cool carbon brake pads - day at the track review

[Fen335i]

Hi Guys - Just got back from a day at the track yesterday. A buddy and I installed Cool Carbon brake pads (along w/Motul 600 fluid) before the big day.

We were a little dissapointed in our braking performance. Matter of fact on the 2nd session we both started experiencing brake "juddering"...basically a lot of vibration when stepping on the brakes pretty hard. Once the pads cooled down they were fine, but this kept happening at each session. On the 4 hour drive back home, no problems at all.

Is this a "material transfer" issue? I never experienced this last summer at the track while using OEM pads. We followed the bedding process instructions as well.

Any suggestions?

[david @ eas]

There's a few things that could go wrong here, it's not necessarily the pads.

Material transfer can be a problem This can occur if ABS is activated during the initial bedding, or parking the car with hot brakes at the track without a cool down lap (or coming to a full stop while they're hot). This can also occur if the rotors weren't cleaned or replaced with new rotors from the old friction material prior to bedding.

This can also be caused by a non-uniform wheel torque or rust/foreign material between the rotor and the wheel. Also what you might want to consider, is that warped rotors may not necessarily show or feel different when they're cold. Make sure to double check everything to ensure none of the following happened in your situation.

[Fen335i]

If it's a material transfer problem, what do you do to fix it? Outside of buying new rotors...

[Fen335i]

We did have cool down laps after every session....and were careful not to use the emergency brake when parking the car after our sessions...coming to a complete stop when they were hot? Well, we did that when the sessions were over (kind of have to, to stop the car in your parking spot) ;-) But that was it...

[kevin@bavarianx]

You can do a lot of high speed braking from 80-25 until you just about cook your pads then cool off. If you see some discoloration on the edge of the rotor then it should be properly bedded in.

[JAJ]

Originally Posted by Fen335i

If it's a material transfer problem, what do you do to fix it? Outside of buying new rotors...

Drive the car normally and it will eventually clean up. Better still, get some proper track pads (for the next time out) and run them for a week or so on the street. That'll clean up your rotors in no time.

[Fen335i]

^ the problem seemed to go away once they were cooled down...our drive back home was fine. I was led to believe that CC's were better than OEM pads for track days. Granted, they aren't in the same league as a dedicated track/race pad...but I thought they would have stood up better on the track than they did. Maybe it's just this "material transfer" thing...and if they clean up after driving it a while they will be ok. But the juddering effect when braking from 120 - 50mph was a little unnearving to say the least.

[JAJ]

Originally Posted by Fen335i

^ the problem seemed to go away once they were cooled down...our drive back home was fine. I was led to believe that CC's were better than OEM pads for track days. Granted, they aren't in the same league as a dedicated track/race pad...but I thought they would have stood up better on the track than they did. Maybe it's just this "material transfer" thing...and if they clean up after driving it a while they will be ok. But the juddering effect when braking from 120 - 50mph was a little unnearving to say the least.

Material transfer happens when the pad gets too hot. Select earlier braking points and you can reduce or eliminate pad transfer without a significant increase in lap times (braking earlier unsettles the car less and you can carry more speed through the corner). If you want to keep the braking points you've been using, you'll need a pad that can handle the heat.

[Fen335i]

yea, maybe a more track oriented pad is what I need. I know there are a ton of threads on this, but what are the top 3 or 4 pads on the market now that are somewhat "rotor friendly"? Also, can I get away with keeping CC's on the rears (or even OEM) and just running a more track oriented pad up front?

[Bubbles]

I've ran CC pads in the past, they are good for about 20 minutes on my 335i. Ran pagids RS-19s with my M3 and they never faded in extreme temps in 45 minute-1 hour sessions. Of course the Pagids are 3x the price of the CC. You get what you pay for. Sounds like bedding was an issue. Cool carbons require a specific bedding process. Make sure the pads aren't in backwards, had a buddy run VIR with CC pads, he experienced major jutter due to the pads being installed backwards by a shop

That's why I change pads myself.

[Richbot]

Sounds like what can happen when you use two different and incompatible pads on the same set of rotors. Every pad leaves some garbage behind on the rotors, and that material can interfere with the operation of new pads if used on the same rotors, depending on the makeup of the friction material on the two different pads. This is why I carried enough spares to never use a different pad on the same set of rotors on the racecars.

I realize rotors are expensive on these cars, but it might be worth it to swap out the rotors with the pads and keep each set of rotors dedicated to each pad type. You can also scuff the rotors with a medium-grit sandpaper or even take a wire wheel to them if you want to clean them up a bit before installing the new pads.

