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997.2 GT3 brake problem - long pedal when hot

Heat would imply fade, but you said no fade?

Those of us that are economically minded would flip the pads left to right after about 40% wear, this way you can get max use out of them. RS29's do seems to fall off towards the end of their thickness. One of the good things about PF is that you can run them to the backing plates pretty much, endless too. I assume this is to do with the back plate material?
 
I had a similar uneven wear on r29 pads, what are we saying is the course?
 
Any pad wil wear like that. The bottom of the caliper grips first and hardest, the "front" of the grip so to speak. The pistons are different sizes to compensate and even out the pressure but its still that part of the pad that hits the disc first.
 
Different calipers then?

A friend has the Alcon kit which comes with Alcon calipers on a GTR which is a lot heavier than a GT3. No problems at all.
 
mm450exc said:
And will be using RS19 next.

Why?

RS19 are not as good a pad for track work, particularly on the front. I have heard of people occasionally using them on the rear in an effort to eliminate squeal when on the road but never come across anyone using them on the front.
 
When you look at the RS19 spec the difference is very marginal. Before the 29 came along they were the de facto pad i thought.

I say this as i have a set of 19's in the garage which will go on next. My exhaustive Internet research (a browse through google) suggests there's not a whole lot of difference. RS29 designed to work a little hotter?
 
Pad specs don't tell the whole story though. The wear rate on the RS19 is significantly higher which is why the RS29 was developed as a pad that would last better for endurance race use.

By all means try them, but I think you'll find the RS29 is superior in every way.
 
Senoj said:
Any pad wil wear like that. The bottom of the caliper grips first and hardest, the "front" of the grip so to speak. The pistons are different sizes to compensate and even out the pressure but its still that part of the pad that hits the disc first.


So are we saying this is normal? This was the first time I've used R29 pads not noticed this on my other pads (PF). Anyway I've gone back to PF08 pads.
 
Yes, they will all wear faster on the leading edge. Those pics are particularly extreme & I suspect that there's a tiny amount of air in the calliper at the top which is why the pads have barely worn there. It's more normal to see a difference of one or two millimetres top to bottom on a half-worn pad. The PF's will exhibit this wear pattern too.
 
NXI20 said:
Yes, they will all wear faster on the leading edge. Those pics are particularly extreme & I suspect that there's a tiny amount of air in the calliper at the top which is why the pads have barely worn there. It's more normal to see a difference of one or two millimetres top to bottom on a half-worn pad. The PF's will exhibit this wear pattern too.

Ok thanks, already done a brake fluid change and bleed, so will see how we get on :thumb:
 
Cunno said:
Are you sure it's fade? The reason I ask is that the 997 abs system is different to 996s. You can get the abs system to cut in and trigger what people refer to as the ice mode. Basically it feels like fade, peddle goes soft and you seem to have about 60% or less of your normal braking force, but it's the abs system going nuts. Can be triggered in 2 ways bumpy track surfaces within braking zone and going to aggressive from throttle to brakes.

When it happens if you come off the brake and re apply does it cure itself ? If so this is the abs system and you need to modify your braking style or buy a cup abs system at £8000 :sad:

If every thing else looks ok I expect this is what's happening.

Some back ground here.

http://rennlist.com/forums/997-gt2-gt3-forum/534934-well-abs-ice-mode-finally-got-me.html

http://rennlist.com/forums/997-gt2-gt3-forum/866677-abs-delete-and-ice-mode.html


http://rennlist.com/forums/997-gt2-gt3-forum/801844-ice-mode.html



That is fascinating to read. Good sleuthing Jon.
 
NXI20 said:
Yes, they will all wear faster on the leading edge. Those pics are particularly extreme & I suspect that there's a tiny amount of air in the calliper at the top which is why the pads have barely worn there. It's more normal to see a difference of one or two millimetres top to bottom on a half-worn pad. The PF's will exhibit this wear pattern too.


The pads in the picture are pretty much identical to the ones that I just replaced on my 997.2 GT3 - it is normal for the car on Pagids. Which explains much (see my earlier comment about the OP's symptoms being the de-facto indicator that the pads are spent). The 997.2 wears its pads much more trapezoidally than the 996 used to and there are only 2 ways around it that I know of. The first is to flip the pads when part worn as Danny suggested. The other is to spend the crazy money charged in the UK for Endless pads...

Also noteworthy while we are on the subject is that the 997.2 wears the rear pads on the outer face faster than the inner, but in general uniformly rather than in the trapezoid fashion of the fronts. I am not convinced that there is much to be gained by flipping those, but it is handy to know that the one that you can just look at on the outside is the one wearing faster and that it ought to be uniform top to bottom.
 
All brands of pads do this. Its an artefact of the six pistons and long (ish) pad rather than the pads maker i believe.
 
How does the uneven wear create a long pedal as per the OPs problem and by rotating or changing pads cure it? Or do we think his issue will remain?
 

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