GT2 Brake Issues
Discussion
Due to the PCCBs failing shortly after I purchased the car, I had the JZM floating Alcons fitted in December of last year.
I supplied "standard" GT3 MK2 (ie six pot) OPC sourced yellow brake pads.
No instructions were given for bedding the pads in, so I did what I'd normally do with new pads and discs.
This being to brake gently for the first few hundred miles, whilst slowly building up speeds and pressure as the pads bedded into the discs.
Whilst originally the new brakes felt better than the shot ceramics, they then reached a plateau and subsequently started to deteriorate (now to the point they're almost as ineffectual as the PCCBs were after a few high speed stops)
Whilst making enquires as to why this has happened, I was told the Porsche yellow pads I've had fitted are in fact Pagid RS19s.
Subsequent investigation (confirmed when I pulled the pads this morning) showed the pads to indeed be Pagids, but a compound called P90 NOT RS19.
Can anyone tell me what the correct bedding procedure is for standard OPC GT3 MK2 pads should be?
Having removed the pads from one side of the car I've inspected them and found them to be in poor shape
As can be seen from this picture the surface appears to be badly glazed. (Click on pictures to get a larger version)
I've attempted to remove the glaze with some 60 grit emery cloth, and whilst it has removed the glaze, the surface of the two pads look totally different to each other now (as can be seen by the red highlighting)
Can anyone tell me whether these pads are now shot ?
Having been shafted by Reading over the original PCCBs and invested in what is supposed to be THE recommended fix for the brakes on these cars, by fitting the Alcons, I find the brakes still aren't working correctly.
I am, as you would imagine very f*cked off with the whole episode now
Any ideas please ?
I supplied "standard" GT3 MK2 (ie six pot) OPC sourced yellow brake pads.
No instructions were given for bedding the pads in, so I did what I'd normally do with new pads and discs.
This being to brake gently for the first few hundred miles, whilst slowly building up speeds and pressure as the pads bedded into the discs.
Whilst originally the new brakes felt better than the shot ceramics, they then reached a plateau and subsequently started to deteriorate (now to the point they're almost as ineffectual as the PCCBs were after a few high speed stops)
Whilst making enquires as to why this has happened, I was told the Porsche yellow pads I've had fitted are in fact Pagid RS19s.
Subsequent investigation (confirmed when I pulled the pads this morning) showed the pads to indeed be Pagids, but a compound called P90 NOT RS19.
Can anyone tell me what the correct bedding procedure is for standard OPC GT3 MK2 pads should be?
Having removed the pads from one side of the car I've inspected them and found them to be in poor shape
As can be seen from this picture the surface appears to be badly glazed. (Click on pictures to get a larger version)
I've attempted to remove the glaze with some 60 grit emery cloth, and whilst it has removed the glaze, the surface of the two pads look totally different to each other now (as can be seen by the red highlighting)
Can anyone tell me whether these pads are now shot ?
Having been shafted by Reading over the original PCCBs and invested in what is supposed to be THE recommended fix for the brakes on these cars, by fitting the Alcons, I find the brakes still aren't working correctly.
I am, as you would imagine very f*cked off with the whole episode now
Any ideas please ?
Edited by slippydiff on Saturday 17th February 12:02
slippydiff said:
No instructions were given for bedding the pads in, so I did what I'd normally do with new pads and discs.
This being to brake gently for the first few hundred miles, whilst slowly building up speeds and pressure as the pads bedded into the discs.
Edited by slippydiff on Saturday 17th February 12:02
There will be better experts than me along I'm sure, but I was given very different advice to bedding in new pads & discs, when I had the sam combination of discs & pads fitted.
I was told fine & quiet empty piece of road & take the discs & pads through several heavy (70%) braking cycles from a "decent" speed, but never actually stopping the wheels.
So come on experts, correct bedding in practice??
rob_j said:
slippydiff said:
No instructions were given for bedding the pads in, so I did what I'd normally do with new pads and discs.
