Brake pad problem (CL Brakes RC5+)
 

Can someone ( @JRitt I would be grateful) please help me find the cause of this problem. Respectively give suggestion for ways to solve it?

Equipment:
Yokohama AD08R, Stock rotors, Stainless steel brake lines, Castrol SRF fluid, Porsche lower control arm brake cooling vanes and CL Brakes RC5+ pads.

Situation:
3x 1 hour stints at Zolder Circuit, with 1 hour breaks in between.
A round is a bit above 2 minutes and has 7 hard braking points. This is what a round looks like (sorry in kph and unreliable speeds because of using iPhone GPS for Harry's Laptimer, still it should give an idea:
[ame="http://www.youtube.com/watch?v=H-0tS8JGzdU"]http://www.youtube.com/watch?v=H-0tS8JGzdU[/ame]


Result:
Pads after:
Worn down 5 mm, parts breaking off:

https://s32.postimg.org/tujdq6zyd/IMG_5055.jpg
https://s31.postimg.org/bbyybzbnf/IMG_5059.jpg
https://s31.postimg.org/vrsie3l5n/IMG_5044.jpg

Heavy pad deposits on the rotors:

https://s32.postimg.org/5s5cracmt/IMG_5052.jpg

Pads before: (One trackday 1 1/2 hours, but with Pirelli P Zero Nero GT and more cool down laps due to lack of oil cooler and before I switched to Castrol SRF.)
https://s31.postimg.org/68cqkyz63/IMG_4756.jpg
https://s32.postimg.org/sp6ss32b9/IMG_4763.jpg

And the rotors after those 1 1/2 hours, also slight build up, that when away after some days of street use:

http://s33.postimg.org/w3w5ozn7j/IMG_4751.jpg


This is not an RC5+ pad bashing. I was extremly pleased with them before AND during the event. They performed flawlessly, great stopping power, no fading, great feel etc. In fact I didn't notice when driving home either. Not until I wanted to drive the car 3 days later did I notice that the brakes felt weird (mushy) and it took a lot of effort to stop the car.

Since I took them off, I have cleaned the pads and put them back in. I have driven the car again (carefully and as test) and the deposits are lessening after some harder stops, they feel better and the stopping power has improved significantly again. Obviously they need to be replaced.

What next:
I guess it would be fair to assume it's a heat problem. I wonder why I didn't feel the deterioration during the event or at least on the way home?

I would really like to get CL Brakes pads again.

Is there a weak link here that I can fix, e.g. exchange the stock rotors? Could they be the culprit? Not dissipating the heat fast enough? Would the RC5+ work better with grooved rotors?

Is the 5 mm wear normal for 3 hours? Or is this a chain reaction causing increased wear once it went haywire? I assume some of the missing 5 mm are spread across the rotors now and that wear rate isn't normal?

I consider RC6, but read they can cause sparks that damage paintwork. Also I've seen videos where they make horrible noise for street driving (the RC5+ are delightfully quiet). I also consider the RC6E but read they make a lot of dust that cake up (the RC5+ were very low dust). I use the car for spirited Sunday drives, track and occasionally daily when the weather is nice.

Basically I would prefer to stay with the RC5+ what can I do that doesn't cost a fortune to rectify this? (No major cooling mods, that I would rather put forward to the Sprint kit eventually). Would a swap to other rotors helps? Are there anything obvious in driving technique that would cause this, that I can change?

You need more brake. If you're just mashing the brakes, and sitting on ABS, you'll always get a similar amount of braking via ABS, even if the pad is fading, until the pad is so faded you cannot engage ABS.

5mm of wear for 3 hours of driving is actually pretty low!

Are you running the same pads front and rear? How much are the rear pads wearing down?

Did you have the nannies turned off? If not, that could well be part of the explanation - VSC even in sports mode will hammer the pads to the point where they will overheat and break up like that especially in concert with ABS.

"More brake" as in BBK? Unfortunately I don't have the finances for that at the moment. An AP Sprint Kit is on the wish list. I try my best to avoid ABS.

No I am stock pads in the rear. Maybe it causes a brake bias problem?

5 sec TRC off, no pedal dance. Maybe the Electronic Brake Distribution is playing a part?

