Hi there, after 5,000 km including 500km of trackdays, my dealer diagnosed my non-ceramic disks are all 4 damaged …. Despite systematically cooling down after hard break… unbelievable. Are we supposed to replace the disks more often than the tires ? (I’m still on original Pirelli tires).
Any other one experiencing this?
(symptoms were : clear pedal vibration even at low brake pedal pressure; no cracks; brake cleaner did not help; does not disappear with road drive conditions; dealer claimed having measured them and all 4 are « veiled » but unable to tell how I could have induce this)
Note: I went thru the Porsche precision and performance trainings in Le Mans. No stupid drive.

 

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Your rotors are warped. It means that at the molecular level your rotors are not true anymore. That causes your brake pads to " thump " on the rotor from the uneven surface and gives you the experience you've described. You can clearly see on the picture you've attached : those rotors look like they've been through some serious heat cycles!
Is that normal? Perhaps it isn't,but that's what happened....

 

Before you spend the money first put a dial indicator on the rotor and check for lateral run-out. Not sure of the spec think its like.002-.003 ..If they are true it sounds like pad transfer. causes judder even under light pressure. id try bedding in a new set of pads in a different compound. what pads are you now running? carl

 

Agree with Carl. I tried to find the FAQ from Essex Brakes I used but couldn’t. But basically I had severe brake judder after doing so many track days on OEM pads, switched to race pads on cold rotors on the street to “clean” off pad deposits and judder was all gone.

 

Brake rotors don't warp - it's either runout (with uneven wear) or pad deposits. Make sure you understand the root cause before you change anything.

 

the best pad for cleaning rotors is Raybestos ST43s. we used them a lot when we ran lotuses . Two laps and the rotors looked new. They are a aggressive pad with a big bite friction of 58mu. Used to get them from porterfield.carl
https://www.brakepartsinc.com/raybes...formation.html

 

Can get them from Gyro disc now. They are their pad of choice

 

The rotors do not look like there's anything wrong with them. At least not from the pictures.

 

I had a similar issue on stock pads on my 991.2 when I pushed them extremely hard. It was pad deposits, and I sanded them off and swapped in track pads and I was fine after that.

I’d recommend trying just a track pad swap first and see if that will clean off the rotor face for you. Otherwise it’s a few hours with a die grinder with a set of sanding pads.

 

THese rotors do not warp. THe transfer layer was unevenly smeared on the rotors. and this is what you are feeling in the brake pedal. I go thru this at least twice a month.

 

what do you suggest I should do now?

 

If you do not want to use abrasive pads for awhile, you can clean off the pad deposits using Simple Green cleaner and 3M dish scrubbing pads (the green ones). Clean both sides of rotors on entire friction surfaces and then rinse with water.

Pads will need to be bedded again after this (brakes will be poor until you deposit a new smooth layer of pad material from bedding process, so be aware on street)...

Note: Don't do this with PCCB rotors...

 

I have similar issue. Put on more aggressive pads and hoping for the best...

Stock brake pads are crap and melt when they get to the pits, leaving deposits on the discs. Do not track on stock brake pads.

 

Were you running the OEM pads on the discs on the track? If so, that's the source of your problem. Regardless of what Porsche tells you, the stock pads are optimized for road use and NOT track use. Below is an article I authored about why running stock pads on track is a bad idea. In this article I discuss exactly what happened to your discs, which is uneven pad deposits. The pads are heated past their maximum usable temperature, which causes them to smear onto your disc faces in globs.

Can I run my OEM brake pads on the track?

While I'm at it, many here will find my article, "Essex Track and Racing Pad Owner's Guide" valuable as well. It will help you squeeze the most useful life from your pads.

Here is a link to the Essex Learning Center as noted by forum member gesmith55 above...lots of articles and videos that can save you a bunch money and headaches: https://www.essexparts.com/support/learning-center--faq

Here's an article on deciding between the various Ferodo pad compounds: "Which Ferodo Pad Compound is Right for Me?"

As for what to do about it now that you have uneven pad deposits. As noted, an aggressive set of racing pads can scrape the discs clean. When cold, race pads are extremely abrasive. If you only ever drove them around town, they'd chew your discs up in a hurry. They don't stick to the discs in an adherent manner until they get hot. Our recommended pad choice is the Ferodo DS3.12 for those on race tires/slicks, while the DS1.11 is a great choice for street tires. You can see the Ferodo pads that fit the OEM 992 GT3 calipers on our site here: https://www.essexparts.com/my-vehicl...)/Iron%20Discs

Try fixing your current discs before trashing them. If you try running some abrasive race pads cold and you still have judder, you can try a scotchbrite pad as noted above by GrantG. That may be enough to knock down the high spots and eliminate the judder. It's better to do it soon however, because the more layers of pad material you lay down on the discs, the harder it is to remove. If that doesn't work, move to a low grit sandpaper and try again.

Sometimes even sandpaper won't remove the high spots if they're too far gone. If you need new discs, don't waste your money on OEM if you plan to keep tracking the car. I'd suggest our AP Racing 2-piece J Hook Discs in the OEM sizes. They are a direct replacement for the OEM units. They run far cooler than the OEM discs and will help prevent your pads (and fluid) from overheating under track duress. The metallurgy is also far more crack-resistant, and our customers are getting far more miles out of them any OEM disc has a prayer of achieving. They're a bit more expensive than stock on initial purchase, but you save money over the long-term since you're changing your pads, discs, and fluid much less often. You can see them here:
Front= https://www.essexparts.com/essex-des...iron-front5481
Rear= https://www.essexparts.com/essex-des...91gt3iron-rear

Below is a video I shot years ago that shows how easy it can be to peel a layer of pad material from a disc face with race pads run cold.

Feel free to reach out via PM if you need further assistance...happy to help! Thanks.