Brake problem, I think....

I think I have a problem and looking for a little help. ( 2006 Cayman S tiptronic) I'll start with the symptom. While seated in the car (running and in park) if you push and hold the brake pedal it slowly fades to a point just off the floor. If you push the pedal again it is real soft and if you pump the pedal a few times the pedal gets hard, but if you hold again it fades to a point just off the floor again. With the car in drive you don't really notice the pedal fade, and if the car is off you only notice a little fade. Ok, here is the history. I have had the car for about 5 months and have taken it to 5 DE events. After the third event I flushed the brake system, by the invite a friend over then pump and bleed method with just regular auto parts DOT4. At this point I was not having any problems but probably not going fast enough or experienced enough to know. For the forth event I put on a set of Nitton NT01's and thought the brakes were a little weak at the end of the day. For the fifth event I flushed the brakes again, but this time with a power bleeder and Moutal 600, and put a set of YellowStuff pads on the front (rear did not come in time). I did a short bed in and then took it to the track. This time the brakes were real weak but I figured it is probably because the pads were not bed in enough. Today I put about 100 miles on a small 1.1mile track so the brakes should be bed in now. At the end of the longest straight I would have to pump the pedal a few times to slow down and even with the greatest of effort could not get the ABS to kick in. When I had to brake a few time in a row for a series of close turns the pedal would feel better. Also when the "stability" system needed to kick in the braking force was strong. At this point I don't remember what the car is supposed to feel like, so someone please jump in the car and do the same as I did and let me know what happens. I would appreciate any advice, help, comments.

DANGER WILL ROBINSON!! That certainly doesn't sound like normal brake behavior (nor does your pedal sinking to the floor when in Park). I'm no expert, but it sounds like you probably have air in the brake lines somewhere. Did you bleed your lines starting with right rear-left rear-right front-left front (outside nipples first)? If you are using a power bleeder, it is very easy to introduce air into the system if you let the fluid get too low in the resevoir while flushing or bleeding the system (been there, done that). I think you need to carefully reflush the system as above, taking care not to ever let the brake fluid fall below the low mark during ther process - if that doesn't help, then you probably should take it to the dealer. My 2 cents . . .

Thanks for the input. Both times we were very carefu to never let the fluid level get low and we did follow the bleeding sequence you mentioned. Both times we flushed a full pint of fluid through the system and never saw any air bubbles. I'm thinking of taken it to the dealer but want to make sure i have not missed something simple so I don't feel like an idiot when they tell me " no thats normal" or something similar

I had a problem like that in my 94 3.6 turbo. I ended up having to replace the brake accumulator and one other part which I can't remember. I believe I read somewhere that a similar system exists on the Cayman .

A sinking pedal is very bad, very dangerous. Could be a leaking master cylinder, or a leaking accumulator. Either way, get that thing to the dealer right away. Don't play Russian, er - um, I mean German Roulette with your brakes.

Have it towed to a service place ASAP!!! Do not drive the car.

Once again, thanks for the help everyone. I have booked a service date for this Friday and will post the results.

If brakes were proeprly bled, it certainly sounds like a bad master cylinder. spm, cpa

Kermit, I've been doing some research on this since I have some similar issues with my car. Here is an exerpt from an article on pelican: Checking the Brake Booster for Correct Functioning Before disassembly, it is a good idea to check the booster to ensure that it functions properly, so that it can be corrected at the same time as the master cylinder if it is defective. Here is how to make sure it works right: 1. With the engine stopped, depress and release the brake pedal several times to remove any vacuum retained in the booster. 2. Hold down the brake pedal with medium effort, and start the engine. 3. If the brake booster is functioning properly, the brake pedal will give slightly underfoot as the booster takes effect. I've found similar information elsewhere on the web. So it appears that at least part of what you are experiencing is normal. It could be that you are seeing it magnified somewhat due to a problem such as additional bleeding needed after the track use. Also, I've read that if the pedal holds steady at step 2 before starting the engine, that indicates the master cylinder is holding pressure ok. I think the dealer visit is still a good idea, but it might not be too major of a problem. Dave

You have a bad master cylinder

Interesting. After having posted a reply on this issue I now find myself with the same issue. I put in a set of new rear pads and bled the brakes Thursday night with a power bleeder. Checked the brake pedal afterwards expecting no drama. Surprise, I had a soft pedal. No issue with pumping air into the system. I'm anal about doing one corner at a time and then filling the master cylinder reservoir. I screwed it up once about 5 years ago and still remember the mess. So I went through the process again. At the end there was no air at any corner with the soft pedal still present. A quick call to my local dealer and they told me to bring it in and they would work me in. At the dealer they hooked up their power bleeding system and went through the process. At the end I still had a soft/fading pedal. At that point the tech decided to go out to the lot and check a new Cayman S for pedal feel. He found that the new car on the lot had a firm pedal with the engine off. Leaving the foot on the pedal and starting the car the pedal slowly went down about halfway and stopped. At that point I decided to take it and drive it a bit to see if any pattern showed up. What I found was a fast stab at the brakes would activate ABS with no issue stopping. Stopped and pressing the pedal I could get it almost to the floor. There was resistance and didn't have the feel of compressing air bubbles in the lines. Just not confidence inspiring. And this is on the third bleeding session. So I took it home and did it again for the fourth time. In the end the same semi soft feeling on the pedal. I've burned through 5 bottles of Motul RBF600 not counting what the dealer ran through the system. Here is where it ends for the night: Key off the pedal is hard and firm. Start the car with my foot still holding pressure and the pedal slowly sinks. Release the pressure, wait and put pressure on the pedal again and I get a faster sinking to the floor with the pedal nearly reaching the floor if I keep pressure on the pedal. I'm going back to the dealer again tomorrow. So no Mid-Ohio this week. I'll update when I get this solved. If you're tired from reading this I'm worn out from doing the process.

