hard braking - something strange

[colski1961]

Hi,

still getting used to my Cayman R and now that the weather is improving getting more chances to test its capability, which is fun BUT I still have some concerns about the braking. Since moving from my R8 I've come to accept that the Porsche braking is less digital and more down to driver feel and actual pedal....which I now quite like however, I'd just like to check that what I'm experiencing is normal.....

OK, when travelling at 60-70 mph (or maybe a little more) and applying braking it seems to initially bite and start to slow and then there's a worrying pause where the car seems to have no braking applied at all - even though my foot is well down on the pedal, this isn't ABS type stutter (or not like any other ABS system I've ever come across) which is usually a very quick series of judders. It happens if I'm in Sport or Sport Plus modes too.

As I live 3 hours away from my nearest dealer and dont want to drive over there uneccessarily anyone got any thoughts or comments? I mean the car does stop but I am concerned that this feels like a loose caliper or similar......

Car is 10 months old, 3500 miles and Cayman R PDK

Thanks, Colin

 

[Buddy]

My Cayman S has the same brakes which I have no problems with and of course it is a manual. I read somewhere recently that the PDK has a freewheel feature and so no engine braking as in a manual gearchange. So as you lift off and get the initial effect of no drive going into over run it will then, I expect if my understanding is correct, go into "Freewheel" and then you are on only the brakes, not a problem as long as you are expecting it. Is it different if you drive in auto against manual modes? Or if you downshift?

 

[chrisH]

Cayman R does not have same brakes as Gen I Cayman S (07) , I think they are same as Gen II, S and there are quite a few changes including the feature you mention when you first hit the brakes. Colin why dont you ask your OPC the question as thats what they are for, after all you have a full warranty, although they will say the only way to check it is bring it in for them to test it themselves.

 

[glewis]

I've had my Cayman R for 6 months now and can't say I've noticed this phenomenon. As per previous response, give the OPC a call and ask them Ps. The Cayman R PDK doesn't have the "freewheel" feature mentioned above. That's something introduced on the latest 911 & Boxster with PDK (in addition to stop/start) to supposedly increase MPG and lower CO2, although I thought modern engines shut off the fuel completely on over-run anyway, whereas if you disengage the clutch you need a little fuel to prevent the engine stopping.

 

[flat6]

Porsche Assistance will happily come out to check out a concern with brakes.

 

[Buddy]

Fuel shut off on overrun has been a feature on Porsches at least since 1986 with the supply being reapplied once RPM reduced below 1400rpm at least that was the case on the 944's & 924S.

 

[colski1961]

thanks all for your inputs, gave it a further good testing yesterday and it only seems to be an issue once the brakes are warmed up....all gets stranger and stanger, I'll make the call to OPC and see what they say. Ta, Colin

 

[spyderman]

ORIGINAL: colski1961 OK, when travelling at 60-70 mph (or maybe a little more) and applying braking it seems to initially bite and start to slow and then there's a worrying pause where the car seems to have no braking applied at all - even though my foot is well down on the pedal...

Does the pedal jump or drop at all when this happens? When was your brake fluid changed? If you do a lot of heavy braking - and given you say it only happens when warm - you could possibly be boiling your brake fluid. Next change have them use something like Castrol SRF, or if an OPC, Porsche's own race fluid.

 

[colski1961]

Hi, no, no changes in the pedal at all (no jump or movements), I wouldn't expect it to be brake fluid boiling (or low) car is only a few months old and no I dont do a lot of harsh braking (no track driving). Thanks, Colin

 

[Motorhead]

As others have said Colin, unfortunately I think that you're going to have to take that long trip to your PC. Modern braking systems are now so complex because of the interaction between ABS and PSM, etc., that anything could be happening to cause the problem you've described and, clearly, it is a safety issue as you've probably lost confidence in the braking performance. Assumimg there's not an obvious mechanical problem, they can run a diagnostic check and will probably bleed the brakes as a precaution. Hope you get it fixed soon and get back to enjoying the driving experience in this lovely June weather..! Keep us posted on progress. Jeff

 

[colski1961]

Hi all, just an update, spoke to OPC Aberdeen yesterday and they suggested I 'drop in' with the car when passing - unlikley when I live 130 miles away However, suggested that I'll carry on as is and if it gets worse then make the journey. The car still seems to stop pretty well so maybe it's nothing but we'll see....will keep you updated. Cheers, Colin

 

[barrie nunn]

why not make the journey now before its to late... whats 130 miles when your driving a 50/60 grand car mate.. simple maths innit

 

[ChrisW]

I agree, why take a chance ?

 

[964RS]

ORIGINAL: colski1961 Hi, still getting used to my Cayman R and now that the weather is improving getting more chances to test its capability, which is fun BUT I still have some concerns about the braking. Since moving from my R8 I've come to accept that the Porsche braking is less digital and more down to driver feel and actual pedal....which I now quite like however, I'd just like to check that what I'm experiencing is normal..... OK, when travelling at 60-70 mph (or maybe a little more) and applying braking it seems to initially bite and start to slow and then there's a worrying pause where the car seems to have no braking applied at all - even though my foot is well down on the pedal, this isn't ABS type stutter (or not like any other ABS system I've ever come across) which is usually a very quick series of judders. It happens if I'm in Sport or Sport Plus modes too. As I live 3 hours away from my nearest dealer and dont want to drive over there uneccessarily anyone got any thoughts or comments? I mean the car does stop but I am concerned that this feels like a loose caliper or similar...... Car is 10 months old, 3500 miles and Cayman R PDK Thanks, Colin

Yike. Take it in now before it kills you. Clearly something not right. Should be diagnosed immediately the OPC. I've had brake failure on the track, in a safer (?!) environment than the road, and I've since become pragmatic about brakes.

 

[rob.kellock]

I have Boxster Spyder which is mechanically close to Cayman R albeit mine is manual. I have never experienced what you describe, even on a track day. I have just spent some miles in a courtesy Boxster S PDK and was surprised that the brakes felt quite different to the Spyder's which I initially put down to weight. It may be a PDK thing? Either way, I'd have it checked out if you are concerned. Your OPC will collect and return your car surely?

 

[colski1961]

Hi Guys, thanks for all the advice and comments, think I have it sorted. The sensation (and that's all it was) was caused by the PDK changing down (engine braking) the combination of a change down in gear, engine note and braking conspired to cause the feeling that the brakes had lifted, no such thing, all prefect and working as they should (phew)! Cheers, Colin