brake problems...is it me??
Discussion
hello anyone,
stuck new discs & greenstuf pads on last week, one caliper seized - got new caliper, went round all corners bleeding, nipple snapped off rear piston - new piston required.
got supposedly sierra 2.3d pistons, fitted with new shoes also both sides, bled system - spongier than a sponge from spongeville, no air in system.
....new master cylinder on today, still sponge city, no air in system.
am I missing something???
my only conclusion is that I may have the wrong pistons, they did look a tad different, that may not be reaching the shoes correctly??
the pedal will stiffen up when engine off, then after 5 seconds be floorable again, totally spongy when servo on.
is it me??
getting fed up now, the sun's out....
stuck new discs & greenstuf pads on last week, one caliper seized - got new caliper, went round all corners bleeding, nipple snapped off rear piston - new piston required.
got supposedly sierra 2.3d pistons, fitted with new shoes also both sides, bled system - spongier than a sponge from spongeville, no air in system.
....new master cylinder on today, still sponge city, no air in system.
am I missing something???
my only conclusion is that I may have the wrong pistons, they did look a tad different, that may not be reaching the shoes correctly??
the pedal will stiffen up when engine off, then after 5 seconds be floorable again, totally spongy when servo on.
is it me??
getting fed up now, the sun's out....
s3 rich said:
hello anyone,
stuck new discs & greenstuf pads on last week, one caliper seized - got new caliper, went round all corners bleeding, nipple snapped off rear piston - new piston required.
got supposedly sierra 2.3d pistons, fitted with new shoes also both sides, bled system - spongier than a sponge from spongeville, no air in system.
....new master cylinder on today, still sponge city, no air in system.
am I missing something???
my only conclusion is that I may have the wrong pistons, they did look a tad different, that may not be reaching the shoes correctly??
the pedal will stiffen up when engine off, then after 5 seconds be floorable again, totally spongy when servo on.
is it me??
getting fed up now, the sun's out....
stuck new discs & greenstuf pads on last week, one caliper seized - got new caliper, went round all corners bleeding, nipple snapped off rear piston - new piston required.
got supposedly sierra 2.3d pistons, fitted with new shoes also both sides, bled system - spongier than a sponge from spongeville, no air in system.
....new master cylinder on today, still sponge city, no air in system.
am I missing something???
my only conclusion is that I may have the wrong pistons, they did look a tad different, that may not be reaching the shoes correctly??
the pedal will stiffen up when engine off, then after 5 seconds be floorable again, totally spongy when servo on.
is it me??
getting fed up now, the sun's out....
I take it you mean the rear wheel cylinders, not calipers.
Is the pedal spongy or does it just have too much travel?
I wouldn't have expected the pedal to drop that quick once the engine stops I thought it should stay high till you start the engine and drop with constant pressure on the pedal as the servo operates, maybe someone else could confirm that????, It may be a servo problem.
If your servo is ok, then I once had a similar problem to this, the only way I managed to get the air out of the system was to open all the bleed nipples and push/wind all the slave pistons fully in, close the nipples again and then bleed as normal with the pistons held in using G Clamps, then remove the clamps on the slave cylinder closest to the master cylinder and bleed that one then move progressively to the furthest from the master cylinder.Its one of those things that you do because someone told you to and it works but you arent really sure why.
If its not either of the above it must be the master cylinder leaking past the main seal.
If your servo is ok, then I once had a similar problem to this, the only way I managed to get the air out of the system was to open all the bleed nipples and push/wind all the slave pistons fully in, close the nipples again and then bleed as normal with the pistons held in using G Clamps, then remove the clamps on the slave cylinder closest to the master cylinder and bleed that one then move progressively to the furthest from the master cylinder.Its one of those things that you do because someone told you to and it works but you arent really sure why.
If its not either of the above it must be the master cylinder leaking past the main seal.
flexi hoses are ok, forgot to mention i also changed the master cylinder, also as we have a ford garage next door to my work with a few 'old skool' types there who said when you bleed the brakes on old equipment you are pushing the boundaries of the master cylinder's working capacity & therefore knackering the seals - hence a new one.
will be having another go tommorow morning, failing that there will be a fairly low milage S3 on ebay 'buy it now' £200, & I will be heading towards the bullet-proof world of japanese....please save me!! (the wife can't stand false spoilers etc)
Richard
will be having another go tommorow morning, failing that there will be a fairly low milage S3 on ebay 'buy it now' £200, & I will be heading towards the bullet-proof world of japanese....please save me!! (the wife can't stand false spoilers etc)
Richard
what is the correct procedure for bleeding?
nearest fo furthest or the other way round?
