Mud-club
Vehicle & Technical => Defender => Topic started by: Terry.J on July 23, 2007, 22:15:18
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hi all
I've just finished rebuilding my frt axle and fitted new calipers/pads/discs/brake lines.
After bleeding it the peddle is nice and firm as you would expect.
Took it for a test drive and the brakes work but take a lot of effort and are not good and felt like there is now no servo assistance taking place.
Tested this by holding the peddle down with the engine off then starting it up. i know that usually you can feel the peddle being pulled down by the servo as the vacuum builds up. what i can't understand is that this side of the brakes worked fine before i took it off the road for the rebuild (4 months ago).
Iv'e pulled the vacuum pipe off the servo and put my finger over it. It is sucking but i'm not sure how powerful it should be (does anyone know).
The oneway valve is letting by very very slighty when i blow down it so i have ordered one but i'm not convinced this is the problem.
has anyone got any sugestions as i don't want to go out paying for servo/vacuum pump if this is not the problem.
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What you need to do is pump the pedal several times with the engine off, it should get progressively harder then as you start the engine the pedal will be sucked away from under your foot. If it doesn't then the servo aint working properly if at all.
Could it just be that your new brakes need to bed in before reaching their full efficiency? if so then take it ewasy on them until they bed in as braking too hard can damage them.
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yes thats they way i tested the servo. pumped first to expell any vacuum build up then started the engine but nothing happens.
it's not just a case of the brakes being new as i have experienced this before, it is much worse (like when your being towed with the engine off).
Don't mind changing the servo if thats the problem but can't understand how it would pack up just because it's been standing for a few months.
thanks anyway
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Just had a thought after writing that lasted message.
As it's been standing for a while maybe something in the servo has got stuck due to the spring pressure (i had this once with a clutch and had to take the gearbox off to unstick it).
Anyway just been out and gave the pedal a few good bangs (foot as high as you can get it and repeatedly jump on the pedal) and it now works a treat :D :D
Think it was probably some sort of seal stuck that releases when the pedal is pressed to exhaust the back chamber of the servo which in turn allows the vacuum in the front chamber to pull the pedal.