This being to brake gently for the first few hundred miles, whilst slowly building up speeds and pressure as the pads bedded into the discs.
Edited by slippydiff on Saturday 17th February 12:02
There will be better experts than me along I'm sure, but I was given very different advice to bedding in new pads & discs, when I had the sam combination of discs & pads fitted.
I was told fine & quiet empty piece of road & take the discs & pads through several heavy (70%) braking cycles from a "decent" speed, but never actually stopping the wheels.
So come on experts, correct bedding in practice??
I was informed along the same lines when I had my 12Piston Tarox BBK fitted to my previous e39 M5. Half a dozen heavy stops from 60-70mph in succesion do bed them in, then drive with minimal braking for 10-15mins to let things cool off. The result were the best brakes I have ever experienced on a road car to date.
I'm sure that whichever independent/specialist you talk to will give similar bedding-in advice.
C.
I should point out the car is used solely on the road, hence the reason I went for "standard" OPC sourced pads.
I wanted instant bite from cold with good modulation and no squeaking.
I (mistakenly?) thought that as I'd sourced "roadgoing" pads the bedding in process would be similar to that I used on my previous MK1 GT3 when I replaced the pads and discs.
Below is quoted from Pagid USA with reference to bedding in procedure for their RACE pads
RACING PAD BEDDING
PLEASE NOTE:
IT IS IMPERATIVE THAT THE BEDDING IN PROCEDURES ARE BEING DONE ONLY ON
A RACE TRACK. PAGID RACING MATERIAL IS NOT LEGAL FOR STREET USE.
1. GEOMETRIC ALIGNMENT OF PAD SURFACE TO BRAKE DISC BASIC BEDDING IN
3-4 stops with light to medium brake pressure from approximately 150 km/h (90 MPH)
to approximately 100 km/h (65 MPH).
Distance between each brake stop is approximately 300-400 meters (300 to 400 yards).
The pads should not reach temperatures above 300-400 Centigrade (550 to 750 Fahrenheit)
during bedding in.
Blocking of the air ducts might be helpful to reach appropriate temperatures quicker.
2. IMMEDIATELY AFTER BEDDING IN AT HIGH SPEED
One stop with medium to heavy brake pressure without allowing the brakes to lock from
approximately 180 km/h (110 MPH) to approximately 100 km/h (65 MPH).
Recovery stops with light brake pressure 2-3 times.
Repeat the high speed stops, including recovery stops, 1-2 times.
Allow a cooling-off distance of approximately 500 m (500 yards) between high speed stops.
Joking aside (and to give an idea of just how poor the brakes currently are on the car) my five year old 90,000 plus mile 330 diesel saloon stops more convincingly from 100-110 mph on a regular basis........
Do other Alcon users find the brakes "growl" noisily from high speeds when warmed up ? or is this happening because the pads are shot ?
If this noise is a normal characteristic of the Alcons I shall most likely remove them and fit the standard Porsche 350mm single piece steels to the front of the car.
If I do decide to do this, does anyone want to purchase the Alcons ? (10 weeks and 3000 miles "old" )
I wanted instant bite from cold with good modulation and no squeaking.
I (mistakenly?) thought that as I'd sourced "roadgoing" pads the bedding in process would be similar to that I used on my previous MK1 GT3 when I replaced the pads and discs.
Below is quoted from Pagid USA with reference to bedding in procedure for their RACE pads
RACING PAD BEDDING
PLEASE NOTE:
IT IS IMPERATIVE THAT THE BEDDING IN PROCEDURES ARE BEING DONE ONLY ON
A RACE TRACK. PAGID RACING MATERIAL IS NOT LEGAL FOR STREET USE.
1. GEOMETRIC ALIGNMENT OF PAD SURFACE TO BRAKE DISC BASIC BEDDING IN
3-4 stops with light to medium brake pressure from approximately 150 km/h (90 MPH)
to approximately 100 km/h (65 MPH).