1 hour sessions on stock size rotors and not totally destroying the pads is impressive. IMO you'll need a BBK kit for those longer sessions, or at the very least a pad that handles more heat.

I had front pad overheating issues on an Evo when I ran a less aggressive pad on the rear. Coming into this car I read about everyone having brake cooling issues on the front and therefore upgrading front calipers. I decided to run a more aggressive pad on the rear than the front to see how far I could take stock calipers. This moved bias from about 65/35 stock to 60/40(you possibly went 70/30?). I've only done 2 track days at an admittedly intermediate pace, but the brakes had no issues and felt amazing. Something to try possibly.

Yes, that sound like a good tip that makes sense. What pads do you run?

Raybestos ST-45 front and ST-47 rear.

That causes a big problem. The front bites much more than the rear, so by the time you're locking up your fronts, the rear is barely even doing anything.

**Edit**

Just realised you meant the pad difference is a big problem. I interpreted it as the not using pedal dance.

Would you recommend a more or less aggressive pad in the rear (with pedal dance, and stock brakes)?

**Disregard below (answer to pedal dance)**

What can I say... I am a scientific kind of person. Without evidence, I won't follow advice blindly. Then I'd rather make my own experience. :D

I did read many threads about the pedal dance and decided not to use it on purpose. I found it to be too much voodoo and hear-say, with lack of real documentation or telemetry. Add to that that people experience other kinds of phenomenas like lack of braking at all ("ice mode") and I decided to leave it on.

To be honest, I am still very confused about Electronic Brake-force Distribution actually works in practice. Based on how the system is theoretically is supposed to work it would appear that it should be an advantage. Here is the description from scion.com:
In theory it would mean that it should keep the balance optimum. And even increase brake pressure on the rear if the front is about to lock up first.

It would appear that it is not working as intended? Maybe the system is just as crappy as VSC which seems to have too slow processing power or just lousy programmed. More expensive sport car brands have VSC that actually works (think Ferrari or even Formula 1 cars). But maybe it's the same for EBD? Maybe the intention is good, but the system reacts wrong/too slow or it is set up overly conservative to avoid any risk of the rears locking up first?

I got into a massive slide under trail braking. I was actually puzzled what caused the slide until I saw the video at home (unfortunately I forgot to press record on my foot cam in that session, but you can still see my foot on the brake).
[ame="http://www.youtube.com/watch?v=atS7q8UDglg"]http://www.youtube.com/watch?v=atS7q8UDglg[/ame]

I am still not entirely sure what I did there. Maybe I was just breaking too hard. But the rear brakes must be working too or I should have been plowing instead? Or it's just the weight transfer at play?


Still very confused and still don't feel I have the complete picture or information. But now I have my own experience that will warrant turning it off next time and see if it makes a difference for me. :)

With all that said, would you recommend a more or less aggressive pad in the rear (EBD off, and stock brakes)?

Thanks for you help Mike! :cheers:

Isn't best choice to have same compound both front/rear?

I am going to try out Ferodo DS 1.11 all round and Tarox F2000 rotors up front. Will report back if it makes a difference.


What a shame, I liked the RC5+. Will definitely get them again once I can afford an AP Racing Sprit kit.

So long RC5+, so long! :cry:
[ame="http://www.youtube.com/watch?v=wYBlXEuC9ms"]http://www.youtube.com/watch?v=wYBlXEuC9ms[/ame]

I run the RC5+ on an Essex Sprint Kit. A word of warning - it is not a good street/track hybrid combo! The sintered pads expand a lot when they heat up, so are made smaller to allow for this. The CP8350 caliper has no retaining clips so this means the pads rattle around a lot on the street. They are also quite noisy and difficult to modulate when braking lightly under 15mph (yes they are bedded). Also, with the harder compound I find it very difficult to heel-toe unless almost threshold braking. Not a big issue on the street, but it is good to keep the practice up.


On the track though, its a different story. These pads take a bashing and just keep asking for more. Awesome feel through the pedal with pedal pressure as opposed to travel controlling the amount of braking.


I now run Carbotech 1521's for the street - lovely pad, but I wouldn't track it.