Alcon Brake issues - please look

NZ_M3 · 03-03-2010, 09:33 AM

Mods, if you don't mind leaving this up for a short while here - I understand that it should really belong to the technical forum, but I want to gather as much feedback as I can in as short of space of time as possible.

Ladies and Gents I need your help !! (John (Thorney), if you can give me your input also it would be great, as I am sure you'd probably have some clue as to what might be going on???)

Okay for those of you that run Alcon Brakes or have run them (especially those doing CSL Cups with these brakes, or a variant of it) - I've been having some issues lately with these brakes and I can't seem to get to the bottom of it:

Quick background:

This is the second set of rotors I've put on - the first set warped after 3 track outings - this was really partially my fault as I didn't bother to bed the rotors in

(got too excited about new brakes and pretty much just drove them to death) - they would have lasted less than 1000km of driving.

My recent track day just been I bedded the brakes in religiously. I did: 10 sets of mid speed near stops (i.e. less than 100km/h) to bring the temperature up, then had the brakes cool down completely (combination of cool down laps where very little brakes were applied and afterwards letting the car cool down completely for about 20 minutes)

This was followed by 2 more sets of 10 high speed stops (near race speed 180km/h to 220km/h) with cool down laps in between the 2 sets, followed by a 30 minute cool down.

During the cool down periods I made sure that the car didn not stay stationary in one spot and rolled the car back and forth multiple times to prevent heat soak.

Afterwards I went about my normal track day, each time keeping the fast laps to a maximum of 4 laps (2.2km course) followed by 2 cool down laps each time.

As the day went by I could feel that awful juddering sensation that you get when the discs are warped - it got worse the hotter the brakes ran ... HOWEVER - each time this started to rear its ugly head I would slow down the pace and give the brakes plenty of opportunity to cool down, as the brakes cooled the juddering went away, but would come back again as the brakes heated up.

by the afternoon sessions I could only get in about 2 and a half laps of the 2.2km circuit before the juddering came back (it certainly wasn't fun as the steering wheel shook away in my hand under hard braking).

On this circuit there's 2 heavy stops (1x220km/h and the other about 250km/h braking) - that's about it and each time the juddering came, it would happen at all the braking points, even the ones where I am simply tapping the brakes to scrub speed.

Lucky for me the discs don't seem to be warped - as from stone cold I can be applying the brakes lightly or really heavily and there would be no juddering or shake of the steering wheel - it would be perfect stop every time. However once hot it would appear again.

I tried holding the brakes whilst accelerating and I could feel as the brakes got hotter the steering started to shake ...

Once cooled down, everything went back to normal.

Now Question!!

1. Are my brakes simply overheating?

2. Are my discs not 'floating' properly against the bell causing it to warp as it got hot?

3. Something else causing the juddering feel?

PS> The car has had new front control arm bushing put it and all the front ball joints checked - there doesn't appear to be anything steering related - plus when the car is stone cold it'd stop perfectly and with loads of stopping power.

PS2> I also have no brake cooling of any sort whatsoever on this car ... probably a mistake - also the backing plates are still in place.

PS3> This is doing my head in so much that I am even considering going back to the stock brake set up!!!

ANY INPUT, OPINIONS, THEORIES APPRECIATED!!

Some pictures of the discs

Passenger side:

Driver side:

03-03-2010, 09:33 AM	#1
NZ_M3 S5, Sport On, DSC M-track Join Date: Jun 2008 Location: Auckland, New Zealand Posts: 1,434 Casino cash: $13579	Alcon Brake issues - please look Mods, if you don't mind leaving this up for a short while here - I understand that it should really belong to the technical forum, but I want to gather as much feedback as I can in as short of space of time as possible. Ladies and Gents I need your help !! (John (Thorney), if you can give me your input also it would be great, as I am sure you'd probably have some clue as to what might be going on???) Okay for those of you that run Alcon Brakes or have run them (especially those doing CSL Cups with these brakes, or a variant of it) - I've been having some issues lately with these brakes and I can't seem to get to the bottom of it: Quick background: This is the second set of rotors I've put on - the first set warped after 3 track outings - this was really partially my fault as I didn't bother to bed the rotors in (got too excited about new brakes and pretty much just drove them to death) - they would have lasted less than 1000km of driving. My recent track day just been I bedded the brakes in religiously. I did: 10 sets of mid speed near stops (i.e. less than 100km/h) to bring the temperature up, then had the brakes cool down completely (combination of cool down laps where very little brakes were applied and afterwards letting the car cool down completely for about 20 minutes) This was followed by 2 more sets of 10 high speed stops (near race speed 180km/h to 220km/h) with cool down laps in between the 2 sets, followed by a 30 minute cool down. During the cool down periods I made sure that the car didn not stay stationary in one spot and rolled the car back and forth multiple times to prevent heat soak. Afterwards I went about my normal track day, each time keeping the fast laps to a maximum of 4 laps (2.2km course) followed by 2 cool down laps each time. As the day went by I could feel that awful juddering sensation that you get when the discs are warped - it got worse the hotter the brakes ran ... HOWEVER - each time this started to rear its ugly head I would slow down the pace and give the brakes plenty of opportunity to cool down, as the brakes cooled the juddering went away, but would come back again as the brakes heated up. by the afternoon sessions I could only get in about 2 and a half laps of the 2.2km circuit before the juddering came back (it certainly wasn't fun as the steering wheel shook away in my hand under hard braking). On this circuit there's 2 heavy stops (1x220km/h and the other about 250km/h braking) - that's about it and each time the juddering came, it would happen at all the braking points, even the ones where I am simply tapping the brakes to scrub speed. Lucky for me the discs don't seem to be warped - as from stone cold I can be applying the brakes lightly or really heavily and there would be no juddering or shake of the steering wheel - it would be perfect stop every time. However once hot it would appear again. I tried holding the brakes whilst accelerating and I could feel as the brakes got hotter the steering started to shake ... Once cooled down, everything went back to normal. Now Question!! 1. Are my brakes simply overheating? 2. Are my discs not 'floating' properly against the bell causing it to warp as it got hot? 3. Something else causing the juddering feel? PS> The car has had new front control arm bushing put it and all the front ball joints checked - there doesn't appear to be anything steering related - plus when the car is stone cold it'd stop perfectly and with loads of stopping power. PS2> I also have no brake cooling of any sort whatsoever on this car ... probably a mistake - also the backing plates are still in place. PS3> This is doing my head in so much that I am even considering going back to the stock brake set up!!! ANY INPUT, OPINIONS, THEORIES APPRECIATED!! Some pictures of the discs Passenger side: Driver side: Last edited by NZ_M3; 03-03-2010 at 09:57 AM.