Hello,

I have Cayman S 2007. Just bought it in mid Feb. of this year with 11,000 miles.
I modified the suspension, slotted brakes, Pagid Yellow pads, etc…
I bought it mostly to use on tracks from VIR to W.Glen, East Cost.
It happened at the Watkins Glen when I pit after a session and the car cooled off slightly. I seat in the car with ignition off and pressed the brake pedal. To my surprise the pedal easily traveled to the floor. I started pumping the pedal and it became firm again. It happened that Spencer *** from Farmbacher Loles was at the track with a client and he as a generous man bled the whole systems, inner and outer. He also made a suggestion that it is an ABS failure and I have to change it to the Racing Unit which is very costly. Now I know that the unit cost $10,675 without installation.
Back to the Glen.
The pedal was firm again as it suppose to be after the bleeding. I went to another session and everything was okay during the run. But after I pit in I turned the ignition off, wait a few minutes, pressed the brake pedal and to my surprise it surrenders again.
After pumping it became firm again. I decided not to do anything this time and went to the track for the next session an hour later. I drive hard as usual but with alert senses towards the brakes. Everything was working perfect, however after 10-12 minutes I started feeling that after the long straight, where I reached 130+ mph, the brake pedal started feeling like going some more distance then usual. After some less speed on shorter straights but still hard braking I felt the same and quit driving.
With Spencer we went to the on of Chicago Porsche dealership which was with their team of GTs on the track at the time, they immediately connected the computer, checked the system but there was no any troubles found. By the way, ABS or PSM lights were never on. I drove with PSM “on” since I never driven Porsches yet and as I said it was my only 3rd day with this car on track.
However I started HPDE events in May last year and had 39 of them by the December of the last year. I drove BMW M3 2006 then which was a great car with little troubles, but the Cayman is superior, I like it, however brings me a huge headache.
After that Spencer bled the whole system again and I just drove 100 yards, stopped the car switched the ignition off and the pedal traveled to the floor again.
It was possible to pump the pedal to the firm point again.
There was another man on the track who made the suggestion that it is the main, master, cylinder problem.
I had nothing to do but abort the track sessions and go 270 miles back to New York, where I lived. There was no problem with braking on the high way; I even tried some on speed of 90 mph.
The main or master cylinder was changed in a couple of days with full bleeding process.
I went to 2 days even at Shenandoah. Everything was perfect. I get use to the car more and more and switched the PSM off.
I drive in advanced groups at all the tracks and drive hard on the car braking hard, and short and some mechanics thought that because of that the overheating happened.
I personally wasn’t agreeing with them feeling that there is some other issue.
I also have air scoops from GT3 and use only highest boiling point fluids.
After the Shenandoah I immediately drove to Thunderbolt and next morning was able to drive 2 sessions without problems with PSM on. There were only 2 run groups, so 30 min on track, 30 min off. Quite a stress to the machine, although the weather was not hot. After the third session I was sitting in the cooling off car and pressed the brake pedal and it was traveling to the floor again. After pumping it became hard and then surrendered to the floor under the foot pressure.
I started the 4th session caution and turn off the PSM, but quit very soon feeling that the braking pedal is started surrendering slightly again after hard braking.

Next the Titanium Shims were added to my calipers to deal with excessive heat, the brake lines were bled thoroughly again with Motul RBF 600.

I went to the Glen and on the third sessions everything was back again.
I quit and went home.
By the way, though the braking pedal surrenders to the floor under pressure when the car not moving with running and “off” motor, the regular driving is absolutely okay and on track the brakes work perfect. The braking is really good, it is just the distance of pedal travel increases; I never lost the brakes, but I read an article in Porsche Forum that on guy during the racing lost the brakes completely on the Bus Stop at the Glen on his Cayman S. There are also some posted articles about similar to mine troubles with Cayman, but no solution mentioned found, only suggestions, but I already read tons of them, I need the solution. I posted this letter in a few different webs and received only suggestions which a school boy knows about.

I spent days reading diff. articles about such problems with Caymans and what could be the cause and now I’m looking for the people who already dealt with it and want to know the result.

There are a few suggestions that I could follow, I picked them up from what I read.

1. Change to expensive Bosch ABS 4 Racing System.
2. To find some other less expensive Racing aftermarket ABS System.
3. Find the way to cool down the fluid before it gets to the original ABS.
4. To trade the car in for BMW M3 2006 which I had before and loved it.

So anybody, who already went through such problem and solve it successfully in any of the first 3 solutions, please share the experience. Help me and others who are already desperate and those who are going to get in to the troubles sooner or later in the future.

Or is it something different and not ABS at all?

Thank you,
Lev Uretsky
Brooklyn, NY.

 

Lev,

Sorry to hear about your troubles. You might want to try asking the folks over at the Cayman Club forums and the Cayman list here. They may have better answers for you.

