Brake Issue On Brand New Carrera S

[ianp]

I just picked up my 2010 Carrera S last week. Everthing is great except three times now I have felt a disconcerting 'clunk' through the pedal when braking. Twice it was reversing down my (steep) driveway while turning the wheels (not full lock by any means) and third time was a downhill left corner in 3rd gear - when I braked in the corner it did it. It's like something moves momentarily. It can't be reproduced at will unfortunately.

At no time have I lost braking but I've had may cars and never felt this kind of thing through the pedal before.

In a brief conversation with my sales guy, he said it may be the floating calipers bedding in - which sounded bogus to me. Anyway I am taking it in Tuesday and wondered if folks with more Porsche knowledge than me had any insights into what this could be or advice on what to ask the dealer to do? I expect they will come back with not being able to reproduce it or finding anything wrong.

Thanks.

[paulgoeke]

I guess your sure it's not the ABS. I was surprised that mine engaged at such a low speed in reverse but all it takes is sufficient pressure to threaten to lock the wheels. ou describe two scenarios where that could occur.

[fast eddie]

If this occurs while going very slowly, it may be the incline anti roll function. Read the maunal, if you have a manual transmission which I do, it occasionally will clunk when starting to move on an incline. If yours is an automatic transmission, I don't know. Good luck.

[ianp]

Thanks for the replies. It is a manual - for the slow going backwards down the driveway occurances I can believe it's the ABS and/or hill assist. The one I find strange is the occurance going faster downhill in 3rd gear. I wasn't pushing it so there was no need for ABS.

Anyway will see what the dealer says/finds tomorrow. I expect nothing and I'll need to do alot more miles to get to the bottom of it. It's actually going into the dealer for a different minor issue - all the POI categories in the Navi are in German and they need to reset the whole system to fix that!

[PorscheTechnician]

Thanks for the replies. It is a manual - for the slow going backwards down the driveway occurances I can believe it's the ABS and/or hill assist. The one I find strange is the occurance going faster downhill in 3rd gear. I wasn't pushing it so there was no need for ABS.

Anyway will see what the dealer says/finds tomorrow. I expect nothing and I'll need to do alot more miles to get to the bottom of it. It's actually going into the dealer for a different minor issue - all the POI categories in the Navi are in German and they need to reset the whole system to fix that!

If it is not too far from the dealer and assuming you don't mind, have the tech go over to where it happened and try to replicate it.

[ianp]

Thanks for the replies. It is a manual - for the slow going backwards down the driveway occurances I can believe it's the ABS and/or hill assist. The one I find strange is the occurance going faster downhill in 3rd gear. I wasn't pushing it so there was no need for ABS.

Anyway will see what the dealer says/finds tomorrow. I expect nothing and I'll need to do alot more miles to get to the bottom of it. It's actually going into the dealer for a different minor issue - all the POI categories in the Navi are in German and they need to reset the whole system to fix that!

If it is not too far from the dealer and assuming you don't mind, have the tech go over to where it happened and try to replicate it.

Thanks for the advice. It went into the dealer yesterday and as predicted they could not replicate - the dealer is in a very flat area and the location where the issue happened in 3rd gear is about 20 mins away. They did a full brake check, and everything checked out fine so the theory is it's just the ABS working. I've only done 250 miles so we agreed I'll live with the car for some miles and see how we get to know each other :-)

That said, I've had several recent Audis and the ABS never felt like a single 'clunk' through the pedal. Usually it's just a pulsing. We'll see ... this is my first Porsche.

[jsmoore3]

Interesting discussion. I have a 2009 Carrera S with a Manual transmission that I got in Dec 2009. I live on a steep driveway and have had the same clunk at very slow speeds when turning the wheel as I back out. I have also gotten the clunk when turning sharply out of a parking spot. The first time it happened I thought I had hit the car next to me.

To date I have just ignored it. I am interested to see what you find out.

[Loren]

Interesting discussion. I have a 2009 Carrera S with a Manual transmission that I got in Dec 2009. I live on a steep driveway and have had the same clunk at very slow speeds when turning the wheel as I back out. I have also gotten the clunk when turning sharply out of a parking spot. The first time it happened I thought I had hit the car next to me.

To date I have just ignored it. I am interested to see what you find out.

Tell your dealer have write the exact description you give on the repair order. Then when something fails 2 years from now you still have a warranty claim.

[phillipj]

Great advice Loren...........

[ADias]

Thanks for the advice. It went into the dealer yesterday and as predicted they could not replicate - the dealer is in a very flat area and the location where the issue happened in 3rd gear is about 20 mins away. They did a full brake check, and everything checked out fine so the theory is it's just the ABS working. I've only done 250 miles so we agreed I'll live with the car for some miles and see how we get to know each other :-)

That said, I've had several recent Audis and the ABS never felt like a single 'clunk' through the pedal. Usually it's just a pulsing. We'll see ... this is my first Porsche.

You seem to imply that you observe that when the car is on an incline. Could the noise be the release of the brake assist (which is normal)?

Edited June 25, 2010 by ADias

[ianp]

I don't think it is the hill assist (is that what you mean by brake assist?) as I haven't actually stopped moving when it happens (and one of the occurrences was in 3rd gear around 45mph!). The hill assist has helped me out several times and there is no clunk.

The more I get to know the car the more I think it is just the ABS kicking in over-aggressively. Today it did it and after the clunk there was a more familiar pulsing felt through the pedal. If so it is rather crude as there is no chance of slipping on my dry driveway, and I expected something a bit more refined from a Porsche. Of course, overall the car is awesome!