We have a 2015 Cayman S - owned a few years now. When we first got the car, it had a super firm brake pedal - like a sports car should. I did a track day the first summer we had it, and the brakes were amazing. Then talked my wife into doing the Porsche Club "Lady's Day" track day. She loved it and even commented that the brakes were surprisingly strong. She did say that the instructor noticed some light smoke coming off the rear brakes at one point during the day. I chalked it up to end of life pads.

The day after her track day, I drove to the car wash and the pedal was mushy. Brakes still worked but required a pretty firm push to get really good braking. I thought she smoked the brake fluid. Since the rotors were grooved and the pads were done, I replaced the pads with the FCP replacement rotors and went with some Hawk street / light track pads (forget the exact ones). Then took to an Indy shop for a good flush and high temp fluid. Got the car back, same issue. Told them I wasn't happy and they tried again. Same thing. They told me that it "felt fine" and suggested it was the (in their opinion) "crappy" Hawk pads.

I should note here that I have road raced motorcycles / ridden dirt bikes / worked on my own cars for years - mushy pedal / levers have always meant a fluid issue and had nothing to do with pads / rotors.

Willing to play along, I replaced the Hawks with EBC Reds. Still same issue.

In frustration of not having that great pedal feel, I took it to my local Porsche dealership. Asked them to check the whole system for leaks (I never found anything in my inspections), make sure they flushed the ABS, and do a good flush. Got it back from them and it was the same. Service guy said it felt "normal" to him and the service tech.

Fine. Did another track day and again, the brakes do work fine, they just don't give that great pedal feedback the car had when we first got it.

Decided to add some FVD stainless steel brake lines to see if maybe I had a rubber hose expanding under pressure that wouldn't be easily seen during inspection. Back to a different Indy shop to have them installed and bled for the 4th time.

Admittedly (and expectedly) the brake pedal is a little better - however, it's just not the same as it used to be - nice and firm and really easy to get hard on the brakes when required.

Frustrated that the amazing pedal feel hasn't returned. For reference, the car has about 62,000 miles on it ... everyone I take it to says "it's fine" but I don't agree.

Any thoughts? Anything else to check?

Sorry for the long post, but wanted to include all information. Thanks in advance.

 

I've been in your situation and understand exactly what you are describing, right down to technicians telling me, "Everything feels normal..." It's really frustrating.

My first thought is that something may be awry with the internals of your master cylinder. I have no idea how one tests the master cylinder on these cars, but given that you've basically rebuilt the system from the master cylinder out, you might want to look there.

Another cause of mushy pedal would be excessive rotor runout on one corner, but you'd see evidence of that on the offending rotor/pads. Plus, I don't think that's very likely given that you replaced rotors/pads after the problem surfaced and the issue persisted.

 

Can you figure out what pads were on it originally? You probably want to be looking at semi-metallic pads not ceramic. I'm honestly not sure how big of a difference it is but it's definitely something.

 

The pads and rotors I replaced appeared to be the original / stock rotors and pads (car had around 55k on it when we bought it) ... Again, I've never ran across a brake pad making the pedal feel firmer - you can tell just sitting still in the driveway that it's "mushier" than it used to be. So frustrating ....

 

Yeah, this is definitely a weird one. I guess it could be the MC, although if one of the pistons were leaking I'd expect a low pedal, and I hate to suggest throwing more parts at it. Is the pedal lower than before, or can you get the pedal to sink if you hold it or slowly press it?

If you can buy/borrow a brake pressure gauge I guess you could check pressure at each wheel, see if something weird is going on with one of the circuits which would indicate an MC problem. You could also try pulling ABS codes to see if anything's going on with the pump module, though I'm pretty sure that's just passively inline when ABS isn't engaged so it's a long shot.

Some performance pads can feel pretty crappy until they get hot, but it doesn't sound like you're using race pads, and again I hate to propose throwing more parts at it like going back to OEM pads and rotors.

No brilliant ideas beyond those, I'm afraid.

 

I don't see how it could cause a 'mushy' feel, unless it's related to heating up the pads more than usual, but you might have a look at the brake pedal bushings. On some of the 981s they have been found to bind up and keep the brakes from releasing properly under some conditions. Sporadic cruise-control dropouts are one symptom of this, as is the usual hot-brake smell when you pull into your garage.

 

Sounds to me like you have a small bubble of air somewhere. Seems unusual that 2 flushes didn't get it out, but sometimes it takes more.

 

Yeah, I was assuming they bled it right (and did the ABS bleed procedure right) but could still be some air in there somewhere, I guess.

 

Agreed, keep coming back to air somewhere, but it's been bled 4 times now, by three different shops (well over $1,000 in fluid / bleeding now) ... I would think one of them would get it right.

The pedal does "travel" more than before, which is giving it that mushy feeling ... before it was crisp and had good bite right off the top of the travel.

 

AFAIR, my cayman has always been like that. The pedal is super soft, and the first 30% has ‘no’ resistance - resting my foot on the pedal, with zero pedal effort, gets it to like 30%. I think my previous cayman was the same/similar.

The car gets flushed annually and bled every ~4 track days. The pedal is soft and deep with new or old rotor/pads. With new rotors and pads, there is more inital bite, for a track day or so, but the pedal is the same. It’s got SS lines. I’ve even, sceptically, put in a GT3 MC out of desperation (I was quite convinced it wouldn’t do anything).

I’ve run out of ideas on what to do. At this point I think it’s just a matter of how these cars are with their MC/caliper sizing. I recently drove a student’s (brand new) 911T, and the brake pedal was perfect. I suppose if we replicate the entire brake system, we could get the same feel. But at that point, might as well get a BBK.

BTW, there’s an ABS bleeding procedure or something under PIWIS. For those with problems, it’s probably best to try bleeding it using that.

 

Also, FWIW, every cayman I’ve driven feels like that. All other cayman drivers I know report the same thing (can’t remember if that includes GT4s). The only exception is when PCCBs are on the car.

 

I drove a 718 GT4 and a 2023 911T and both have firm, perfect brakes with almost zero pedal travel. Even my 2015 Boxster GTS is much firmer without pedal travel than my 2022 CGTS4.0

 

I don't know about the 981, but on the 987 a solid upgrade is to install the GT3 master cylinder. It has a larger bore so it provides a firmer, shorter throw pedal. I was pretty disappointed with the stock brakes on my 2010 CS (long, soft pedal) until I did this.

Maybe that's an option on the 981 as well? I know the PCCB cars typically get a the larger bore MC and I'm convinced that's a big part of the difference in feel with those cars.

That doesn't sound like OPs problem, though, since he saw a step change in performance.