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RRC Brakes - master cylinder problem - at wits end


MattMatt

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Any help would be appreciated eventhough I don't have an RRC but the brake system on my Series coiler are from an RRC hence the post in this forum. It has the early AP master cylinder with primary and secondary circuits but I can't get pressure in the front system.

The brakes were working fine but I had a piston in the front caliper seize so replaced the them in both front calipers with Bearmach stuff. After that when trying to bleed them I could get no pressure in the pedal so I assumed the master cylinder (new a few years ago) had gone. The bores seemed perfect so I replaced the seals firstly with B***part stuff (didn't fit well - jammed) but then with a kit from Rimmers. I get good pressure in the primary circuit but virtually nothing in the secondary circuit (furthest from the servo). Opening the bled valve and pumping the pedal slowly results in fluid going back and forth instead of pumping through. Bleeding in the normal way I don't get much fluid coming through.

There are no fluid leaks either from the master cylinder or calipers and I have triple checked the master cylinder seals and springs are assembled correctly

I have tried everything I know and it's not working. Any ideas what could be wrong?

BTW both front brakes seem to be connected to the secondary circuit and the rear to the primary instead of the conventional way but they worked perfectly before for many years

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I've very recently had the same hassle bleeding after an m/c swap. I don't have a bleeding kit/pump/system, and was working alone. At first it was braking at front only, nothing much at all at the rear. This is what I did.

First, I drilled a hole in a metal top off a glass bottle and ran 40cm or so of clear pipe into it, sticking the end of the pipe into a pool of spanky fresh brake fluid in the bottom of the bottle, I then fitted this lot to the nipple furthest from the m/c.

Then I selected an appropriate piece of wood for holding the pedal down with... then pump pump etc etc and hold pedal down, round the back under the truck and open the nipple to let what ever was there out, closing the nipple again as soon as anything happened (and quite a few times nothing at all came out).

At first (second, third, fourth, fifth and quite a bit more) almost nothing came - I too thought that surely a portioning or G valve or something had jammed, but I stuck with my pumpy pump pump as I had no spares or other working vehicle. Now and then I got something slightly more encouraging, a little bit of movement of the fluid in the pipe. Eventually I did wonder 'Am I dreaming? Is that pressure I'm feeling in the pedal?' Back under the truck (pedal held down by trusty piece of wood), open the nipple and Woosh, a fair amount of bubbly cloudy skanky and generally unloved fluid swept down the tube into the bottle. YES! After that it was bleed as normal, slow going by yourself but no worries at all.

Just like you, I'd swapped/repaired the front calipers then the m/c... then decided that somehow this simple system must be faulty or haunted in some hidden way. Turns out that it's just a drag to bleed - so you start to believe that something else's wrong. Stick with it and you're good.

Unless of course your shuttle switch IS goosed....

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Ahh - someone is a little more patient than I am. My wife was doing the pumpy(?!!!) thing and it was cold and wet so I didn't want to leave her there too long.

I will try again tomorrow with all the advice given here put into motion - tell you how a get on..........

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Ahh - someone is a little more patient than I am. My wife was doing the pumpy(?!!!) thing and it was cold and wet so I didn't want to leave her there too long.

I will try again tomorrow with all the advice given here put into motion - tell you how a get on..........

Lucky you for actually getting your wife out to help you, especially if it was cold & wet! If I ask my fiancée to give me a hand all I get is that look of "I'm busy, what do you want" so I have to go it alone :( There's no love for my Land Rover except from me.

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Buy an Eezibleed....

Put new front calipers on mine and bed the whole lot through in a few minutes.

But one thing in the post about fluid going back and forth; if manual bleeding, I always get my assistant (guess who) to hold the pedal down while I lightly tighten the bleed screw and then allow the pedal to return. Makes sure that fluid is pushed in as if full of air it is easier for the fluid to move back through the pipes than to come in from the reservoir.

Also try pushing the pistons tight back into calipers to reduce the overall volume (and some awkward galleries) you are trying to bleed.

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All done so many thanks to the contributors, advisers etc. I remade the front pipes so they were arranged as per the original RRC, checked the pressure failure switch but couldn't find anything wrong and finally filled and bled the system. Now the brakes feel hard and up to spec

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