Porsche Cayman S - Intermittent Problem with Brakes

Honest John Back Room » Technical matters
View Threaded
Wed 16 Mar 2011 08:00
Porsche Cayman S - Intermittent Problem with Brakes - amp33385

I have a Cayman S which basically has almost zero braking maybe one time in 20. On the other occasions it brakes ok.
When it doesn't work properly the pedal stays firm rather than going to the floor but just doesn't slow the car down properly
The front discs & pads were approaching the end of their life but there was no odd braking noises / other signs of a fundamental problem
I asked the garage to check it out & change the discs & pads.

Their assessment is that there is no obvious fault anywhere in the braking system, having checked everything over (fluid fine, no sign of leaks, master cylinder ok...)

They can't replicate the fault but having changed the discs & pads say the brakes are miles better in general use
Has anyone had a similar intermittent problem or have any ideas what the problem might be - I am surprised that just changing discs & pads has solved this. I don't have any idea what to ask them to do next / how to isolate the problem

Reply | Report as offensive | Link
Wed 16 Mar 2011 09:08
Porsche Cayman S - Intermittent Problem with Brakes - Peter D

First thing I would do is change the one way vacuum valve at the servo. If this valve fails it can cause a loss of vacuum and the pedal will be firm and ineffective. Just sit in the drive with the engine off and use the pedal 10 times and it will then feel like your fault. Also check the brake operation before starting the cat after it has stood all night, or day. The brake should operate properly at least 2/3 times before it hardens. Regards Peter

Reply | Report as offensive | Link
Tue 22 Oct 2019 16:40
Porsche Cayman S - Intermittent Problem with Brakes - Matthew Tinnelly

Sorry to drag this up, but did you get it sorted? I have a similar problem with my Cayman S. Discs and pads were done recently so no problem there. The Vacuum pump has been changed which has improved things, however for me I can still push the pedal to the stop and intermittently get very gradual braking. This often occurs when creeping forward, less than 5mph.

Changing the vacuum pump improved braking through the range and was clearly on the way out, but I still have this intermittent fault.

Reply | Report as offensive | Link

Looking for a garage you can trust? Honest John's Good Garage Guide has thousands of reader recommended garages, plus how-to guides and tips on servicing.

The Good Garage Guide