Hi all,

Been a lurker here for some time and finally crawling out of the shadows...

So I replaced the front rotors/pads on my 2010 A4 with Zimmerman rotors and Akebono pads (kit I used). Installation went pretty smoothly (other than snapping in those anti-rattle clips! ugh). I haven't bleed the breaks yet or done the bedding (I've read to let the coating on the rotors naturally wear off before doing this).

I have a few questions at this point that I'm hoping someone can help with:

1. The brakes feel soft/spongy currently. I've heard that brand new brakes will feel soft for a bit until they wear in (and/or are bedded). Also wondering if this is because air was introduced into the line when I pushed back the cylinders. Thoughts on these being likely causes or other thoughts?

2. After ~10 miles of driving lightly so far, I can that the coating on the rotor is wearing more towards the center, less so in the middle and not at all seemingly near the edge of the rotor. Pic:

Imgur: The most awesome images on the Internet

Is this normal? It seems that the pad is making less contact toward the outside, as evidence by the coating still being in tact there. Does the pad naturally squeeze more towards the center and thus the coating wore more there? Or is this a result of needing to be bedded? Should I be concerned?


Appreciate anyone's input here. You guys know your stuff!

Thanks!
Dan

 

Brakes usually feel spongy if the system has been open and air is in the system or if water (condensation) is absorbed in the system. If you did not open the system there should be no air in it. Also did you spray the rotors with "brake clean" to get the shipping coating off of the rotors. The bedding process is to transfer brake pad material to the rotor. Based on your picture it looks like you have the some of the coating left on the rotors. I would suggest you pull the pads and scuff them up with some emery cloth. Also do the same with the rotors and get that coat off of them. Re-install and if you want bleed the calipers. Then do the bedding process. How to bed in your new brakes for street/urban driving - EBC Brakes

 

I've done a few brake jobs in my lifetime and even used the exact same kit as you did. BTW there is no bedding-in required for that specific kit. It will be a tad soft at first but it should pretty quickly feel better.

What concerns me is the uneven wear that you picture is showing. It almost seems like the caliper pistons are not moving properly (or slider pins) or maybe the brakes (+pads) have not been seated properly. I would examine the work you've done to be safe - it should not look like that.
Make sure the brake pads sit properly and the clips are where they are supposed to be. You did state that the anti-rattle clips did not snap in place easily (and they usually do pretty nicely) so I would re-check everything.

 

Thanks for feedback guys. To answer a few of the questions/thoughts that were raised

-I did spray down rotors and pads w/ brake clean before installing
-Didn't open up the fluid system so it wouldn't seem I should have air in there
- Did not bleed or do a forced bedding at this point

I've got about 150mi on the new brakes and still generally the same. Soft pedal w/ long travel. Most of the coating on the rotors has worn off but there is still a thin band on outside. Here's a few pics:

Imgur: The most awesome images on the Internet

Sheldon- Based on your comments and some other research I did...I tend to agree that something mechanical is to blame. The fact that the clips were so difficult also leads me to think those could be the culprit...but looking at them they seem to look correct. Any specific advice? Or any chance you could snap a pic of your clips?

I can get back in there and look into things but not exactly sure what I should be checking as everything went together OK (except clips).

 

I can see if I can grab a picture of my brakes tomorrow however I do have the S4 brakes - so a tad different but still use the clip from what I can tell.

Have you looked at the back side of the rotor? Does it look the same?
If the inner looks more even - your problem is most likely the sliders. Did you take them out, clean them and re-grease them?

If the inner also look like the outer side - I would blame the hydraulics. Something is causing the caliper pistons not to push properly. The spongy feeling you describe could be an issue with your brake lines or fluid. Did you hang the caliper on the brake line while doing the job? If so this can cause the brake lines to crack/rip and introduce air as well as cause leaks.

Anyways - I hope these pointers help you find the problem.