ALCON Brake Judder

[Bus Driver]

Hi all,

I have this judder problem with my Alcon 365mm 6 pot BBK on DS performance pads. After about 2k kms on it, I took it to the Sepang F1 circuit. First 2 laps was a warm up lap, then on the 3rd lap i started pushing it a bit hard and it started to judder during braking and I didn't continue further. When cool and normal driving all was ok but after multiple medium braking the judder is back. Drove for a few hundred kilometers before I took it to the mechanic.

After careful inspection it was found that the brake wear was tapered ( how do I post pictures here?) Using a dial gauge, mechanics confirmed the rotors were warped ( is it so easy to warp these rotors?) so had them skimmed and bought new Pagid RS29 pads.

Bed them in as per the instructions from Pagid. Now at about 100-110kmh it starts to judder again with even light braking ..when pressed harder the judder is less. Also after a couple of medium braking, the steering starts vibrating even without any brake inputs...I've already had the wheels balanced and rotated front to back. I'm not keen on skimming the discs further..any other ideas what is causing this? Hope you guys can help out.
Regards

[westwest888]

I had this same exact problem. It's your pads. Ferodo makes real crap - that's why those pads come for free with every BBK.

* The first rule of big brake kits is DO NOT use the free pads
* The second rule of big brake kits is DO NOT use the free pads

Buy a proper set of Pagid Yellow or Performance Friction pads. It should cost you about $350 per axle.

What's happening is the pad is expanding under heat and causing brake shudder. Once the pad cools down you are able to drive normally again. I really can't believe they sell these. It's like nobody has QA'd them.

Also, the BBK calipers should always produce even pad wear. You can know with good certainty that the inside pad wear should be the same as the outside.

[Bus Driver]

Thanks for the reply West..I'm now on Pagid RS29 after skimming the discs and the vibration is still there..and it remains even after the brakes are released, already balanced the rims/tires too... Also what do you think could have caused the tapered pad wear..I'm trying to rule out other possibilities before getting new discs from Alcon..

[13S4]

( how do I post pictures here?)

http://www.audizine.com/forum/showth...es-in-a-thread

[westwest888]

I was able to just buff the discs with some fine wire mesh on a drill head, remove the old pad material, and bed the Pagids. Everything has been fine since.

[Bus Driver]

I guess there's some other problem causing this vibration since I've already skimmed the surface of the discs at one of the engineering shops using machinery..thanks West

[Jared@DriveSPM]

Bus Driver -

I don't post here often, but I am very, very familiar with the Alcon brake set-ups. I work closely with the top guy at Alcon in the U.S on a weekly basis - I have too many miles to remember on track and street with various pad compounds on the Alcon brakes.

Allow me to adress the issues you are experiencing.

First - Uneven pad wear
The comment above is false - The caliper will not alway provide even pad wear.
Take into consideration the track you were driving, and your personal driving style. Let's use an example - Let's say the track had mostly right hand turns, and you trail brake...The dynamic loading that transfers from the wheel to the upright will be amplified on the inside of the outside wheel - Thus, you will see more pad wear on the inside versus the outside pad. This is just a very simplistic example.

Brake judder -
Did you drive this kit daily prior to taking to Sepang?
If you drive these daily, depending on driving conditions, it is important to re-bed your pads in every few months.
High spots are created on the rotor face (wear annulus) from daily driving (after so many miles) ; if you don't re-bed your pads to get rid of the high spots and lay down a fresh transfer layer (following Alcon's bed-in instructions carefully) your pad will start riding on these high spots of pad build -up...This can cause a vibration, and can also create hot spots in the rotor. These hot spots (depending on the severity) penetrate deep into the rotor wall, and will not be removed during a grinding operation...
I suspect you have hotspots - The reason being, after grinding the rotor, you noticed a temporary improvement which is due to the old pad layer being removed...But came back.

Alcon crescent groves - Have you cleaned the pad material from your crescent grooves? Pad material will build-up in the grooves and creates judder due to inefficient gas release.

Lastly - Do not be afraid of using the DS Performance pads. Ferodo makes a great quality product, they also make a pad that is more suitable for spirited driving such as the DS2500 and DS3000.

I hope I have adressed everything you wrote about, please feel free to send me a PM if you have any questions, I will be happy to take care of them.

Thank you

Jared E

[Bus Driver]

Hi Jared,much appreciated for the explanation..you have PM

[westwest888]

FWIW that Ferodo pad didn't work for me on an AP Racing BBK and exhibited the same behavior.

