I changed the MC because I was experiencing the same thing - a soft pedal. I had bled the system multiple times, and tried the Stillen MC brace as well, and nothing really changed the inherent feel of the pedal, unfortunately.

 

UPDATE

Heard a small squeal from left rear brake when stopping. Figured my pads were getting low and time for change. Rotors were thin, so ordered up new rotors and OEM pads.

Take pass side apart, find lower screw seized in caliper. Luckily, you only need to remove one caliper screw to replace the pads inthe bracket. Just remove one, pivot it out and pull the caliper off. So aside from screw seized in caliper, everything is new and lubed up as should be. The caliper bolt slides freely in the pad bracket..so replacing the caliper is not necesary.

Go to driver's side. Find lower caliper bolt boot GONE. How? No idea..but the boot that protects water from going into the pad bracket was missing so i knew it was seized. Hmm..never noticed that before. Well, not only is the lower screw seized in the caliper, but it's also seized in the pad bracket as well. I remove the top screw, and am about to pivot the caliper back with some leverage...but can't remove it. Hmm...might have the cause of my soft pedal here.

Found inner pad gone to nothing, but outer pads still had plenty of material suggesting this issue happened a LONG time ago. However, the seized pin prevented the caliper from moving, so every time you hit the brake pedal, it would take two pumps to fully close the pads on the rotor. One pad would simply push the caliper away from face of rotor slightly.

Since one side of my brakes were done, i swapped the rotors and put a pad with plenty of meat on it to buy me some time and put it all back together until i can order a new caliper.

Right away, with a fresh pad, the brakes are a "little" better. it's still soft, but there caliper still has a lot of movement with the one side only pushing.

Reman caliper from rockauto is ~ $50..so they are cheap. Got one ordered up. Next weekend (weather permitting), i'll swap on the new caliper, rotor and pads and report to if my issue has been solved. Crossing my fingers.

WHy i didn't catch it til now? I can really only see the outer pads, so when i checked both sides, they still had plenty of material left. I also didn't see the missing boot for whatever reason. Had i seen that a LONG time ago, i would have definitely suspected the caliper.

Makes sense with why pressing the brakes repeatedly HARD over and over improved feel for a short while. The pin was able to move "slightly" (that's how i rotated the caliper back) but it was difficult to move in and out. Aparently pressing the pedal hard pushed the caliper over a slight amount and improved feel until the pads wore down again.

I hope this is it...will report after changing the caliper out.

 

My update. I suspect the issue has something to do with the OEM calipers. I installed a Wilwood BBK with stainless brake lines a few weeks ago and the brake pedal is noticeably stiffer and harder. I kept the OEM master cylinder and now the brakes feel like they should IMO.

 

Update....


FIXED!!!

It was a faulty caliper. Can't beleive I let it go so long. Replaced it and car stops like a totally different car now! I actually have to relearn how to stop!


So, it was a rear caliper. The boot on the lower slide pin was missing and the pin completely seized in place. It wouldn't let the caliper move in or out to self center. As a resut, when I hit the pedal, only one pad made contact. The piston would extend and push the pad against the backside of the rotor. Over time, the pads wore and the rotor starting to have to push over. That's why I had to double pump. The pads wore away, but the caliper couldn't move so it could self-center. Basically, I was bending the caliper in on the seized slide pin!

Replaced it ($50 reman from rock auto) and everything is great again! Pedal is firmer, and more responsive, and the car actually brakes very well!

I'll snap some pics later of the old caliper to show the failure. There is some interesting pad wear.

 

And here;s the source of my aggrivation for over a year.



As you can see, the lower slide pin boot (right side) was completely missing and the pin was rusted solid. I could not free it. As a result, as the pads worn oddly, my pedal got softer and required double pumping to completely close the pads on the rotor.

Hope this helps someone out!

 

Thanks a lot for the updates! I really appreciate it. This puts me at ease knowing that flushing the brake fluid won't be a problem.

 

My pedal got noticeably better after replacing pads and rotors Saturday.

Now, I've replaced the pads/rotors several times on this car and it never made any difference, so I was very pleasantly surprised that the pedal feels much better now. The only thing I did differently that I can think of is this: While pressing the caliper pistons back in, I actually pushed them in until they bottomed out in the caliper. By bottomed out, I mean gently but positively reached the end of travel. Perhaps this pushed a bubble up out of the MC or something? I don't know. All I can say is the brake pedal is noticeably more firm and engages higher like it should. I didn't bleed the system. Hope this helps someone.

Edit: replaced fronts only.

 

Same issue here 2nd push feels great after the brembos went on

 

Interesting. I have put the stock calipers back on and this problem came right back. I blead a few times but never checked for a seized caliper. Horay for floating calipers!

I will give this a whirl before i go with SS lines or a new MC but i dont know when ill get the time to work on this.

 

The rear parking brake is actually a drum brake inside the rotor. I have a picture if you really want proof.

 

I actually had the problem come back. SOlft pedal and double-pumping the brakes again.

So i checked my calipers and sure as hell the other side had seized up. Fortunately I was able to free it up. Brakes felt great once again.

Seems now i need ot add regreasing the slide pins as regular maintainence.


Hopefully this is your issue. Seeing as i've had it happen twice, I wouldn't doubt it's a common issue.

What really pisses me off if I had the dealership look at the car, while under warranty, and report back that there was nothing wrong and the brakes are normal.

 

Just Curious, were they both rear calipers? Hope I'll get some time this weekend to check. Heck all I need to do it pull off a wheel (5 bolts) and then two caliper bolts. 7 botls makes it sound to easy. Wonder if I could just spray anti-seze or soak with WD-40 before I get to take a good look.

 

yeah. Both rear calipers. I've had no issues with my front calipers. They sit up high on the wheel. The rear calipers sit low, so they get wet constantly.

Despite my best efforts painting the calipers up to prevent rust, they just rust up like a ****.

I removed the caliper bracket, pulled out both pins cleaned the hell out of them and applied new high-temp grease.

Seems the lower pin is the culprit. I had both mine seize up.

 

Had a similar soft pedal on my '05 X.

Drivers side rear outboard pad had abraded down to the backing plate, eating the rotor.

Replaced both rear rotors and pads. Other 3 rear pads had about 50% life remaining. Lower slider bolt drivers side was seized. Badly enough that I couldn't even rotate the caliper down to pull the pads. Had to remove the caliper to get enough room to put an impact gun on the lower bolt to free it up, then pried it out with bar and vice grips.

Cleaned it up, greased it and replaced. All seems good now.

 

Here is my issue. Over the last week,heard a strange noise in front of car, and brake pedal would be firm then when halfway pressed go soft and grind. Replaced pads front and back,bled brakes and put in new fluid. Also turned rotors, and same feeling of no bite when hard braking with winding and grinding noises. No warning lights on in car...Mechanic said possible ABS Module or problems...Hooked to machine and nothing. Really don't want to take to dealership...