[Gearhead999s]

Originally Posted by Richbot

Sounds like what can happen when you use two different and incompatible pads on the same set of rotors. Every pad leaves some garbage behind on the rotors, and that material can interfere with the operation of new pads if used on the same rotors, depending on the makeup of the friction material on the two different pads. This is why I carried enough spares to never use a different pad on the same set of rotors on the racecars.

I realize rotors are expensive on these cars, but it might be worth it to swap out the rotors with the pads and keep each set of rotors dedicated to each pad type. You can also scuff the rotors with a medium-grit sandpaper or even take a wire wheel to them if you want to clean them up a bit before installing the new pads.

We were told by the head engineer of PFC at a seminar to clean the rotors with Scotchbrite pads & brakecleen when changing brake pad compounds and after a race weeked as a normal part of maintenence.

[Fen335i]

Originally Posted by Gearhead999s

We were told by the head engineer of PFC at a seminar to clean the rotors with Scotchbrite pads & brakecleen when changing brake pad compounds and after a race weeked as a normal part of maintenence.

Interesting...maybe that will help. We didn't do any rotor cleaning prior to the CC pad install. We did follow the bedding procedure pretty closely however.

[Richbot]

Originally Posted by Gearhead999s

We were told by the head engineer of PFC at a seminar to clean the rotors with Scotchbrite pads & brakecleen when changing brake pad compounds and after a race weeked as a normal part of maintenence.

Yup, scotchbrite works too.

[kevin@bavarianx]

I run PFC Z-rated then switch over to their race pads and don't have to bed in as the friction film is almost similar.

[FruitCake]

where can i get PFC Z-rated pads?

[david @ eas]

Issue may not be material transfer, but try the following steps:

1) Try to re-bed the pads

2) Inspect rotors for localized material transfer

3) Clean rotors with green scotch brite pad and brake Kleen

4) If this is not enough, may have to become more aggressive and take light machine cut on the rotor surface

Hopefully any of those tricks work out.

[RENN Spec]

Originally Posted by FruitCake

where can i get PFC Z-rated pads?

You know where PM Sent

Most likely, the OP's driving ability is beyond the capability of CC.

[meile]

Originally Posted by Fen335i

Hi Guys - Just got back from a day at the track yesterday. A buddy and I installed Cool Carbon brake pads (along w/Motul 600 fluid) before the big day.

We were a little dissapointed in our braking performance. Matter of fact on the 2nd session we both started experiencing brake "juddering"...basically a lot of vibration when stepping on the brakes pretty hard. Once the pads cooled down they were fine, but this kept happening at each session. On the 4 hour drive back home, no problems at all.

I had the same problem on the Nurburgring with CC pads f / b, Motul 600 and standard rotors (335i e90 lci). At the end of the first lap there were a lot of vibration and reduced stopping power. However, I managed to complete a further 7 laps with this setup, but it was the weak link and I still have this problem when pushing the car and the brakes.

I have checked the rotors and they are fine.

Next year I will go for the m3 (e92). Unfortunately, they say the brakes could be a problem when tracking the M3, so I have to consider an upgrade here too. And here I cant understand bmw gmbh, why not offer a performance upgrade for the brakes like MB does for the c63 amg P P plus? Furthermore, you should not underestimate the aesthetic value of a good looking brake kit, compare to Porsche, MB and Audi.

[david @ eas]

The vibration issues mentioned can be caused with any brake pads if proper bedding has not been achieved and/or localized material deposits have been added to the rotor surface.

As it is mentioned that the rotors are OK, presumably with respect to pad deposits, it is most likely that the vibration noted is caused by one of a number of other possibilities.

There are many possibilities to cause vibration during braking especially after a brake change.

Any of these causes will be magnified under track conditions as heat increases and also using a pad with a higher friction level.

Issues may also arise if the previously used friction material has not been thoroughly removed from the rotor surface.

The possibilities have been discussed in a number of other posts.

Such things as proper and uniform wheel torque, foreign material/rust between wheel and rotor or between rotor and hub, warped rotors, installation errors and wear issues in suspension components should all be investigated as possible culprits.

Hope this helps!

[wilkoal]

+1 here as reported last year

http://www.e90post.com/forums/showth...03#post7465703

Key is about cooling down after 3/4 laps at maximum which you need to do anyway if you have a 335i.

I may give a try in the future to carbotech XP8 or XP12.

[aka_phox]

I have the same problem. I will re-accomplish the embedding process. Hopefully it works.

Question: how many braking sessions and at what speed should I do this in order to re-embed the pads?