Cayman S 981 - Judder felt under brake pedal when braking - Page 1 - Boxster/Cayman - PistonHeads UK

Hi all, Does anyone else experience judder under braking, almost feels like that pulsing you feel under ABS. I've only had my car for week (July 2014/14 Plate). I also notice very small vibrations through the steering wheel also when braking, and the braking does not have to e excessive to experience it. I think I may have a warped disc or something if this is not normal characteristics of the car J.

It may just be pad deposits on the discs. Get the car up to high speed and stand on the brakes hard to bring the speed down to nearly, but NOT a stand still. Repeat this procedure about three times and if that doesn't work then you have either warped or rusty discs.

Trev450 said: It may just be pad deposits on the discs. Get the car up to high speed and stand on the brakes hard to bring the speed down to nearly, but NOT a stand still. Repeat this procedure about three times and if that doesn't work then you have either warped or rusty discs. this imo

Thanks guys, I did try that on the weekend with no result. It's gone into OPC today for them to take a look. I will report back when I get an update from them.

All sorted - just heard from the OPC, they have independently said it's warped discs. They are replacing the discs and pads tomorrow, all covered under warranty

Jonny08 said: All sorted - just heard from the OPC, they have independently said it's warped discs. They are replacing the discs and pads tomorrow, all covered under warranty excellent result - sorry if a noddy question, but how is this covered under warranty? surely your discs warpping are wear and tear on 14 plate car? or has it done very little mileage?

Trotmant said: Jonny08 said: All sorted - just heard from the OPC, they have independently said it's warped discs. They are replacing the discs and pads tomorrow, all covered under warranty excellent result - sorry if a noddy question, but how is this covered under warranty? surely your discs warpping are wear and tear on 14 plate car? or has it done very little mileage? More than likely because the OP has only had the car a week.

Trotmant said: excellent result - sorry if a noddy question, but how is this covered under warranty? surely your discs warpping are wear and tear on 14 plate car? or has it done very little mileage? The car has done 10K miles, which personally I do not think would be enough to require a new discs. I didn't have to challenge them at all, they just said "We've drove the car, we also experience the behaviour you have described, and have identified that there is warping of the discs. We will need to replace these and the pads" I was expecting them to try and bill me for the pads, but no - they said the pads requiring replacement is collateral from the discs warping. Either way, I bought and picked the car up last Monday, it really should have been picked up in PDI checks. I had no plan on footing the bill if there was one anyways :-) Also worth noting, I bought the car from a different OPC to where I've dropped it off for the work. (OPC I bought it from is 2 and a half hours away!) My treatment from all Porsche Centre's has been brilliant, great car, great experience so far :-)

Glad to hear you have an excellent outcome regarding the brakes. Nagging at the back of my mind would be, "If someone's driven the car badly enough to damage the brakes.....". Although if it's a PDK the computer can make a fine job of protecting the driveline from idiot drivers.

Just FYI - there is no such thing as warped ventilated discs. Really. Think about it. What temperatures do you think will warp a metal disc cast in a foundry? Unless the previous owner was Icarus. Uneven pad deposits, yes, rust and damage, yes, but not warped. I'm sure that's what the OPC called it BTW, but it still isn't true

Jonny08 said: Trotmant said: excellent result - sorry if a noddy question, but how is this covered under warranty? surely your discs warpping are wear and tear on 14 plate car? or has it done very little mileage? The car has done 10K miles, which personally I do not think would be enough to require a new discs. I didn't have to challenge them at all, they just said "We've drove the car, we also experience the behaviour you have described, and have identified that there is warping of the discs. We will need to replace these and the pads" I was expecting them to try and bill me for the pads, but no - they said the pads requiring replacement is collateral from the discs warping. Either way, I bought and picked the car up last Monday, it really should have been picked up in PDI checks. I had no plan on footing the bill if there was one anyways :-) Also worth noting, I bought the car from a different OPC to where I've dropped it off for the work. (OPC I bought it from is 2 and a half hours away!) My treatment from all Porsche Centre's has been brilliant, great car, great experience so far :-) great result - good to see the OPC network working as it should.

Orangecurry said: Just FYI - there is no such thing as warped ventilated discs. Really. Think about it. What temperatures do you think will warp a metal disc cast in a foundry? Unless the previous owner was Icarus. Uneven pad deposits, yes, rust and damage, yes, but not warped. I'm sure that's what the OPC called it BTW, but it still isn't true Discs are cast, then the surfaces are machined flat. A severe heat cycle could risk warping the disc by microns, which a sensitive pedal would reveal, surely?

Exactly. You wouldn't be able to see the warping, even if you were touching the disc and spinning it by hand. It could be of the smallest margin, but you'd still feel it under the pedal. I warped some Brembo discs on my track car. I was adamant they were fine after inspecting them myself, but when I sent them back to Brembo they confirmed they were warped and it was a fault. It could still have simply been a combination of pad deposits and rust damage though.

griffter said: Discs are cast, then the surfaces are machined flat. A severe heat cycle could risk warping the disc by microns, which a sensitive pedal would reveal, surely? No - please do your own research. The most common way a disc is 'damaged' is by the pads not being bedded in properly, and/or someone sitting with their foot on the brakes whilst stationary when the brakes are (very) hot. This does fuse pad material unevenly to the disc in a way that can damage the disc permanently, but just in that area, so that even skimming doesn't last long. This is a thumping good read on the subject. http://www.stoptech.com/technical-support/technica...

Orangecurry said: This is a thumping good read on the subject. http://www.stoptech.com/technical-support/technica... It is a very interesting read - and I don't know enough to contradict most of it. However his discussion on Myth 6 is nonsense. Most cars I have owned have had an indication that the brake fluid level is low which is nothing to do with worn pads. Worn pads are usually detected by a contact buried in each disc pad which eventually, when the pad is thin enough breaks the surface and makes contact with the (cast iron as he says) disc making a circuit and illuminating a light. Given that he has made such a schoolboy error on that issue, I do wonder how accurate the rest of his thesis is - impressive though it sounds. Using the brake fluid level would a ludicrously inaccurate method of detecting brake wear. He is right that you shouldn't normally top up brake fluid at a service - but for the wrong reason. If you do top it up then when you come to replace the pads then pushing back the wheel cylinders will force the brake fluid displaced back into the reservoir and ultimately overflow the reservoir. Edited by bcr5784 on Tuesday 3rd November 17:01

Orangecurry said: No - please do your own research. The most common way a disc is 'damaged' is by the pads not being bedded in properly, and/or someone sitting with their foot on the brakes whilst stationary when the brakes are (very) hot. This does fuse pad material unevenly to the disc in a way that can damage the disc permanently, but just in that area, so that even skimming doesn't last long. This is a thumping good read on the subject. http://www.stoptech.com/technical-support/technica... I agree with everything you say, but I also believe brake discs can warp in certain circumstances. Any differential heating or cooling of the disc (Eg holding the pedal down while stationary) could lead to differential expansion of the vanes which would warp the friction surface. Any change to the crystalline structure of the metal could lead to permanent warping. The author of the linked document only claims they don't warp when mounted correctly to good condition components. Anyway the important thing is that the op's damaged discs are being replaced :-)