Porsche Enthusiasts Club Forum

Posted yesterday about my miserable brakes. Well today they are fantastically brilliant. Rummaged around on the internet and found this article:

http://www.winbrake.com/training_lowpedaldiagnosis.html

went to Halfords this morning and bought three more flexible hose clamps (the steel ones not the plastic ones)
put car on stands and took wheels off again
clamped each hose near the end furthest away from the caliper to minimise hose variable (but not too near don't want to damage the rubber near the crimped end)
sat in car pressed brake pedal - like concrete no movement at all - great that means master cylinder OK and no air in the metal pipes.
started engine tried brake pedal again - tiny tiny amount of squish - metal bracket supporting the brake pedal assembly at the booster end flexes a midge, but only tiny, no cracks of failed welds in the bulkhead or pedal bracket assembly. OK I can live with that
then - remove clamp from each brake caliper in turn and see what it feels like at the pedal, then put the clamp back on so I am only testing one caliper at a time
Each front brake feels like concrete with the engine off and engine running - no movement at all - good
Passenger side rear brake feels slightly squishy but only a bit with engine running
Driver side rear brake feels very odd as though its leaking but no fluid anywhere. Took caliper off took it to bits, no leaks at piston, cleaned and greased sliders put it back together again. Bled it, Still feels odd.

Some of you may have guessed by now what is wrong...

When I replaced my rear wheel bearings I didn't take the rear brake pads out, I just looked at them from the pin side to see if they were parallel and even - which they were.
Took them out completely and they had worn at an angle inside because of the discs wobbling because of the worn bearings. Fortunately I had a set of brand new OEM porsche rear pads that came with the car (found in the spare wheel well). Put them in,
felt brakes - like concrete, engine on, still like concrete.

Popped wheels back on

Took car for a cautious drive - brake pedal movement is perfect - instant bite, feels really good.
Went about five miles with lots of gentle braking. All feels briliiant. Now for the acid test

Up to @ 70 ish then stand on the brakes - my eye balls nearly came out!
Now I know why 944 brakes work perfectly well on 928s as long as they are set up correctly.
So thanks for the replies and a big thanks to winbrake for the 4 clamp idea - makes diagnosing brake issues very straight forward. Hope this helps someone else struggling with duff brakes.
Time for a proper test....

Good tip about the hose clamps .