I have a 1996 Rover 825 SLI Auto with ABS. My brake pedal is nealy touching the floor before I feel strong breaking. I can feel slight breaking as I push the pedal down, and indeed this will stop the car. At about half way I feel the pedal give a little before travelling further.
There are no leakes on the system. I have checked the break hoses to see if there is any ballooning when the brakes are applied, but there is not. I have puchased a second hand master cylinder which has made no difference. The whole system has been bled (not pressure bled) to remove any air.
All of this has made no difference.
I have had the original master cylinder checked out and it is beyond repair.
It is possible that the second cylinder is also u.s.
So, how do I check the sytem to eliminate any other possible causes before I spend over £200 on a new master cylinder. Could the problem be something fairly simple that everybody is overlooking.
Regards

Terry Last, July 2008

hi Terry, It does sound like a duff master cylinder, (there is no spring on the rear piston) its a normal sliding caliper, when you bled the brakes did you bleed them in this sequence? L/H rear-R/H rear-R/H front-L/H front and you would need to do this at least three times.
The master cylinder is a dual channel device, the primary section is for the R/H front & L/H rear and the secondary for the others,when you apply the brakes the primary moves first and then due to hydraulic pressure it moves the secondary but if the seals on the primary section have failed/failing the secondary will only operate in the last bit of travel, but when you bleed them there is less fluid resistance and so the primary might work near to normal.
With brakes I would never trust a secondhand part unless it came with a certificate that it had been at least pressure tested or better overhauled.

nigel, July 2008

Hi
Have you checked the rear brake spring's ? If one is snapped the rear cylinder piston's have no resistance causing your brake pedal to travel to the floor.

paul, July 2008