Distance between each brake stop is approximately 300-400 meters (300 to 400 yards).
The pads should not reach temperatures above 300-400 Centigrade (550 to 750 Fahrenheit)
during bedding in.
Blocking of the air ducts might be helpful to reach appropriate temperatures quicker.
2. IMMEDIATELY AFTER BEDDING IN AT HIGH SPEED
One stop with medium to heavy brake pressure without allowing the brakes to lock from
approximately 180 km/h (110 MPH) to approximately 100 km/h (65 MPH).
Recovery stops with light brake pressure 2-3 times.
Repeat the high speed stops, including recovery stops, 1-2 times.
Allow a cooling-off distance of approximately 500 m (500 yards) between high speed stops.
Joking aside (and to give an idea of just how poor the brakes currently are on the car) my five year old 90,000 plus mile 330 diesel saloon stops more convincingly from 100-110 mph on a regular basis........
Do other Alcon users find the brakes "growl" noisily from high speeds when warmed up ? or is this happening because the pads are shot ?
If this noise is a normal characteristic of the Alcons I shall most likely remove them and fit the standard Porsche 350mm single piece steels to the front of the car.
If I do decide to do this, does anyone want to purchase the Alcons ? (10 weeks and 3000 miles "old" )
Edited by slippydiff on Saturday 17th February 12:40
Edited by slippydiff on Saturday 17th February 12:42
When we have new pads fitted I`ll do a couple of gentle laps then brake hard from say 120 to 60, let the brakes cool then repeat the process building up a bit of speed, let them cool again and bob`s your uncle.
Pottering around for a couple of hundred miles isn`t going to put the pads through any heat cycles. not sure of the chemistry but it sems to work. I`ve never had any issues with pads and we do get through a few. We also expect full life on the longer 24 hour races. We bed pads in and then remove them so they can be re-fitted when required during a race.
This is the problem sourcing parts seperately rather than going to someone and getting them to do the whole job. There is a chance parts may not be what you epect and the suppliers asume you have specialist knowledge. A person doing the whole job will talk you through their products and services.
Henry
Pottering around for a couple of hundred miles isn`t going to put the pads through any heat cycles. not sure of the chemistry but it sems to work. I`ve never had any issues with pads and we do get through a few. We also expect full life on the longer 24 hour races. We bed pads in and then remove them so they can be re-fitted when required during a race.
This is the problem sourcing parts seperately rather than going to someone and getting them to do the whole job. There is a chance parts may not be what you epect and the suppliers asume you have specialist knowledge. A person doing the whole job will talk you through their products and services.
Henry
I have no experience of Porsche brakes. However bedding in procedures shouldn't be that different on other cars. I have always bedded in new pads by braking 4 or 5 times from 80 - 90 mph down to 30 - 40 mph with moderate to heavy pedal pressure. One of my vehicles uses Black Diamond discs and Mintex 1155 pads. The other uses original Honda OEM discs (DC5 with Brembo calipers) and DS2500 pads. These pads are intended for track work, but I never had any problem with initial bite in normal road use.
I have found on track that continual heavy use of the brakes does result in a "growling" sound when the brakes are applied. I have never had pads glaze like your examples. I suspect may have been due to inadequate heat being generated during bedding in. The idea of generating sufficient heat during the bedding in process is to expel volatile products from the pad compound. It these volatile products that contribute to the glazing.
Having gound off the glaze try bedding the pads again, but with bigger retardations and more pedal pressure.
I have found on track that continual heavy use of the brakes does result in a "growling" sound when the brakes are applied. I have never had pads glaze like your examples. I suspect may have been due to inadequate heat being generated during bedding in. The idea of generating sufficient heat during the bedding in process is to expel volatile products from the pad compound. It these volatile products that contribute to the glazing.