I meant that the inside pad and the outside pad should wear evenly. It could wear on an angle.

[Bus Driver]

FWIW that Ferodo pad didn't work for me on an AP Racing BBK and exhibited the same behavior.

I meant that the inside pad and the outside pad should wear evenly. It could wear on an angle.

Cheers for the info..anyhow here's some pictures..thanks to 13S4 for the link on how to post a picture!


IMAG0160 by BusDriver330, on Flickr



IMAG0162 by BusDriver330, on Flickr


These are after skimming with new pagid pads, just took them 5 mins ago,first one a bit too bright on the flash reflection:


IMAG0175 by BusDriver330, on Flickr



IMAG0172 by BusDriver330, on Flickr

[Chestlock]

What's the easiest way to clean pad material out of the grooves?

[A4 Centaur]

Those pads are shot. Ferodo makes good MC pads I have used them for years. However, westwest888 is correct. Get proper Race Pads to use at the track. It is a hassle, but you need to swap your pads out when you take your car to the track. I do it with my bikes and it is a pretty straight forward process, that way you won't destroy the street compound pads. Street pads are designed for the street. You car is heavy and destroying those pads. Be safe!

[Bus Driver]

The last picture are the new Pagid RS29 track pads that I just put on after skimming the disc ...

[aaron1085]

I see Jared's point, but as I've posted before, I have had a continued issue like this. I run the StaSiS street pads on the street and the track pads on the track. I had to re-surface the Mono4 Alcon BBK after 2,000 miles and a few track days which improved low speed judder, however it persists during 25-10mph braking. This is not acceptable for a $3000 kit.

[Bus Driver]

I see Jared's point, but as I've posted before, I have had a continued issue like this. I run the StaSiS street pads on the street and the track pads on the track. I had to re-surface the Mono4 Alcon BBK after 2,000 miles and a few track days which improved low speed judder, however it persists during 25-10mph braking. This is not acceptable for a $3000 kit.

So do you think it's the discs or other components? was thinking of getting other brand replacement discs...in case i cant sort this out..it's really frustrating after paying so much on them..furthermore I'm now on new pads.

[Jared@DriveSPM]

I actually just use a pick to clean out the crescent grooves...Doesn't have to be anything special, just a little time consuming!

Another point - As others have already said, obviously a great idea to use a dedicated pad for the track and one for the street...You should however make sure the pad compounds are compatible with one another. Better to stick with one brand and use two models of pad rather than trying to use brand A for track and brand B for the street.

That's been my experience,

[Jared@DriveSPM]

sorry - double post

[aaron1085]

So do you think it's the discs or other components? was thinking of getting other brand replacement discs...in case i cant sort this out..it's really frustrating after paying so much on them..furthermore I'm now on new pads.

I don't know, but I can assure you I'm not using a pick to clean each little groove on my rotors; again...rediculous for a $3,000 kit. I use the StaSiS street AND track pads so that there is no confusion of compounds working together, etc.

I'm not sure what the final issue is. The pads seem to be wearing properly, so I don't feel the calipers being the issue, I think the rotors are just sensitive or something, but I'm not as impressed.

[Jared@DriveSPM]

Just sharing my experience, I've had to clean the crescents on my $8,000 front/rear kit for the E46. Something that comes with the territory when you step up to big boy brakes. There is a certain amount of added maintenance required...

I would suggest contacting their technical support for further assistance if needed.

[aaron1085]

Ok Jared, I'll bite....lets see the $8000 brakes, those must literally be a work of art!

I get it, more maintenance, more cost, etc....however, I expect maintenance in the form of replacing pads , not cleaning them every month with a toothpick. I daily drive the brake kit, and then track it all summer long. I just want smooth,even braking.

I contact stasis when I first resurfaced the rotors. I just got the response of "check the caliper alignment, etc". Which is fine, that is what I did, but as stated, I feel the problem persists slightly and can't figure out why. Any direct contact you have over there Jared?

[Bus Driver]

Ok guys, some updates.. had the hubs cleaned from any rust and brakes reinstalled, rebedded ..had the rims checked again, there's some dent in front so moved them to the rears, tyres rebalanced..drove the car from cold and steering still vibrates at 100-120kmh.. according to the tire shop, the dented rims even though positioned to the back are causing this since our cars are quattro ( really??)
I've read some guys A4/S4 with 2009 models had this problems and the cause was the lower cross arm and bushing, Audi had TSB...but mine is 2010 model..
I don't want to skim the discs again...any other possible causes? some say the discs was not properly skimmed..could a warped disc or Disc thickness Variation cause the steering to vibrate only at certain speeds?

