hello, my brake pedal travel is acting strange ? though the brakes work and 80 % the time the bite is towards the top, it seems and this catches me out ! the pedal will drop to half way down before effective braking is applied.this is clearly a sign something is a miss??? on pumping the brake it comes rite back up again ( thankfully ) is it air at a calliper? or mastercylinder o ring worn? servo ??? ABS module??. some pointers if anyone could help , bit of a mystery as to why its here and there ... bit scary to as u cant tell when it going to happen. over average of say 10 miles it does it 2 x .

 

Lots to test there. Another possibility is shot wheel bearings. After turning a sharp corner the give is the bearing makes the brake disc push caliper pistons back further than normal which takes more pedal movement to get in contact with the disc.

If you're notching up the miles they could be the cause - can be hard to diagnose since sometimes they don't show any give when wiggling by hand with the wheel off the ground.

 

Good point there , the rear passenger bearing is a bit rough and possibly as u say causing space to form between pad and disc. im trying to get the bearing sorted but local garages seem reluctant to attempt it.i hear its a difficult task. I actually hav the hub and bearing pre fitted to go on from another model same as mine. gc8 uk99

 

There is also a one way valve in the vacuum pipe to themself if it is stuck open it could cause similar symptoms to the ones you have.

 

im starting to think this valve may be the problem. when I reverse and brake the pedal goes nearly to the floor, would this be reversal of the vacume pressure at manifold escaping through the one way valve? then I pump brake 2 x and its at top again. I have tested the vacume after turning engine off and holding foot on pedal firmly , theres absolutely no shift in pedal height. the reservoir is full and no fluid leaks to be seen... can this valve be purchased ? im assuming it comes fitted pressed inside the hose ? I think this would be the first try at fixing.

 

Yes it's integral too the hose, you can feel the lump in the hose where it is. You can also test it, you should be able to blow from servo towards the inlet manifold with no restriction but you should not be able to blow from manifold side towards servo if that makes sense.

 

hi thanks ,ifi pull this hose of ,is it under pressure? it wont damage the rubber diaphragm inside the servo??... don't want to end up with no brakes at all !. other thing I failed to say is im getting a dull squeal noise from steering ? could this be connected in some way??? driving from Worcester last night I could feel a very slight vibration in wheel as the noise was apparent. thanks all