Tried clamping off flexi pipes, problem with the front nearside - we found the new caliper on the front is not working at all, seems siezed - no movement in the piston at all? got that changed & fitted new, still have same problem tho, even clamping off front or rears.
whats the chane of the master cylinder (new) bieng faulty??
nearest fo furthest or the other way round?
Tried clamping off flexi pipes, problem with the front nearside - we found the new caliper on the front is not working at all, seems siezed - no movement in the piston at all? got that changed & fitted new, still have same problem tho, even clamping off front or rears.
whats the chane of the master cylinder (new) bieng faulty??
Was the servo piston adjusted to suit the new master cylinder ( perhaps TRY this if it is adjusted or after) jack the car up under the drivers side front and release the master cylinder from the servo about 5mm, as this will allow the master cylinder to be at a different angle and ensure that the master cylinder is backed off fully, bleed gently whilst the cylinder is loose but in any order and redo the cylinder up!.
Adrian@
Adrian@
Edited by adrian@ on Saturday 21st April 12:37
what would this achieve?
we still do not have any pressure in the system, bled the brakes twice fully now, definately no leaks, shoes adjusted upto drums ok, clean bled last time, no air at all.
does anyone know the exact part number for the master cylinder? would a slightly different one make a difference?
this one is a fiest diesel one, the only difference to the original was two of the threads for the front pipes, same diameter internal & external where it fits into the servo
we still do not have any pressure in the system, bled the brakes twice fully now, definately no leaks, shoes adjusted upto drums ok, clean bled last time, no air at all.
does anyone know the exact part number for the master cylinder? would a slightly different one make a difference?
this one is a fiest diesel one, the only difference to the original was two of the threads for the front pipes, same diameter internal & external where it fits into the servo
s3 Rich said:
clean bled last time, no air at all.
I assume the new m/c is the same piston diameter and travel as the original (20.6mm and 35mm iirc). You can't rule out a problem in the m/c which is preventing it from developing the line pressure on the front brakes, but it doesn't seem very likely. Far more likely imo that you simply have an air pocket in one of the brake lines, unions, m/c or calipers. This is simply a matter of bouyancy, the air will sit at any high point and can be very difficult to shift. You need to visualise the internals of the m/c, calipers, bias valve etc to work out where these potential air locks are and then figure out how to get air out of there. This is a very different problem to just flushing old fluid with new, which is all you normally have to do when you're servicing the brakes. This might involve unmounting the calipers to get the bleed nipples right at the highest point and then bleeding in that position, tapping the pipes to release bubbles caught in joints and unions etc. A tip that I don't really understand but people have said is effective is to apply the brakes hard, wedge the pedal down to hold them on, leave it overnight, then bleed them again the next day.
This is the method I have had to use over the last 20 years on S/griff/Chimp.....as Pete says, the air will stay in the highest point, if you change the angle of the car/master cylinder the bubble of air will find another high point.
Adrian@
For me this is the only way to bring up a dry system, when I have rebuilt a car for a customer,that has an ALL NEW system.
Adrian@
For me this is the only way to bring up a dry system, when I have rebuilt a car for a customer,that has an ALL NEW system.
Edited by adrian@ on Saturday 21st April 15:08
this is to pete & adrian: problem sorted!!!
adrian - you are fully correct
pete - if I had read this reply when you posted it you would have saved us an hour or so.
air does travel to its highest point as we all know, it is neccessary to take the calipers off to do a proper 'dry' bleed.
the nearside caliper bleed nipple is below the inlet - all along there has been an air pocket in caliper.... what idiots!!!!
also learned that 'eezi-bleed' kits work at thier best at 5psi, not tyre pressure!!
thanks to all who gave me pointers in this thread, a very good lesson has been learned today. they say knowledge is power, i would be very happy & able to help someone else in my situation now.
kind regards to everyone... see some of you at the next ashby follville in a few weeks hopefully!!??
Richard
adrian - you are fully correct
pete - if I had read this reply when you posted it you would have saved us an hour or so.
air does travel to its highest point as we all know, it is neccessary to take the calipers off to do a proper 'dry' bleed.
the nearside caliper bleed nipple is below the inlet - all along there has been an air pocket in caliper.... what idiots!!!!
also learned that 'eezi-bleed' kits work at thier best at 5psi, not tyre pressure!!
thanks to all who gave me pointers in this thread, a very good lesson has been learned today. they say knowledge is power, i would be very happy & able to help someone else in my situation now.
kind regards to everyone... see some of you at the next ashby follville in a few weeks hopefully!!??
Richard
Gassing Station | S Series | Top of Page | What's New | My Stuff