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Discussion Starter #1 (Edited)
I'm trying to figure out what (if anything) is going on with my brakes.

DBA4000 rotors with about 5 track days on them. I run Carbotech XP pads on track days and AX6 pads on the street. Both sets of pads have plenty left on them after 5 track days. All pads/rotors were bedded in during the spring.


On Monday I was at the track and didn't have any issues, but when leaving for the day, when I applied the brakes it felt like they something was grinding. I can feel increased feedback through the pedal and hear it too.

The first thing I did was to see how well I could isolate what was going on. I pulled the ebrake, and things sounded/felt normal. Applied the front brakes, not normal.

When I got home I verified that all pads had plenty left in them, and took a look at the rotors to see if there was anything obvious causing what I'm feeling.... everything looks normal as far as I can tell.

So the next thing I did was swap the XP pads out for the AX6 pads to see if there was any difference, and there wasn't. I re-checked all over the rotors to see if I could see anything making metal on metal contact and I came up blank. The tops have a thin coat of rust on them so I dont' think anything is coming down on the top of the rotor. The only time I hear/feel anything out of the ordinary is when applying the brakes, it doesn't seem to matter if its lots of pressure or just a small amount.

I should add that after changing to the AX6 pads, I took the car out and repeated the bedding process, but I didn't notice any change.

Any ideas guys? Maybe I'll order up a new set of rotors... but I wanted to see if there were other things that maybe I overlooked.
 

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Discussion Starter #2 (Edited)
So I figured out where my grinding was, but I'm not quite sure that to do about it. The caliper is coming in contact with the top of the rotor on the passenger side.

By the marks, it appears that the bottom part of the front caliper is coming into contact with the outer edge of the rotor under braking.

I removed the rotor and checked for any grime between the rotor and the hub... found none, cleaned and put the rotor back on. Because of the way the caliper attaches, there isn't exactly a lot of wiggle room to put the caliper in a different position. Up on jacks, it doesn't look like the caliper and the rotor come in contact. Suggestions for what to do?

Its odd to me that this seems to have developed after I've had the rotors on for almost 1000 miles, and have done a few track days.

Here is where they touch, only under braking (not my exact car/rotor)

 

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So I figured out where my grinding was, but I'm not quite sure that to do about it. The caliper is coming in contact with the top of the rotor on the passenger side.

By the marks, it appears that the bottom part of the front caliper is coming into contact with the outer edge of the rotor under braking.

I removed the rotor and checked for any grime between the rotor and the hub... found none, cleaned and put the rotor back on. Because of the way the caliper attaches, there isn't exactly a lot of wiggle room to put the caliper in a different position. Up on jacks, it doesn't look like the caliper and the rotor come in contact. Suggestions for what to do?

Its odd to me that this seems to have developed after I've had the rotors on for almost 1000 miles, and have done a few track days.

Here is where they touch, only under braking (not my exact car/rotor)

Are you loosing the wheel bearing?
And I must ask the obvious, the caliper is not falling off right?

As an aside, that's a very odd picture, since when is there a bolt and nut going through the front hub?
 

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Discussion Starter #4
Maybe a picture IS worth a 1000 words.

The contact is coming from the caliper assembly coming down over the top of the rotor.

Heres a view over the top:


Heres the view from underneath:


See how part of the rotor is wiped clean (no rust)? Caliper appears fine, at least I didn't notice anything wrong with it when I took it off. Was/Is always torqued down to 33.5 lb/ft with BT applied to the bolt threads. If I take off the rotor, there is a corresponding "squeeky clean and shiny" spot on the caliper where they touch. Also of note is that the rotor is not wiped clean all the way around, just over part of it (about 1/4 of the circumference)
 

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Did you get a rock stuck in there maybe? That's certainly odd with the contact point.
Can you get a better picture of the bottom similar to the top? I'd like to see where the rotor enters the caliper.

Take the other side off and compare the two rotors? Maybe one is larger than the other?
Hope that helps some.
 

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Discussion Starter #6
just a followup in case anyone happens on this thread at a later date. Re-cap:

Light grinding sound present under braking only. Pulled ebrake and no problems. Fast as I could go stop in reverse, no problems. Only showed itself under braking going forward.

Swapped pads - did not work
Swapped rotors front to rear - still not fixed

Noticed wear as shown in pictures. Tried to wiggle the wheel and see if it was classic symptoms of a wheel bearing going out - seemed solid.

Removed the wheel and inspected to see if there was any grinding. As far as my inspection was concerned, there was no grinding when I had the wheel off spinning the rotor by hand.

Checked all bolt torques to the caliper and the wheel bearing - everything solid.

Replaced hub assembly - problem solved!
 
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