Did anyone think of doing a search? Excessive brake pedal travel. those discussions and several other threads conclude it's not: -poorly bled brakes -air in the system -the brake fluid -the brake pads -the brake hoses -the master cylinder and it's not acknowledged by PCNA

Thanks Dan. I think One note. I had run 3 days at Putnam Park with no brake issues previous to this.

Possibly a red herring since I haven't been into this one yet but I think these calipers are similar to my old 944S2 in having two bleeders per caliper. After one fluid change years back I ended up with a soft pedal though not to this degree. Ended up curing it by bleeding at both points on each caliper.

In the old days bad MC would have been my answer. But it seems I've read that it has something to do with the ABS.

Alan - How did you compress the rear pistons? You probably did it correctly since you stated you've done rear brakes before, but... spm cpa

Spmca, I use a pair of channel locks and grip the backing plate in the center of the pad and lightly pull the pad to the outside. I didn't need to move the pad much as I was replacing pads which only had about a 1000 miles on them, street. On one side I was able to just wiggle the pad out. Good news, I was able to make one day at Mid-Ohio. Bad news, the brake pedal went to the floor at the end of the back straight on lap 3. I gave up packed up and came home. Back to the dealer tomorrow. A friend was there with the same setup that I was running and he had zero problems. With the engine off the pedal is rock hard. STLPCA - I have read the articles in the past and plan to refresh myself on them prior to visiting the dealer tomorrow. Thanks for posting the link. I'm beginning to regret passing on a very nice low miles '08' CPO C2S.

Update I dropped the car off today for the soft brake pedal. The first thing they did was to explain that I owed them for 2 brake bleeds since I had it done by them twice already. The mechanic insisted that I had let air into the system. I'm sure I didn't but that's his stance. So I asked them why I should be charged for the second one? It would appear that the job was done improperly the first time. While they pondered the question I hit the brake pedal hard as if in an emergency stop and the pedal went to the floor. I looked at the mechanic and asked if this was good. No response. When they call me tomorrow this car will have had a total of 6 brake flushes in 6 days. If it's the same when I pick it up I'll put it up for sale. My string of 21 Porsches will come to an end.

Alan: Good luck with this. Sure sounds like a master cyl. Hope they take car of you. Sounds like you may have a defective dealer. Keep us posted. For the record, I just did first DE with my '06 CS. Bled brakes, installed Pagid Yellows and a set of Boxster S wheels with NT-01s, Taught at a Road America charity event for March of Dimes and gave many demo rides and laps in student cars, got home and put everything back to stock. No problems at all. This is some sort of anomoly and the dealer should take care of you. Because I didn't replace pads in the exact same positions as before (probably), They need bedding in again to match the surfaces of the rotors to the surfaces of the pads. Both are still pretty flat, but it takes a little time for them to normalize and I'm avoiding hard stops on them for a while. Everything works...Pedal is hard and feels good, Just a little softish braking from the unmatched pads. This is far different from a sinking pedal. Whatever happens, Don't give up on the car...maybe the dealer, but not the car. Good luck! :cheers:

I know what you mean about pads in the wrong place. I learned from Larry Schumacher's crew chief years ago how to easily mark the pads. He used 1 notch on the LF outer pad, 2 notches on the LF inner pad, 3 notches on the RF inner pad and no notches on the RF outer pad. Follow the same procedure for the rears. Pretty easy to do. Lay the pads down and put a notch on the top of backing plate with saw blade or light tap with a small chisel.

Or, just mark it with a dremel tool..RF, LF...you know.

Or just mark them with chalk when you take them out: LO LI RO RI (there's no confusion between F & R). Works for me. Alan (& six) - if your issue is the same as mine, it is not a master cylinder. Replacing the MC was the first thing done by my dealer. Good luck & keep us posted.

All good ideas. I think I prefer marking them permanently but just forgot this time. I'll get my track pads out and mark them tonight so it doesn't happen again. An etcher or Dremel sounds like a good idea. That way I won't forget my code next spring. Letters are always self-explanitory. Good point that front and rear pads are obvious. This was my first DE with this car...so much new stuff to absorb. Once I get my system down, it'll be easy to get everything right every time. Luckily this first run was just 4 short sessions in cold weather. Not a lot of rotor wear. I went for a test drive on the street setup last night and brakes were silent and good. The braking was just not as firm as it would have been had I marked the pad positions before I took them off. A little bedding in and they'll be fine.

A file works well to add the notches, like Alan describes. Our guys mark, 1,2,3,4 notches from left to right (picture yourself in the driver's seat, reading left to right). It'll be interesting to see what the dealer finds as the root cause. Hopefully they'll sort it soon.

The service manager called today and they are replacing the master cylinder and the brake boost. They found a bit of brake fluid under the master cylinder. Hopefully this will make an improvement.