my opinion is not to do this because you will get failed to stop the vehicle in a immidiate situation.

Others pls correct us if wrong.

Good day....

fonfe · November 16, 2011

The word you guys are looking for is servo assisted.

A petrol engine uses the vacuum from the inlet manifold for the brake servo.

A diesel uses a brake pump that creates a vacuum which is normally driven off a small camshaft lobe.

(range rover sport and disco3 tdv6 engines have a recall for this, due to the non return valve failing and causing the servo to fill up with oil, if you have a tdv6 remove the vacuum line and put a straw down inside the servo to check if you have oil inside it. if there’s oil you need the modified valve and the servo replaced)

Your handbrake may use your rear brake pads or it may use shoes which are inside your rear discs and will be the same sort of setup as if you had rear drum brakes.

Your hand brake may just need adjusting. So I would look and see which type of handbrake setup you have and then adjust accordingly. if you still have 3mm of pad left and you have a pad handbrake setup this should still hold on a hill so it needs adjusting.

NRX · November 16, 2011

Sorry for the confusion everyone, the rear brake is drum brake and the brake shoe still holds about 3mm (at the thinnest point, it's uneven from top to bottom ) of the friction material

And thanking everyone who took their time to reply