[Gweezil]

I am experiencing this same judder with my 370mm Alcom front setup. I also have significant brake dust buildup on the front wheels, even with regular washing by hand. I am convinced that I need a different set of pads. I'll try cleaning the slots (Really??) but never was given any info on how to properly bed pads. Anyone have a link to that? Thanks for any help.

[Brooklyn]

important lesson learned here for me...the hell with cleaning out rotors with fricking toothpicks after dropping $3k plus. big boy rules for big boy brakes? seriously? has alcon provided any guidance to any of you guys experiencing this issue? that's ridiculous.

[Bus Driver]

I am experiencing this same judder with my 370mm Alcom front setup. I also have significant brake dust buildup on the front wheels, even with regular washing by hand. I am convinced that I need a different set of pads. I'll try cleaning the slots (Really??) but never was given any info on how to properly bed pads. Anyone have a link to that? Thanks for any help.

Here's the link from Alcon UK website http://www.alcon.co.uk/brake-kits/br...nd-tricks.html
..click on the tips and tricks. Different pads will have different ways of bedding in..race pads have a more vigorous bedding in procedure. I have switch to the Pagid RS29 yellow pads..couldnt be happier..no squeal at all..works from cold and has great initial bite.
As for the judder I experienced...it is almost completely gone after almost 1000kms..I'm convinced the discs are not warped..just due to the DTV (disc thickness variation) from the lousy stock DS pads that came with the kit..

[Gweezil]

Here's the link from Alcon UK website http://www.alcon.co.uk/brake-kits/br...nd-tricks.html
..click on the tips and tricks. Different pads will have different ways of bedding in..race pads have a more vigorous bedding in procedure. I have switch to the Pagid RS29 yellow pads..couldnt be happier..no squeal at all..works from cold and has great initial bite.
As for the judder I experienced...it is almost completely gone after almost 1000kms..I'm convinced the discs are not warped..just due to the DTV (disc thickness variation) from the lousy stock DS pads that came with the kit..

Thanks for the link. Any reduction in brake dust with the pagids?

[Bus Driver]

Funny you asked..reprayed my RS4 wheels to dark gunmetal so didnt notice..just changed to Breyton BE GT-AV brilliant silver yesterday..will update you soon on the brake dusts!

[Liquidsystm]

Posted this in the A4 B8 Forum, but no one over there is really running these brakes:

Went to NCRC Thunderhill event over the weekend and ran the Bypass instead of the Cyclone, but still fun nonetheless. Finally had the chance to test out the new Alcon/Stasis 370mm kit, but didn't have a chance to buy proper track pads in time for this event, so I ran the shitty Stasis/project mu ones it came with. As warned by QUA77RO, these pads are worthless and I did encounter a problem with the pads as they got hot after a few laps. Also, this was my first time running with a new motor since my last one blew, which was warrantied by Audi, so currently the motor is completely stock with no tune. Can't wait to get proper pads and hit the track again, but here are a few pics.





As the brakes got hot, something was expanding and the right side pad was being pushed into the top hat of the rotor and rubbing away at it. You can see where it rubbed away, above the bolts of the top hat, you see bare metal, where it should be black. As i would come off the track, it would make a clunk clunk noise, and I would have to push the pad back in towards the calipers and away from the touching the rotor hat. The problem would go away as the brakes cooled off.

[*Blue-Angel*]

Wouldnt of happened with a proper floating brake set up. Although you wouldnt want to drive a set up like that on the street as it would clunk quite bad over rough roads like brick. Interesting to see their was enough time to rub the rotor bell but not the rust ring from the unswept area of the ID of the rotor ring. The pad backing plate came in contact with the mounting bell.

[MARIUS24]

Hello , i nave the same judder problem with my alcon bbk 6 pot 365 mm , i have them on my Audi A5 3.0 TDI
Can you please tell me what pads i have to buy , i need a serial code of the pads..

[Jeff@RevoUSA]

If the vibration has just started, the chances are that the temperature has never reached the point where cementite begins to form. In this case, simply fitting a set of good "semi-metallic" pads and using them hard (after bedding) may well remove the deposits and restore the system to normal operation but with upgraded pads. If only a small amount of material has been transferred i.e. if the vibration is just starting, vigorous scrubbing with garnet paper may remove the deposit. As many deposits are not visible, scrub the entire friction surfaces thoroughly. Do not use regular sand paper or emery cloth as the aluminum oxide abrasive material will permeate the cast iron surface and make the condition worse. Do not bead blast or sand blast the discs for the same reason.

Another option is to run Hawk Blue pads, they are effective in removing uneven pad deposits from rotors. Other higher temperature performance pads may also effectively “scrub” off uneven pad deposits.

Regards,

[Jeff@RevoUSA]

Posted this in the A4 B8 Forum, but no one over there is really running these brakes:

Went to NCRC Thunderhill event over the weekend and ran the Bypass instead of the Cyclone, but still fun nonetheless. Finally had the chance to test out the new Alcon/Stasis 370mm kit, but didn't have a chance to buy proper track pads in time for this event, so I ran the shitty Stasis/project mu ones it came with. As warned by QUA77RO, these pads are worthless and I did encounter a problem with the pads as they got hot after a few laps. Also, this was my first time running with a new motor since my last one blew, which was warrantied by Audi, so currently the motor is completely stock with no tune. Can't wait to get proper pads and hit the track again, but here are a few pics.





As the brakes got hot, something was expanding and the right side pad was being pushed into the top hat of the rotor and rubbing away at it. You can see where it rubbed away, above the bolts of the top hat, you see bare metal, where it should be black. As i would come off the track, it would make a clunk clunk noise, and I would have to push the pad back in towards the calipers and away from the touching the rotor hat. The problem would go away as the brakes cooled off.

Excuse my late appearance - Did you ever get this resolved?

I would like to add clarity to your statement "so I ran the shitty Stasis/project mu ones it came with". Pad choice is key!

Choosing the correct brake pad starts with an honest assessment of the driver's typical driving conditions. For example, if the vehicle is driven 80 percent in highway and 20 percent sporty and zero percent on the track, then an "street" pad will likely offer the best combination of stopping performance, low dust and low noise.
If the vehicle is frequently used for track days but also as a daily driver, it might be better served by the a mid-range racing pad - provided that an even transfer layer of pad material on the rotor is maintained by periodically re-bedding in the pads.

[MARIUS24]

Hello :) thank's for the info
My car is all day drive , but around 160-200 km/h when i use the brake , the car just start to jugger and vibrate , it's a scarry felling :( and the brake pad is getting soft .....
Today i took them of and install the OEM brake kit
Insend the discs to be resurfeced and clean
My alcon caliper code is : F97ZG02-24F7AL 6 pot Discs have 365 mm
Can you please give me a part code for the pads , it's hard to find them in România :P

Excuse my english :P

[Mops@Nemesis]

http://www.audizine.com/classifieds/...ing-bbk&cat=78

Killer kit! Just sayin'...

[Bus Driver]

Hello :) thank's for the info
My car is all day drive , but around 160-200 km/h when i use the brake , the car just start to jugger and vibrate , it's a scarry felling :( and the brake pad is getting soft .....
Today i took them of and install the OEM brake kit
Insend the discs to be resurfeced and clean
My alcon caliper code is : F97ZG02-24F7AL 6 pot Discs have 365 mm
Can you please give me a part code for the pads , it's hard to find them in România :P

Excuse my english :P

You can try jdlbrakes.com They're one of the biggest Alcon suppliers in europe..look up Daniel..He'll get you the right pads..if you don't mind brake dust, I recommend the Pagid RS 29 yellow pads.

[Jeff@RevoUSA]

Hello :) thank's for the info
My car is all day drive , but around 160-200 km/h when i use the brake , the car just start to jugger and vibrate , it's a scarry felling :( and the brake pad is getting soft .....
Today i took them of and install the OEM brake kit
Insend the discs to be resurfeced and clean
My alcon caliper code is : F97ZG02-24F7AL 6 pot Discs have 365 mm
Can you please give me a part code for the pads , it's hard to find them in România :P

Excuse my english :P

This is an Alcon Advatage Extreme kit, not a STaSIS kit. In the case, you can source pads from Carbotech, PMU, Pagid, etc. - Just let them know you have an Alcon mono6 caliper.

[Mops@Nemesis]

Funny, I just found out yesteday, that Carbotech in only about 70 miles from me. Very excited about that.