randyb_boxster

Here's the car -

2011 Cayman S
- Pagid Orange Pads F&R
- Motul RBF600 full flush out
- Stock 18 tires and wheels
- Only four track days: one local airport, 3 Hallett Oklahoma - total 390 track miles
- Advanced driver

My rear calipers are turning from bright porsche red to maroon-brown. Is this normal? My previous car, Boxster S, had no issues with color changing calipers. Before I call Porsche and ask what the heck?, I thought I'd ask you guys....anybody seen this before? In the rears!?!

Also, changed out pads - fronts were at 50% and rears were closer to 30% - is there supposed to be that much rear bias? Fronts look fine.

Want to make sure I am not working towards a complete roast toasty of the rear calipers.

rubber_ducky

It happens quite often unfortunately. The belief is that PSM, which is never fully disengaged (even with the center console switch turned off), is the cause. Some have added rear brake ducts and Ti brake pad shims to help keep the calipers cooler.

randyb_boxster

I didn't think about PSM. I was driving in sport mode so it was on. I hate to turn it all the way off. My main fear is having a caliper piston seal fail (or melt). Color can be fixed before resale.

rubber_ducky

I'm not an advanced driver and my calipers are still a bright red. But I've seen this often enough to have picked up a set of 996TT rear brake ducts. They need to be cut down to fit.

Ti shims will help to keep the pistons somewhat cooler, prolonging the life of the seals some.

randyb_boxster

More research has revealed that the real culprit for my braking may be the ABD - automatic brake differential - which according to Porsche "When the drive wheels begin to spin, the automatic brake differential function (ABD) initially brakes the individual wheel with the higher level of slip. If both wheels spin, ASR intervenes in a fraction of a second." ABD appears to act independently of PSM.

That means the little monkey in my trunk (the PSM/ABD computer) is riding the brakes everywhere the car may be rotating on track...in fact, a couple of the latest model drivers have 1) reflashed to delay or eliminate ABD and/or 2) added brake ducts for the rears. I am riding around the track at full throttle and the monkey is mashing his brake pedal to the floor!!!

This is most alarming. I will work to become more aware of the conditions of the ABD this weekend. I am also fashioning some cooling ducts similar to the fronts for the rears...temporary until I can find some 996TT ducts on the cheap.

rubber_ducky

^^^I'd heard this as well^^^

Sounds like an e-diff of sorts. Allegedly LSD equipped cars don't suffer from this issue as much. Perhaps ABD is dialed back on those cars?

randyb_boxster

I think the other thing I am doing is putting OEM pads on the back. Logic: lower friction = less heat. Cheaper pad, too.

Driver8

I would not recommend running Pagids on the front and stock pads on the rear. The difference in pad make up is too different. You will be asking the fronts to do even more work then the rears

randyb_boxster

At Texas World today. My self engineered cooling ducts seem to be working - at least to keep pedal from getting mushy. Agree with last comment and may try Pagid's new Sport pad for rear.

A couple of post-2009 cayman s's here at this track day have darkened rear calipers.

randyb_boxster

Porsche says its PSM and my problem. Thanks!