Having gound off the glaze try bedding the pads again, but with bigger retardations and more pedal pressure.
henry-f said:
When we have new pads fitted I`ll do a couple of gentle laps then brake hard from say 120 to 60, let the brakes cool then repeat the process building up a bit of speed, let them cool again and bob`s your uncle.
Pottering around for a couple of hundred miles isn`t going to put the pads through any heat cycles. not sure of the chemistry but it sems to work. I`ve never had any issues with pads and we do get through a few. We also expect full life on the longer 24 hour races. We bed pads in and then remove them so they can be re-fitted when required during a race.
This is the problem sourcing parts seperately rather than going to someone and getting them to do the whole job. There is a chance parts may not be what you epect and the suppliers asume you have specialist knowledge. A person doing the whole job will talk you through their products and services.
Henry
Pottering around for a couple of hundred miles isn`t going to put the pads through any heat cycles. not sure of the chemistry but it sems to work. I`ve never had any issues with pads and we do get through a few. We also expect full life on the longer 24 hour races. We bed pads in and then remove them so they can be re-fitted when required during a race.
This is the problem sourcing parts seperately rather than going to someone and getting them to do the whole job. There is a chance parts may not be what you epect and the suppliers asume you have specialist knowledge. A person doing the whole job will talk you through their products and services.
Henry
It seems that even though I presumed (never a good idea !) the genuine Porsche GT3 pads would be a "road" compound they are anything but.........more likely they are a fast road/odd bit of trackwork compound and thus neeeded bedding in like a true race pad rather than a "bed in gently for the first 100 miles" road compound.
Thanks all, looks like a new set of pads will be needed as I've obviously glazed this set up by being too gentle with them and then killed them with excessive heat
P90 is the standard OPC brake pads for the GT3.
From your description and photos all you have done is glaze the pads through insufficient heat generation.
As the car is a GT3 you would expect it to be fitted with fast road pads for road use wouldn't you??
Having to pootle round town will tend to glaze the pads and you have reprinted Pagids correct bedding in procedure, so all is not lost.
You have removed the glaze so all you have to do now is just bed them in again correctly and you will be fine. If they glaze again in the future (when they start growling a bit) just follow the bedding in procedure again to restore stopping power - no need to sand them off.
The brake pads are fine. If you take a look at a set that have been used heavily on track you will be shocked at the state of them - crazed all over and still going strong!
From your description and photos all you have done is glaze the pads through insufficient heat generation.
As the car is a GT3 you would expect it to be fitted with fast road pads for road use wouldn't you??
Having to pootle round town will tend to glaze the pads and you have reprinted Pagids correct bedding in procedure, so all is not lost.
You have removed the glaze so all you have to do now is just bed them in again correctly and you will be fine. If they glaze again in the future (when they start growling a bit) just follow the bedding in procedure again to restore stopping power - no need to sand them off.
The brake pads are fine. If you take a look at a set that have been used heavily on track you will be shocked at the state of them - crazed all over and still going strong!
Pagid Racing Compound Characteristics
RS 4-2-1 Black
A high performance compound with low fading characteristics and high cold friction. The most comfortable medium friction sport compound. Rotor friendly and OE on various Ferrari, Lamborgini, Lotus, Bugatti and Corvette (Callaway) models. Suitable for street and light track use.
RS 4-2 Blue
A medium friction racing compound with good cold friction and fading resistance up to 500°C ( 930°F).
The 4-2 compound has an acceptable rotor wear rate and a very good modulation (adjustment). It is a Classic Rally compound and is used also for small Single-Seater ( F3, F-Ford, Club Racing and Showroom Stock).
RS 4-4 Orange
This compound has a very good fade resistance and a higher average friction value than the RS 4-2. It is rotor friendly with predictable, non-aggressive friction behaviour (stable torque). Fading resistance up to 560°C (1.050°F). It is a very good rear compound for Touring Car applications in combination with RS 14 front pads. It’s main application is Porsche 911 racing. It is used on either Short Track or Long Distance; also for front and rear axles. It is also used on BMW Showroom Stock, all other Touring-Cars and Single- Seater up to F3.
