gu patrol brake fade

Submitted: Monday, Jul 26, 2010 at 22:56
ThreadID: 80332 Views:4370 Replies:3 FollowUps:0
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gday all suspect this may be normal patrol fault but have an issue with the old boys 98 gu patrol wgn the brakes pull up up ok but fade if you hold pressure
we have replaced the master cylinder twice pads/rotors all good & wheel bearings have been serviced aprox 3 months ago & rechecked recently
the fault occurs hot or cold any thoughts thanks tom
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Reply By: Olsen's 4WD Tours and Training - Tuesday, Jul 27, 2010 at 07:30

Tuesday, Jul 27, 2010 at 07:30
checked the booster?
AnswerID: 425354

Reply By: Andrew - Tuesday, Jul 27, 2010 at 14:45

Tuesday, Jul 27, 2010 at 14:45
Can you explain the problem a bit more?

Fade happens when the pads get hot and lose their ability to grip the rotor, pressing harder doesn't help and the braking just gets worse as they get hotter. Eventually the fluid can boil and the pedal goes to the floor.
Causes:- cheap pads, riding the brakes, sticking calipers causing the brakes to drag.

If you are not losing fluid a sinking pedal usually indicates an internal leak in the master cylinder seals. This can also allow the pedal to be pumped up then it sinks again under pressure.

A sinking pedal under very light brake pressure id almost always the master cylinder seals.
The seals don't have to be worn out, they might be contaminated with dirty brake fluid preventing a good contact with the cylinder walls.

A good flush with good quality brake fluid is a good starting point.

If the pedal feels spongy then you could be pulling air in through a faulty caliper or wheel cylinder seal, which doesn't always show up as an external leak. This can be caused by fitted new pads or linings and pushing the pistons back without making sure they are clean.

Faulty boosters usually mean you have to press harder to stop the vehicle.

Hope this gives you a somewhere to start


AnswerID: 425386

Reply By: Member - Morry H (WA) - Thursday, Jul 29, 2010 at 00:02

Thursday, Jul 29, 2010 at 00:02
hi tom clamp the flexable brake hoses with multi grips then apply brakes,with engine going if brakes stay firm master cylinder will be ok .air is common after fitting new pads getting into load sensing proportioning valve. a good presure bleed maybe needed if you dont have the gear to do the presure bleed most brake places will do it for you cost around $40 . also the flexable brake hoses do expand under presure when aged and you will get brake fade as well to fix get new ones fitted gu brakes are not as good as the old gq series imho regards morry
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