Bedding in PCCB pads

[996GT2]

Car is having new front pads tomorrow. I've heard that there is a procedure that needs to be followed to bed them in properly, anyone know it or have a link to it?


Cheers

[993rsr]

From Porsche:

Note on bedding in the new brake pads
New brake pads require a slightly longer bedding-in period for PCCB brake discs than cast iron brake discs.
In general, the following applies: new brake pads must be worn in (bedding-in period), their optimum braking effect is therefore not reached until after a few hundred kilometres. The slightly reduced braking effect must be compensated for by increased pressure on the brake pedal. The same also applies after a brake disc change

[996GT2]

Cheers, so essentially just press the brake pedal a bit harder until they start working properly


I thought there was some procedure of braking from 100 to 0 a few times, then 100 to 50 or something? Maybe that was for new PCCB discs not pads.

[Slippydiff]

996GT2 said:

I thought there was some procedure of braking from 100 to 0 a few times, then 100 to 50 or something? Maybe that was for new PCCB discs not pads.

Just use them sensibly for the first couple of hundred miles, no heavy braking , no maximum attack 120mph down to 30mph type stuff either. Start increasing speeds and pressure as they bed in and their efficiency improves.

HTH

[robmug]

Sorry, there's more to bedding in brakes than the above.

Bedding in the brakes.

As for steel discs, bedding in is ESSENTIAL to allow a friction film to develop between the pad and disc. So, more info:

Summarised from Total 911 feature in Issue 48

Info supplied by SGL, the manufacturer of the discs.

The aim of the first phase is to create a sufficiently high contact between brake disc and brake pad. The purpose of phases 2&3 is to fully develop the friction film between pad & disc.


Phase 1. 15 brake applications of 10 seconds each at minimum deceleration (20%) from 100mph to 50mph at approx 30 second intervals.

Phase 2. 15 brake applications of 7 seconds each at low deceleration (30%) from 100mph to 50mph at approx 1 minute intervals

Phase 3. 15 brake applications of 7 seconds each at medium deceleration (40%) from 110mph to 50mph at approx 2 minute intervals. This phase can be reduced by 2 or 3 applications at maximum deceleration (ABS control range) from 100-110mph down to zero. Time interval between these should be around 3 minutes.

[993rsr]

robmug said:

Sorry, there's more to bedding in brakes than the above.

Bedding in the brakes.

As for steel discs, bedding in is ESSENTIAL to allow a friction film to develop between the pad and disc. So, more info:

Summarised from Total 911 feature in Issue 48

Info supplied by SGL, the manufacturer of the discs.

The aim of the first phase is to create a sufficiently high contact between brake disc and brake pad. The purpose of phases 2&3 is to fully develop the friction film between pad & disc.


Phase 1. 15 brake applications of 10 seconds each at minimum deceleration (20%) from 100mph to 50mph at approx 30 second intervals.

Phase 2. 15 brake applications of 7 seconds each at low deceleration (30%) from 100mph to 50mph at approx 1 minute intervals

Phase 3. 15 brake applications of 7 seconds each at medium deceleration (40%) from 110mph to 50mph at approx 2 minute intervals. This phase can be reduced by 2 or 3 applications at maximum deceleration (ABS control range) from 100-110mph down to zero. Time interval between these should be around 3 minutes.

The paragraph I quoted is taken from the CGT 980 workshop manual. I've used the instruction from Porsche when bedding in new PCCB rotors or pads with no problems. I would have thought that if the method detailed above from SGL Carbon was necessary it would be in the factory workshop manuals.

[So'ton Ben]

Just as an aside, how much did the pads cost? I have PCCBs on my C4S and one day will need to change the pads. Its only done 35k when is it generally accepted that they will need changing?

Thanks

[996GT2]

So'ton Ben said:

Just as an aside, how much did the pads cost? I have PCCBs on my C4S and one day will need to change the pads. Its only done 35k when is it generally accepted that they will need changing?

Thanks

Front pads were around £320 from Porsche Reading. Sid at RSJ Sports Cars is fitting them tomorrow.

I've been advised that my front pads are good for thousands more miles but I'm off to the 'ring in 2 weeks so it's a case of better safe than sorry. I've covered nearly 20,000 miles in 2 years including 10 track days since buying the car and haven't replaced the pads - plus the first generation PCCBs at 62,000 miles are looking very good, had the car on a ramp last week and had a good look around all of them.

Edited by 996GT2 on Monday 10th May 17:04

[So'ton Ben]

Thanks, thats a relief then! £320 doesn't sound too bd from an OPC considerimg they are PCCB. I have been a bit worried about them!

Thanks

[Slippydiff]

robmug said:

Sorry, there's more to bedding in brakes than the above.

Bedding in the brakes.

As for steel discs, bedding in is ESSENTIAL to allow a friction film to develop between the pad and disc. So, more info:

Summarised from Total 911 feature in Issue 48

Info supplied by SGL, the manufacturer of the discs.

