Pad Deposits or...?

alanyluan

Just finished a track day this weekend with my new brakes (Akebonos and Carbotech xp10/8). I made sure to go through a proper bed-in process at the time of the install, but at the end of the track day when I looked at the rotors, I could see some "smearing". As far as driving feel, I never felt any wheel vibration under hard braking. So, I'm not sure if this is pad deposits, but I wanted to get some expert opinions...





Thanks!!

ban25

That's normal after a track day. You may need to get the rotors turned after several events, depending upon how hard you track the car. You could add some brake vents to increase cooling. I also recommend Castrol SRF brake fluid.

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alanyluan

Thanks! I was planning on street driving the car every once in a while in between track days and hoping the XP10s up front remove any deposits that may have formed. Other than that, I have the duct kit for the fronts.

2011 Nismo#91

Heat spots IMO.

"Heat spots (Fig. x) are a tell tale sign that your brake rotors have uneven brake pad deposits. How do they affect you? Heat spots will lead to brake harshness, vibration and reduced structural integrity. Heat spots on brake rotors occur when brakes aren't broken in (bedded) properly and the brake pad deposits on the rotor accumulate and eventually turn into a compound known as cementite. You don't want Cementite on your brake rotors. Cementite is compound that is very hard, overly abrasive and doesn't allow the rotors to cool properly. As a result, Cementite heats up the local area around itself growing in size and reducing the cooling capacity of your brake rotors.
Prevention: Properly breaking/bedding in your new brake rotors is vital to the longevity of the rotor. See our Brake Rotor Bedding Guide.
If this is caught early on, you can possibly remedy it by bedding in your brakes with a more abrasive pad, or resurfacing your rotors. If the heat spots are extensive, you will need to replace your rotors."
https://brakeperformance.com/inspect...brake%20rotors.

alanyluan

Damn, I hope not. I was pretty intentional/hard on the brakes during the bed-in process so I'm surprised if it still turned out that I didn't bed it correctly. And my brakes were smoking pretty heavily for a while afterwards...

Out where I live, it's hard to find an open enough stretch of road to go through the bed-in procedure without looking like a jackass. For those of you who live in suburb/metro areas, any recommendations on how you bed your brakes?

Also, how many hours of cold street driving do you think is necessary to remove uneven pad deposits?

2011 Nismo#91

Don't worry too much about it, it's pretty hard to bed in brakes for track duty on the street. Do the best you can, I have similar issues with bedding, early morning industrial parks work best. Driving won't really get rid of them.

alanyluan

Sounds good, and thanks for the suggestion! I'll keep my eyes open for any changes in braking behavior and just go from there!

obender66

Any update? I run into that too, but it all clears up in about 3 weeks of street driving. Trying DTC- 60 next time.
https://flic.kr/p/2jwxw9V

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alanyluan

Unfortunately I haven't gotten around to street driving nearly as much as I'd hoped. I have another track day tomorrow so we'll see how it holds up.

alanyluan

Took this picture immediately after a session. Definitely looks like hot spots, but still didn't feel any vibration under braking....

thekinn

do some regular street driving, couple hundred miles, normal braking with those carbotech on.. they may be harsh enough to clean the rotors for you. They'll sound like a freight train once clean.. but .. that'll give you a fresh surface to start with.

Did you by any chance switch from something else to the Carbotechs?

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Cyber370

I wonder how much of that is due to the fact the discs are slotted?

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thekinn

I talked to some Z guys at a track day yesterday (which was a pleasant surprise, since there are rarely many Z's at our local MI tracks). One, who is using the same combination XP10/8 said he was experiencing the same issue with deposits on the rotor. He contacted Carbotech, and they said it was due to excessive heat. He installed some simple brake ducts and the issue went away.

Another guy who was also running the same combo XP10/8 for the first time started getting deposits mid-day and was getting some vibration too. Braking performance was still there. No brake ducts.

It has been years since I ran Carbotech, but seeing and riding with the one driver getting vibrations made me remember experiencing the same in my Z. Might want to look into ducting or a different combo if the issue persists after cleaning the rotors up and re-testing.

I use Hawk DTC-60 front and Performance Friction PFC-01 rear. No issues with heat during my 20-30min sessions and rotors looking spiffy. Good luck.

Attached Images

IMG_3655s.jpg (482.8 KB, 19 views)

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alanyluan

The rotor/pad set up is brand new, installed (along with Akebono calipers) from the Z base brakes just a few months ago. I also have the 2" ducting and SS lines.

I'm aiming for another track day next week and am still getting my bearings straight with brake styles/management; I'll see how that holds up. Track season is almost over for me anyways so once fall comes around, I'll remove the fronts and inspect them/consider resurfacing for another attempt at proper bedding. I'll definitely look into other pad combos too.

SG4247

You have a ton of heat checks (micro cracks) in those rotors!

Might look them over closely...

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