L76

Hi Guys,

Track day coming up. Checking pads and rotors. Anyone know the min thickness for front and rear rotors before they need to be replaced? 981 Cayman GTS. I track the car for DE days 3-4 times a year. Any recommendations on rotors if I replace them? Pads?

cheers,
L76

Clark-ApexPerformance

For liability reasons none of the manufacturers I deal with post any minimum thickness. ( IE Giro Disc, AP or PFC) The rotors usually crack out before they become too thin to run.

Denny Swift

I’m pretty sure the minimum thickness is stamped into all disks by law. I could be wrong…

thecajunboy

This is from the PCA website. A bit dated, but I imagine that it hasn't changed.

All Porsche rotors have the Min. thickness written on them. The part number and thickness is written in a dot matrix on the hub. They do this on each rotor so there is no question as to what it is. The Boxster S front rotors have a min. thickness of 26mm and the rears are 13mm. Scott Slauson - PCA WebSite - 1/17/2005

Kitc2246

I use Sebro slotted and Pagid RSL29s from FCPEuro with their Lifetime Warranty but DE 4-6 times a year. I leave the pads on year long, just change back to the 20s at the end of the DE season. On the third set of fronts but same rear. Costs $50 to mail back the old ones and get credit. New fronts are 28mm and rears are 20m with 2mm wear or 26 and 18 min for my 2013 Boxster S. Specs are in the rotor/disc details of most websites selling rotors and min stamped on the rotor The rule of thumb is feeling a significant lip on the edge. From my early DE experience with drilled rotors the cracks from the holes get too long (5-6mm), join or to the edge before they get too thin. Most people switch to a Sebro slotted or equivalent which are much less proned to crack. My son and I edge cracked both fronts when we back to backed the car at VIR. The slotted transfer more heat to the fluid, so a high end track brake fluid is needed. I use Motul 660. PCA got really strict with pad thickness last year after a few incidents. Minimum pad thickness is the width of the backing plate. Had to drive home and change pads and back after two days of a three day event. Now I always carry a new or used set that will pass tech.

If not already recommend brake caliper studs to eliminate the risk of damaging aluminum threads with the steel brake caliper bolts.

2013 Boxster S PDK, SC, PASM, PTV, PSE added third radiator and adjustable LCAs

ncster

Kitc pretty much answered your questions.

For the 981, front rotors are 28mm new, 26mm minimum thickness. Rear rotors are 20mm new, 18mm minimum thickness. For 3-4 DE events a year, would recommend Sebro slotted rotors.
I personally really liked the Ferodo DS3.12 pads (fantastic bite, no fade at all during 20 minute session, quiter than OEM pads on the street). However, currently facing some issues with the pads (I have a thread about it), so I might switch over to Pagid RSL29s from FCPEuro.

toma nova

For 3-4 days a year, consider staying with OE (Sebro rotors and Texstar pads). Good performance, decent life, lots of dust. Definitely change the DOT4 fluid more often or go to Motul 600 or 660 but that is only good for 6 months.

ncster

I would disagree on the brake fluid. If you're taking the car to the track at all, you must use proper high temperature brake fluid. The standard DOT4 fluid will boil and leave you with no brakes. I've only been tracking for a year but see it happen almost every event.
Motul 600/660 and similar can easily last a whole year with 3-4 track days.

L76

I have been using Motul 600 to-date, but the last time I tracked the car the third run out my brake pedal felt a little spongy. I'm on stock Porsche rotors and pads (I drive the car regularly so have never "stepped up" to race rotors/pads. 981 GTS. Think they are the the same brakes (pads/rotors) as on the 981 S (?). I do PCA DE days 3-4 times a year in the car. Never race it. I am thinking of running Castrol SRF this time. Thoughts? I was gonna measure/inspect the rotors and pads (and only replace if necessary). I like to change only one variable at a time so I know the true impact of the change. BUT - if I am forced to change rotors and pads...

cheers,
L76

slivel

Your question about checking rotors and pads: On pads, I always changed my pads when they had less than 50% thickness. Reason was that the reduced pad material transfers more heat into the calipers and can also contribute to a long or soft pedal, particularly if you have any warping (runout) on the rotor.

maschinetheist

Castrol SRF is good, I've ran it the entire season this past year.

As for pads, like it's been said by slivel - change if your pad material is the same thickness as backing plate. Less pad material equals less heat that it can take on.

Kitc2246

A firm pedal with reduced braking is fade when the pads are too hot. Boiling the fluid creates a soft pedal or worse to the floor. Possible, but doubt you boiled new Motul 600. If they where OEM pads suspect they were too hot. Buy a cheap brake fluid moisture detector from Amazon. Previously DEed an 09 Boxster PDK Sport/Sport+ using OEM manufacturer drilled rotors and various track pads using ATE 200. Never any brake issues. Started DEing my current 2013 Boxster S PDK Mar 2020. I had added the third radiator, adjustable LCAs, Sebro slotted and track pads. Boiled the ATE 200 the second session. Had it flushed and replaced with Motul 660. As previously mentioned IMO the Sebro slotted add more heat to the fluid than drilled. Obviously more HP and speed with the S. PCA Potomac requires DOT 4 be changed every 3 months and racing brake fluid every six. If you check Motul 660 has a higher dry temp while SRF has a higher wet temp. For my purposes I see no need to pay the premium for SRF especially changing every six months. If properly bedded my Pagid RSL29s normally do not squeak on the street. I don't have the front pad dampers.