The aim of the first phase is to create a sufficiently high contact between brake disc and brake pad. The purpose of phases 2&3 is to fully develop the friction film between pad & disc.


Phase 1. 15 brake applications of 10 seconds each at minimum deceleration (20%) from 100mph to 50mph at approx 30 second intervals.

Phase 2. 15 brake applications of 7 seconds each at low deceleration (30%) from 100mph to 50mph at approx 1 minute intervals

Phase 3. 15 brake applications of 7 seconds each at medium deceleration (40%) from 110mph to 50mph at approx 2 minute intervals. This phase can be reduced by 2 or 3 applications at maximum deceleration (ABS control range) from 100-110mph down to zero. Time interval between these should be around 3 minutes.

Sorry Rob but what you've described didn't work for me ! and I have two sets of VERY expensive Pagid pads to prove it (a set of RS29s and a set of P30s)

However the last set of RS29s I had fitted to the AP six pot/356mm PF discs on the front of the CSL were "bedded in" using the technique I've mentioned, once that was completed the transfer layer was applied by "spirited" road use and they've worked brilliantly thereafter !

I tried the technique you've highlighted on my 996 GT2 and ended up with two sets of scrap pads for my troubles . . . .

With regards to your comments on the transfer layer being essential for the optimal coefficient of friction on steel discs, you're correct, however your comments appear to indicate that it's not a requirement with PCCBs. (It is)

As I understand it the process of ensuring the application of a transfer layer can only be carried out by raising the temperature of the pads to the point whereby the face of the pad becomes "liquid", this material is then deposited on the disc face and provides the friction surface required for the optimal coefficient of friction.

Info supplied by Surface Transforms, they make ceramic discs for plane and train brake systems, not to mention the ceramic discs for a certain Swedish supercar manufacturer . . .

Carrying this out on a disc and pad combination that hasn't been bedded in to ensure the wearing faces are maximised can lead to high spots which in turn become hot spots on the disc face, in the worst case scenario if this is ignored the disc will end up with some areas of the face material becoming harder than the rest of the disc. These "hard" areas have a very poor coefficient of friction and can lead to vastly decreased brake efficiency (and also give the impression that the brake discs are warped when they are not)

All you wanted to know about brakes here : http://www.stoptech.com/tech_info/wp_warped_braked...

[robmug]

Slippydiff said:

robmug said:

As for steel discs, bedding in is ESSENTIAL to allow a friction film to develop between the pad and disc. So, more info:

With regards to your comments on the transfer layer being essential for the optimal coefficient of friction on steel discs, you're correct, however your comments appear to indicate that it's not a requirement with PCCBs. (It is)

As I understand it the process of ensuring the application of a transfer layer can only be carried out by raising the temperature of the pads to the point whereby the face of the pad becomes "liquid", this material is then deposited on the disc face and provides the friction surface required for the optimal coefficient of friction.

No, I said that it IS essential for PCCBs just as it is for steel brakes.

You and I are in agreement that a transfer layer needs putting on the disc; what we appear to disagree on is the method.

I have always taken issue that Pagid's bedding in instructions (just as for the PCCBs that I posted) suggest that effective bedding-ing comes from repeated deceleration from way over national speed limit - so there's no way that their process can be realistically done on UK roads.

[Slippydiff]

robmug said:

Slippydiff said:

robmug said:

As for steel discs, bedding in is ESSENTIAL to allow a friction film to develop between the pad and disc. So, more info:

With regards to your comments on the transfer layer being essential for the optimal coefficient of friction on steel discs, you're correct, however your comments appear to indicate that it's not a requirement with PCCBs. (It is)

As I understand it the process of ensuring the application of a transfer layer can only be carried out by raising the temperature of the pads to the point whereby the face of the pad becomes "liquid", this material is then deposited on the disc face and provides the friction surface required for the optimal coefficient of friction.

No, I said that it IS essential for PCCBs just as it is for steel brakes.

You and I are in agreement that a transfer layer needs putting on the disc; what we appear to disagree on is the method.

I have always taken issue that Pagid's bedding in instructions (just as for the PCCBs that I posted) suggest that effective bedding-ing comes from repeated deceleration from way over national speed limit - so there's no way that their process can be realistically done on UK roads.

Ah apologies, I think what you meant was : As is the case for steel discs, bedding in is essential for the PCCBs . . .

I'm not disagreeing, I'm merely saying that there is an alternative procedure for the bedding in procedure. That procedure is a totally separate procedure to applying the transfer layer and it (the bedding in) can be done gently over a period of several hundred ROAD miles, thereafter you apply the transfer layer using Pagids recommended method (there is no other way to do this than to get the pads up to their working temperature, on this we both agree)

The bedding in AND transfer layer application process you are advocating is correct if you are using the Pagid pads for their intended purpose, that (in the case of the RS29S) being endurance racing.

You'll note that Pagids instructions make no mention of road use . . . . and clearly no right minded race team is going to go out and drive several hundred miles to gently bed in new pads (as I'm advocating) PRIOR to going through the process of applying the transfer layer.