Alcon Brake issues - please look

[NZ_M3]

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:

[shimmy]

what pads are you using?

[NZ_M3]

Originally Posted by shimmy

what pads are you using?

Ferodo Racing DS3000

[DazBlackCSL]

Must admit having run AP's on road car, and raced on Alcon's in the CSL cup this seems to be a feature of the Alcons, had a mate who had the Alcons on and they were always juddering on track days and the ring.

That being said I think you have to drive through it as they do improve, did not have the same issues on the race car, but then as Shim says might be the pads that can really make a difference.

Although not had issues with AP's running RS29's at all

Your discs look fine as well.

Im not the most technical of people!! tend to just get in and drive lol

[shimmy]

ive had AP issues in the past running DS2500 (couple of sets of rotors)

could have been me and also the pads

i would have thought DS3000 far better as full race pads (but they will ruin your rims)

[NZ_M3]

Originally Posted by DazBlackCSL

Must admit having run AP's on road car, and raced on Alcon's in the CSL cup this seems to be a feature of the Alcons, had a mate who had the Alcons on and they were always juddering on track days and the ring.

That being said I think you have to drive through it as they do improve, did not have the same issues on the race car, but then as Shim says might be the pads that can really make a difference.

Although not had issues with AP's running RS29's at all

Your discs look fine as well.

Im not the most technical of people!! tend to just get in and drive lol

Oh interesting that your mate's also experienced this !!!... was it also on a CSL or M3? So it improves as it wore in?

I also have a set of SBS road pads, but from memory those are lot worse and hardly any better than factory in terms of stopping power.

I did think the discs looked fine (unlike my warped set .. that disc is no longer round .. it's a bit oval )

Originally Posted by shimmy

ive had AP issues in the past running DS2500 (couple of sets of rotors)

could have been me and also the pads

i would have thought DS3000 far better as full race pads (but they will ruin your rims)

So you had similar sort of issues with DS2500 on th APs Shim??

I regret using the Ferodos after a couple of track days now to be honest ... wish I had gone to Pagids, Performance Friction or Endless ...

[_Nathan_]

My initial thought was pad deposits but DS3000 are hard, sintered pads and should be up to the job.

I'd be tempted to try some PF01s or RS29s though to see if it made a difference.

[shimmy]

i think DS2500 are essentially road pads and cant cope with the heat created at the front of the e46 - ds3000 are much harder, full of iron

when you say OVAL are they noticably warped or could it be pad deposits

[NZ_M3]

Originally Posted by _Nathan_

My initial thought was pad deposits but DS3000 are hard, sintered pads and should be up to the job.

I'd be tempted to try some PF01s or RS29s though to see if it made a difference.

Might pay to try some other pads I think ... because this new disc set certainly don't look or feel warped to me ...

Originally Posted by shimmy

i think DS2500 are essentially road pads and cant cope with the heat created at the front of the e46 - ds3000 are much harder, full of iron

when you say OVAL are they noticably warped or could it be pad deposits

the warped set is oval - in the sense that if you stand it up next to the new disc it is noticeably taller one way and shorter the other

hmmm the common denominator so fars seems to be pointing to a pad issue ... I really do hope so - don't really want to be buying new discs every couple of trackdays - it can get a bit expensive I think

[glendog74]

Originally Posted by shimmy

ive had AP issues in the past running DS2500 (couple of sets of rotors)

could have been me and also the pads

I had judder on my APs using DS2500 on track - especially when trail braking.

The issue went away with Pagid RS29s