Good luck,
Chad

 

There is alot of discussion concerning this very issue on the Planet-Porsche AKA Cayman Club board. Do a search in the "modifications" as well as the "competition" forums. What is interesting is that the problem isn't universal. Myself and several other Cayman owners run with suspension mods along with R compounds or Hoosiers and have yet to encounter the problem. I have about 6,500 track miles on my car, including at The Glen, running with advanced groups and have fortunately never had any brake problems. FWIW I use PFC 01/97s, PFC front rotors, SRF fluid, GT3 brake ducts and have removed the front debris shields.

Just out of curiousity, what size tires are you running F&R, the ABS issue seems to crop up with F&R tire size differential >5% rotating diameter.

 

I can add a bit of insight since I believe i have 10,000 track miles spread among 2 caymans. What you are experiancing is excessive heat from overuse of the ABS system. Air in the abs pump is hard to remove. It is sometimes hard to feel the slight pulsing of the abs as it does its magic, the combination of the psm working keeps the brake temps very high as it engages them to keep the car steady. A short term solution would be black pads with srf fluid and turn off the psm.

BTW did you ever also feel the clutch stay on the floor and not return after a really good run?

 

The person who had the braking problem at the bus stop during the club race was Joel Furey. I had a talk with him at Mosport about it, and he had the same ABS failure that I had in my boxster at a Summit Point race. Basically, the ABS pump failed internally and brake fluid was shooting out of the pump into the front trunk rather than circulating through the brake lines. This is obviously not the problem you are having.

I was having similar problems this last weekend at the Glen club race in my Boxster, and my guess is that I overheated the fluid and it needs to be fully changed. I'm planning to have the whole system completely flushed and see if that helps.

Also, FWIW, I find that I can also fairly easily push the brakes to the floor when the power is off. A few pumps makes it firm again. I've never found that to have any real correlation to the actual braking performance when the power is on.

I think Alex has the right idea about air in the ABS pump.

 

I have more than 15000 track miles on Cayman S and have yet encounter this problem, but it happen to a lot of folks like morefun said, you are not alone.

The latest suggestion is to bleed the brake with engine running.

 

All cars have some issues with brake heat, I have in tha past overheated the fluid and the pedal gets spongy, as well as the clutch not returning from the floor. Thats when you know you really used em

make sure you bleed the clutch as well since it is connected. I cant seem to find a reason to leave the car running but it might be worth a try

 

At the minimum I'd switch immediately to Castrol SRF. It's worth a try....

 

Go to this website they are Cayman centric.

http://www.planetporsche.net/

 

I agree with Brian explanation of your problem. Seems more temperature related (fluid, pads) than a real ABS failure. The Cayman would be perfecto with bigger brakes (or 300lbs less)

A real ABS failure is NO brake power at all! Happened to Joel's (now my car) and when you get out of shape wildly (Spin, 180, 360..) and the PSM might came back on and don't allow any braking power.

Bleed the system, use the right fluid and good endurance pads (more linear friction with high temps) and that's the best you can do with the OEM system (Ah, also stay off the brakes as much as you can for proper cooling...i.e. don't drag your foot with mild pressure over the brake pedal)

 

Spencer has done a couple of things to my car
- Endurance yellow pads
- Cutting the YAW cable on the PSM
- Increasing Air flow to the brakes.

I think the next step is change the ABS unit, most of the 997 Koni teams have experienced this same issue - they all ended up using the Bosch or similar units.

I spoke to the cayman cup guys in france and they have done all of the above but they also use a less aggressive tire - I belive that they use the DOT corsa type tires.

 

FWIW, I was not a big fan of the yellow pads for a racing situation. There is FAR less bite with the yellow pads than there is with the blacks. Take a look at Pagid's friction chart to see how dramatic the difference is.

 

Ramblings of a non expurt.

Air in the ABS should trigger a light and the problem will be felt uniformly not once in a while.

I would be inclined to check that you are not just seeing the fluid cool and contract during off times. Normally the fluid heats and expands back into the reservoir during use and then back in the system while at rest and cooling off. If something was keeping the brake pedal slightly depressed the fluid will not be able to return to the system and you will get a long pedal as you pump the fluid back into the system.
To check, Note the cold fluid level before you go out. Note the hot fluid level when you come back in. Note the fluid level before you go out the next time before touching anything or starting the car. It should be higher when you come in hot and return to close to the normal cool level on its own. If it does not you will get a 1 or 2 stroke long pedal If it does not does the pump or two to get a firm pedal drop the level to the cold level? If so the MC piston could be being held slightly in which closes of the equalizer hole that lets fluid move from the MC to the reservoir.

 

PSM is on. You're overheating the brakes. Turn off PSM and most likely the issue will go away. If it was an ABS/PSM fault you would get a fault lamp.

 

My sentiments are with Bill. Add to this the following:

Out of spec diameter difference between front and rear tires (rolling diameter difference too great) freaks out the traction control and PSM. Brakes get used a lot.

PSM and or Traction control on and overdriving the car will cause lots of brake action. rotors turn blue, pads wear fast and pedal goes soft.

Are any of those possible in your case?

Regards,