One day the pedal travel became wierd. This was completely out of the blue while stopping at a light and has been the same since (about 3 weeks ago). 1/4 of the top pedal travel is spongy and really does nothing, then it slowly ramps up to normal pressure by 1/2 pedal travel. By normal pressure I mean how the brakes used to feel and work at almost top pedal travel.
I can brake just fine but the pedal is noticably softer and i can forcefully push the pedal all the way to the floor (could never push past 1/2 way before). Braking is still strong however as I can still lock up the fronts intentionally.
I have semi metallic pads so for 1/4 of the days braking I am pushing a bit harder then normal when they are cold. But I dont know if that contributed to the problem.
Brakes have always felt randomly different, sometimes the brake is slightly stiffer than other times. Its been very subtle, other 240 drivers might not even notice it, and i presume its just the brake booster getting a little less/more vaccum at times.
I can hear sometimes a low toned clunk from the front left wheel area under moderate braking. I cannot feel a pulse or anything in the pedal when it happens. I am not sure if its my strut or brake. If it was my brake the only think i could imagine it being was the pad coming off the rotor surface and clunking back down when pressure was applied (big guess).
What Ive done:
Rebled the entire system (good bye motul racing fluid
).didnt seem to be any air. Procedure was carried out properly. Didnt help at all.Pumping the brakes when stopping seems to stiffen it slightly and randomly but it goes back to its its old self right away.
If the brakes are warm or cold the only thing that changes is how good they grab, pedal feel and pressure doesnt change.
With the engine off and pumping the brake it takes about 3 pumps to get to max pressure. But instead of the pedal being super stiff and barely moving it has 1/8 to 1/6 spongy travel at the top.
Im at a loss here because all these signs seem to point at a bad master cylinder. I would think a wearing master cylinder however would be a slow gradual process and my car only has 105k miles.... kinda early for a failing master cylinder.... rather hear your input before i go tearing it apart (something in the back of my mind tells me its fine).
Need help!