Not joined yet? Register for free and enjoy features such as alerts, private messaging and viewing latest posts and topics.

CSL disc disintegrating??

"M" Specific discussion
Lower
Member
Member
Posts: 352
Joined: Sat Feb 26, 2011 11:16 pm

CSL disc disintegrating??

Post by Lower » Tue Sep 15, 2020 12:01 pm

Pbondar wrote: Mon Sep 14, 2020 5:11 pm Seems like pretty straightforward galling caused by using a stainless steel disc and aggressive (their words) incomparable pad..

https://www.bssa.org.uk/topics.php?article=12 Refers
I've never heard of car brake discs being made of stainless steel. If they are, they are certainly not up to the job.

I think they are just poor quality discs.
57 Z4MC Interlagos blue, Champagne leather, Carbon Dash, SatNav, Bluetooth, Cruise Control, Logic 7, Heated Seats, Rear Park sensors, Isofix and airbag disable switch for the ideal family car :)
Now Sold and replaced with a M2

Pbondar

CSL disc disintegrating??

Post by Pbondar » Tue Sep 15, 2020 12:17 pm

Lower wrote: Tue Sep 15, 2020 12:01 pm
Pbondar wrote: Mon Sep 14, 2020 5:11 pm Seems like pretty straightforward galling caused by using a stainless steel disc and aggressive (their words) incomparable pad..

https://www.bssa.org.uk/topics.php?article=12 Refers
I've never heard of car brake discs being made of stainless steel. If they are, they are certainly not up to the job.

I think they are just poor quality discs.
If you look at the picture, it doesn't seem to me to be the usual cast iron disc..lack of corrosion seems to indicate a different materal?

User avatar
buzyg
Legend
Legend
Posts: 26421
Joined: Fri May 20, 2011 6:11 pm
Location: Cornwall

CSL disc disintegrating??

Post by buzyg » Tue Sep 15, 2020 1:28 pm

Pbondar wrote: Mon Sep 14, 2020 5:11 pm Seems like pretty straightforward galling caused by using a stainless steel disc and aggressive (their words) incomparable pad..

https://www.bssa.org.uk/topics.php?article=12 Refers
Tend to agree with this prognosis. Though I didn't realise you could get stainless discs for the Z4 before I saw this. :?

Looks like plenty left in them so a skim would recover the surface.

Then softer pads for normal road use.

But if they are stainless, then heavy road / track work is going to do the same thing again. :(
Image

User avatar
RedUn
Senior Member
Senior Member
Posts: 1102
Joined: Sat Jun 16, 2012 7:33 pm
Location: Hertfordshire

CSL disc disintegrating??

Post by RedUn » Thu Sep 17, 2020 7:14 pm

z4mcc wrote: Mon Sep 14, 2020 9:28 pm I’ve ran rc5/6 on various cars including m cars without issue.

I’ve ordered some proper bmw discs from cotswolds (cheapest in the end) and will see how they hold up.
If you don't change the pads change the cooling setup, have you the ducts in the bumper open?

Some oem discs (if yours aren't oem? ) could be better quality but they will still get to roughly the same temperature as your current discs assuming they are similar mass and design.

You either need bigger thicker discs that can take more heat or more cooling or different pads or all three :thumbsup: :driving:
IMOLA Z4///MR

User avatar
BMWZ4MC
Lifer
Lifer
Posts: 6337
Joined: Sun Sep 13, 2009 4:24 pm
Location: Back in the sunshine

CSL disc disintegrating??

Post by BMWZ4MC » Thu Sep 17, 2020 8:57 pm

I don’t think this is a consequence of overheating. I ran OEM discs on my car for about eight years, during which I covered thousands of miles on track using progressively more aggressive brake pads with each pad change. On numerous occasions I’ve seen pads smoking even after cool down laps and I’ve even had the friction surface of the pads break up through over heating. I’ve also seen OEM discs crack from heat stress (albeit not mine). However, I’ve never seen a disc that looks like that.
I suspect these discs are cheap copies of the OEM discs and they are not fit for purpose. The pad choice is probably irrelevant.
Image
Z4MC - heavily fettled for track use
Lotus Exige - sensible daily driver on the mods slippery slope
Westfield SEiW - in hibernation
Modified RS4 Avant - back in Blighty
S2000 GT - gone

Online
User avatar
Nictrix
Lifer
Lifer
Posts: 5423
Joined: Mon Aug 18, 2014 9:59 pm
Location: Paisley

CSL disc disintegrating??

Post by Nictrix » