When stopped at lights with medium pressure on the brake pedal, after 30-60 seconds the pedal almost goes to the floor, quickly lifting off the pedal and pressing down again brings things back to normal, it only seems to do this when the brake pedal is applied for a long time, and doesn't always do it. I've checked for leaks and the level in fluid reservoir, it does not go down, further evidence of there not being a leak. The pads have about 75% life left all around.

Based on this, and researching, I came to the conclusion that it was most likely the master cylinder, faulty seal, so replaced it, it didn't take long and I bench bled the new before installing, I then bled all the brakes, the old fluid was pretty bad looking, so got it all out and I'm good to go.

It seems to have fixed the pedal going down, but the brakes still don't feel great, I would say the feel exactly the same before I did all the work, but I was expecting that after a complete fluid change and bleeding they would be a lot more sharpish.

So, are the brakes normally on the softish side? I was wondering if it worth replacing the rubber brakes hoses, as they are likely to be worn as the car has done 193k.

Any advice welcomed.

 

 

Find a dirt road and do some aggressive braking to activate the ABS system a couple times then re-bleed the brake system. Doing this will purge air that might be trapped in the ABS side of the system.

 

Thank you both for some great tips.

I did purge the lines until new fluid appeared, I did this for all the brakes, front and rear, using the recommended order as found on this forum, I will clean up the slider pins and see if that helps. Not sure about the pads, I 'm the third owner, father gave son car and then we bought of son, the pads look pretty new but I have feeling he may have cheaped out on parts, I changed the oil and filter when I first got it and he had the cheapest filter you could find, also the cabin air filter was the wrong way around, and the engine air filter was the dirtiest I've ever seen, so I'm giving it some love!

I'll do the aggressive driving and get the ABS working, I remember reading something about that, so definitely worth a shot.

It's a hard one to judge, but it's nice to know that the brakes are kinda of on the softish side any way.

 

One more thing, what thickness should the rotors be if new? The existing ones look ok but I really need to measure them to be certain.

 

what helped more? bleeding the brakes or replacing the master cylinder seal? were you able to test them out independently?

 

I haven't had time to tear down the old master cylinder and bench test it. All I can say is that replacing the master cylinder & reservoir has stopped the pedal going all the way to the floor after you have continually applied pressure for over 30 or 40 seconds. The pedal has never gone to the floor whilst driving under normal circumstances, it typically did this when stood on the brake pedal on a red stop for any length of time, and didn't always do it. My wife also drives the car and it rarely does it with her, but I tend to apply more pressure at the stop light than her, I also drove a manual for 30 years in a hilly area, so old habits and all that.

 

Yes I was going to say that if the pedal travels to the floor over time with pressure applied, then it's probably a problem with your master cylinder. The system should hold pressure if everything is working right.

I overhauled my brakes about 3 years ago with EBC dimpled/slotted rotors, EBC redstuff, goodridge SS lines, acura legend front calipers, changed fluid and bled system and painted all 4 calipers/brackets (paint held up very well over the 3 years BTW). The pedal was very stiff for about a year after that and braking performance was like scary outstanding. Rotors are still good and pads still have 1/2 life left (which is ridiculous because I drive down a steep hill every day). The pads generate a lot of dust though. It's gotten a bit soft now because I'm overdue for a brake fluid flush again (and the bleeder screws I think are letting a bit of air into the system). I also never properly bled the air from the ABS system. I have a front caliper off now for service that I'm doing on the suspension and have noticed that the pins are getting a bit stiff and need to be cleaned and greased again.

Anyway I highly recommend the upgrades that I did (thanks again to Skirmich for the recommendations). I did the whole thing for about $950 from what I remember.

 

I put Red Stuff pads on the front as well as braided lines last brake change and they bite pretty well. Pads will definitely help with brake stopping power, if you feel any softness you need to make sure you've bled the system completely and if that doesn't resolve it do some ABS stops from ~ 45 mph a couple times.