Disc brakes : heat cracks

[Arun_D]

I am monitoring mine too as they're starting to look tired now. I think the PF08s put quite a bit more heat into the disc than the standard pads, as I am sure the surface crack propagation have accelerated since changing compound (in fact I don't even remember seeing them at all when I did the pad change). Fair trade-off for the performance

[NW76]

14 hours ago, Bentzion said:

Porsche doesn't manufacture ANY brake components.  Brembo/AP usually make all their OEM pieces.  PFC that are made for racing like the Brembo/AP are a whole different story.  PFC's claim to fame of ZERO DRAG is a ripoff of another company..But they work.

You don't need holes.  They were used in the 70's to allow the brake pads to outgas while very hot.  They don't do that anymore because most pads are "baked" to cook off all the excess resins.  The cracks you see are stress cracks from heat.  Grey Iron is Grey Iron...plus or minus a couple of points of carbon infusion.  Two piece rotors are better because they don't warp and can control heat better..usually.  Get rid of ANY silicon based fluid and RUN ONLY AP racing fluid...That will help a lot in consistency in brake feel.  After every heavy track day session completely flush the system.  That will keep your calipers working optimally.  Also, if you plan on a lot of track days then you should buy a rebuild kit and plan on rebuilding you calipers once a year.

You are right they do not manufacture and Brembo is their key supplier. What I meant is that they are heavily involved in development of the brakes and they consider "their" brakes (even if they are manufactured by a supplier) a critical component of their cars/brand equity. Nevertheless they still go to PFC for their racing cars ;-) (see Image below).

The change to a racing brake fluid was one of the first things I did. I meanwhile run the PFC fluid and I am very happy with it. Changig once a year will do for my use. I do a couple of track days and do not race. So far so good. I am very happy with PFC.

  

[Bentzion]

1 hour ago, Arun_D said:

I am monitoring mine too as they're starting to look tired now. I think the PF08s put quite a bit more heat into the disc than the standard pads, as I am sure the surface crack propagation have accelerated since changing compound (in fact I don't even remember seeing them at all when I did the pad change). Fair trade-off for the performance

most PFC pad compounds are considered in the industry to be cinder blocks.  They are quite aggressive.  You might consider a different pad manufacturer.  Call a motorsport supply shop and ask them what the recommend for street and track.  

[DK7]

@Arun_D

the crackes look not bad. imho ~ 50% lifetime still

Edited April 12, 2017 by DK7

[geartox]

After only 3 trackdays I have already now small heat cracks on the new disks, it's really "small", but I am surprised. Maybe I doing something wrong but what ? Maybe I brake too hard, or I don't let enough time between two sessions, but at this price... We will see.

[NANO]

Did you complete a slow, slow-moving ride, without touching the brakes before returning to the box ?

Did you let it cool before you start a new session ?

[geartox]

Yes a I do at least one complete ride at low speed and I wait at least 20 minutes between two sessions.

I monitor that now. I go to a new track day this Sunday, We will see if it's becoming worse.

 

 

[NW76]

@geartox do you have the standard one piece brakes?

[geartox]

I have the PFC disks sold by Komotec.

[NW76]

Heat cracks on the grooved PFC disc after 3 trackdays? Can you take a picture? 

You should imho not see any significant heat cracks at all with the PFC grooved discs as far as I know ...

[geartox]

I will take one tomorrow and share with you. 

[SamoL]

Regarding discs: bigger is not necessary better. For Elise I've bought plenty of different discs including a bit bigger two piece from AP Racing. Now I am using EBC's BSD discs. Not only they are cheap, but they are the only discs I was able to wear down to minimum thickness without resurfacing them.

Most probably BSD discs don't come in Exige V6 sizes, but what I wanted to say was that different discs might solve your problems. My car came with grooved two piece floating discs. And they work really well. That's why I'll just stick to them and not change them for bigger and theoretically better discs. I'm sure you don't brake too hard. I don't think that's possible

[geartox]

Feedback : I am really satisfied with the PFC pads and PFC front disks.  On the rear I keep the OEM disks but I have installed also PFC pads. I don't know if from running cost point of view it's better, but the life of the OEM pads is really short.

The next challenge for me now is to improve my skills for replacing the pads 

Easy to remove pad pins but not really easy to put them back. I don't know if there is a trick or if I don't have the good tools... 

I plan also to try to replace the disks myself.

[NW76]

Nicolas: I would change to the complete PFC setup on the rear as well as soon as your OEM discs are done. The life of the PFC setup is much longer than OEM and it isnt that much more expensive if you do it, when you have to replace the discs anyway... 

I am also very happy with the PFC for me probably the best upgrade I have made on the car... 

[geartox]

another point based on my experience (two pads per disk, one "internal", one "external") : the wear of the pads on the same disk, is not symmetric. And without removing the wheel, you can't see the wear of the "internal" pad. Just take care of that before a trackday. I bought an endoscope on Internet to check the wear on internal pads. 

 

[vd9]

3 hours ago, geartox said:

the wear of the pads on the same disk, is not symmetric

That's 100% correct. Normally under active use the inside ones are wearing out faster, as they are ventilated less. 

[W31SSN]

I'm on standard single piece discs with PF 08 pads at the moment, and the stopping power is great.

What are people's thoughts regarding the komotec brake package vs the seriously lotus kit?

 

[NW76]

The Kobra4 is based on a PFC system ... PFC is amongst the very best you can get and so is the Kobra4 - probably the best upgrade for me so far.

Dont know the other Kit btw 

 

 

[W31SSN]

Went for @Seriouslylotus front kit as one heat crack had reached the edge of the disc! As always prompt service from Dave. Super easy to fit, took me 10mins each side.  Off to Spa on the 13th to give them a proper workout.

 

[Arun_D]

Yummy. Definitely required for mine this year as the cracks in mine are approaching critical.

[MrP_]

Are there any disc options for those of us on 2piece, or is it a buy new bells job again?

[Seriouslylotus]

Yes disc rotas are available without buying new bells for the factory two piece brakes

[Arun_D]

@MrP_ I've done exactly that with Dave yesterday. New replacement rotors for the rear, which I also could have done upfront but gone for his floating solution as per @W31SSN above .

[sieger]

Out of curiosity, what minimum thickness should the rotors get to before considering replacement? I think from new the fronts are 32mm, and rears 26mm. 

Thanks!

[Arun_D]

That's right, the service notes state minimum thickness as 30mm and 24mm.