keep loosing brakes on corsa gsi xe

[michael squeak]

I've just done an c20Xe conversion on my corsa b gsi.
I put the 2.0 disks an calipers on which is probably theist common break upgrade ever. I bleed them up and got a really good solid pedal,

Then... As soon as I turn the car on I loose all breaks and the pedal goes to the floor!

The car has abs but no rings on the shafts. As I'm using big block conversion shafts..

I've unplugged the abs and this still does nothing..

Really confused now.. I tried changing the master cylinder but couldn't fine one with the same unions as mine. The breaks worked fine before conversion..

All help appreciated as I'm totally lost now

Thanks mike

[millworm]

not to good with brakes but sound like it's something to do with the servo if you loose the pedal when you turn on the engine.

[meritlover]

How are you going to pass an MOT as ABS light will be on. What do you mean loose the pedal? Is it not just the servo working? Disconnect and plug the vacuum to the servo off. Start the engine and the pedal should remain. Found be the xe pulls a greater vac than the last engine but I would have thought this problem would have been addressed before. Xx

[michael squeak]

when i turn the key on the pedal can be pushed straight to the floor...the servo works fine because it hard when the engines off.

[jimbob-mcgrew]

bigger engines having greater vacuum, that makes sense lover boy, your continual scientific cyborg knowledge always suprises me :P

whats the plan then mike ? if you switch the engine off on a downhill, do the brakes work like they should ?

is the vacuum hose sealing properly ?

what happens if you plug the pipe ends ?

anyway of restricting the vacuum to suit the servo level, if that's the problem ?

[michael squeak]

ive tried so many things its unreal lol

basically.

i can get a good pedal when the engine is not running. and pure fluid comes out the nipple.
then as soon as i turn the key i can push the pedal right down and i get a slight brake at the bottom.

checked vacuum pipes they are sealing ok. even changed it to be sure..

what pipe ends do you mean pal? the small thin pipes? ive capped them on both the big plastic pipe and thin pipe, that made no difference.

also checked the main lines for breaks /splits.. none there.

and changed the front flexis

the brakes were fine before conversion.

[cj949rpe]

If you are using worn discs with a lip on them the brakes will need to bed in. With the small force without the servo the pads do not flex. Once the servo activates the pads flex and the pedal sinks.

If the brakes do not bed in then the inner seal in the master cylinder could be leaking - this will not cause an external leak as there is an outer seal also.

[michael squeak]

tried the gravity bleed today but still the same..

would using standard 1.2 master cylinder and servo, lines and flexxis. thus removing my abs pump work?