RS 14 Black
This is a medium high friction value ceramic type compound with very good modulation, high fade resistance, low heat conductivity, and a good wear rate up to a temperature of 650°C (1.200°F). It is kind on discs, with visible grooving, but a limitation of hairline cracks. Applications: NASCAR, CART, F3, Touring cars, GT cars, WSC, Trans Am and Rally.
RS 15 Grey
Very high torque compound. It combines a 20% higher friction value than the RS14 with a slightly increased pad wear. Needs finesse to avoid over braking the car. Good release characteristic. Although the RS15 has a very good modulation (controllability) it might have an excessive bite for some applications, as lightweight cars or cars with boosted brakes. Applications: NASCAR, CART, F3, Touring cars, GT cars, WSC, DP, Trans Am and Rally.
RS 19 Yellow
Best compound for endurance racing on the basis of the RS 14. A slight reduction of the friction value improves the modulation (controllability). Nevertheless, the friction value is enough for cars without power-assisted brake system and ensures comfortable low effort on the brake pedal. Constant temperatures up to 600°C (1.100°F) are possible. The combination of friction value, fading stability and low wear rates on pads and discs (rotors) realized with this pad compound is unmatched up to now. Due to its outstanding wear rate and driveability PAGID endurance materials are often used at sprint races as well. A multiple winner of Daytona 24h, Le Mans 24h, Sebring 12h, Spa 24 h, Nürburgring 24h, often with no pad change and usually no disc (rotor) change. Application: All endurance racing cars from group N (Speed-WC, Grand Am Cup) up to GT and Sport-Prototypes (Grand Am DP).
RS 29 Yellow
New endurance compound. This compound combines the outstanding wear rate of the RS19 with a slightly higher coefficient of friction and initial bite. Due to its outstanding wear rate and driveability PAGID endurance materials are often used at sprint races as well. Application: All endurance racing cars from group N (Speed-WC, Grand Am Cup) up to GT and Sport-Prototypes (Grand Am DP).
slippydiff said:
Whilst making enquires as to why this has happened, I was told the Porsche yellow pads I've had fitted are in fact Pagid RS19s.
Just to clarify again - whoever told you this is wrong. The pads you have may well be made by Pagid manufactured for Porsche but they are not RS19's - they are P90 compound - a (very good) fast road pad just painted yellow.
gfreeman said:
P90 is the standard OPC brake pads for the GT3.
From your description and photos all you have done is glaze the pads through insufficient heat generation.
As the car is a GT3 you would expect it to be fitted with fast road pads for road use wouldn't you??
Having to pootle round town will tend to glaze the pads and you have reprinted Pagids correct bedding in procedure, so all is not lost.
You have removed the glaze so all you have to do now is just bed them in again correctly and you will be fine. If they glaze again in the future (when they start growling a bit) just follow the bedding in procedure again to restore stopping power - no need to sand them off.
The brake pads are fine. If you take a look at a set that have been used heavily on track you will be shocked at the state of them - crazed all over and still going strong!
From your description and photos all you have done is glaze the pads through insufficient heat generation.
As the car is a GT3 you would expect it to be fitted with fast road pads for road use wouldn't you??
Having to pootle round town will tend to glaze the pads and you have reprinted Pagids correct bedding in procedure, so all is not lost.
You have removed the glaze so all you have to do now is just bed them in again correctly and you will be fine. If they glaze again in the future (when they start growling a bit) just follow the bedding in procedure again to restore stopping power - no need to sand them off.
The brake pads are fine. If you take a look at a set that have been used heavily on track you will be shocked at the state of them - crazed all over and still going strong!
Tim, despite having owned several other RS Porsches, I'd only ever replaced pads on one of the 964 RSs I'd owned (and latterly my MK1 GT3)
I suspect the default original Porsche pad for the MK 1 was either Jurid or Textar, both of which fall closer to a road pad than a track pad. hence I got away with my gentle bedding in process on the GT3.
