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Brakes not pressurising


Guest Phil Young
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One of those problems again where there's probably going to be 10 answers telling me to bleed the system lol...


Ok so here's the deal - my motocross rear brake was working well, albeit a bit spongy, then it just stopped working.


I've spend god knows how long bleeding it, replaced the fluid, replaced the caliper and still doesn't work.


I've looked for damage to the seals of the MC and LOOKS fine. Fluid is getting to the caliper but doesn't want to pressurise.


If I take the line from the MC fluid will freely flow out.


If I take the banjo bolt off the caliper it stays put. If I press the brake lever down it will come out slightly but only a spit.


I've bled it with a hose as well and all that's come out was fluid... No air.


Help please :(

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Bleed the system :wink: but after you have either replaced the MC or the seals.

If you have replaced the fluid and the caliper it only leaves the MC. The seals may be passing so you can bleed fluid through but not fully pressurise the system to operate the pads against the disc.

Worth a shot.

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I would look at rebuilding the M/C


for it to work fine then to stop you have a problem somewhere


if you was just replacing fluid and had got air in then I would have said it would be trapped in the M/C


no leaking fluid anywhere?

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The m/c is dead as stu and jrh said, the spongy and then dead are the symptoms. Brake hose and caliper never give a spongy feel like the m/c will

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Ok in that case... Universal master cylinders for dirt bikes are only a fiver. Might have a bash at that next.


Definitely no leaks in fluid anywhere.

Edited by Anonymous
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When did you last change brake fluids?

and front master?

The question is...


When did the previous owner do it. I would imagine a long long time ago.

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Sounds like fluid going the wrong way.

Clamp off the pipe and squeeze the lever. If the lever can come back and no fluid squirtimg out, it's going through the bypass port.

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