I'm guessing that Porsche stung by the criticism of the MK1 brakes, went overboard with the disc and pad spec for the MK2 and thus the pad material is closer to the track use end of the spectrum.
JZM fitted the front brake set up when they did the geometry on the car, I am "reasonably" knowledgeable about most things mechanical and perhaps gave the impression that I was aware of what I was having fitted to the car and how to bed it in.
It would however of been helpful if they'd either bedded the pads in for me whilst on roadtest or asked me if I knew how to carry out the bedding in procedure before sending me on my way !
A couple of final questions : do I need to de-glaze the face of the discs too ?
The Pagid bedding in procedure refers to "recovery stops" what exactly is a recovery stop ?
Whilst I'm not suggesting I'd deviate from their method of bedding pads in, is it imperative that it is followed to the word ?
Many Thanks
Edited by slippydiff on Sunday 18th February 01:39
slippydiff you are right about the GT3 Mk1 pads - they were not a Pagid compound but having said that the next generation pads for the Mk2 were not really suited to heavy track use.
You shouldn't need to deglaze the pads if you follow the Pagid instructions as you should bust the glaze off with the first heavy stop.
A recovery stop puts heat in the brakes more gently than a heavy stop, bringing them gradually to a high working temperature. It is the procedure described in Step1.
There are many tried and tested bedding in methods used by people with better knowledge than me but I always try and stick to the Pagid instructions - just be carefull you don't go too mad and overheat the brakes by a lot of heavy stomping! The idea is to gradually build the temp before you stomp on them then gradully cool down....
maximu5 the year before last people were trying out all sorts of Pagid colours, gradually coming round to RS29's for the GT3, seems to really suit the alcon/brembo floaters. I would guess most GT3's use them now (well, I do!)although stateside seem to prefer the older version RS19's, and others seem to stick to their favourites.
Anyone else??? Ought to start a poll on trackday pads for 6 pot GT3's
You shouldn't need to deglaze the pads if you follow the Pagid instructions as you should bust the glaze off with the first heavy stop.
A recovery stop puts heat in the brakes more gently than a heavy stop, bringing them gradually to a high working temperature. It is the procedure described in Step1.
There are many tried and tested bedding in methods used by people with better knowledge than me but I always try and stick to the Pagid instructions - just be carefull you don't go too mad and overheat the brakes by a lot of heavy stomping! The idea is to gradually build the temp before you stomp on them then gradully cool down....
maximu5 the year before last people were trying out all sorts of Pagid colours, gradually coming round to RS29's for the GT3, seems to really suit the alcon/brembo floaters. I would guess most GT3's use them now (well, I do!)although stateside seem to prefer the older version RS19's, and others seem to stick to their favourites.
Anyone else??? Ought to start a poll on trackday pads for 6 pot GT3's
I think that I have posted this reply into outer space so, as a beginner, I will try again.
Mine and others experience of both steel & ceramic 997 GT3 brakes when used on circuits is the same. Horrible pedal and premature ALB. Could be glazed pads but mine were well and truely bedded so I tend to discount that but it is interesting to note that the only happy 997 GT3 user was in an RS. Difficult to know what that means because I have no idea of this guy's experience or personal (braking) taste.
I have spoken to Pagid and if all else fails I will buy from them although I(we)feel that it shouldn't be necessary on this type of vehicle.
Any other input would be greatfully received
Mine and others experience of both steel & ceramic 997 GT3 brakes when used on circuits is the same. Horrible pedal and premature ALB. Could be glazed pads but mine were well and truely bedded so I tend to discount that but it is interesting to note that the only happy 997 GT3 user was in an RS. Difficult to know what that means because I have no idea of this guy's experience or personal (braking) taste.
I have spoken to Pagid and if all else fails I will buy from them although I(we)feel that it shouldn't be necessary on this type of vehicle.
Any other input would be greatfully received
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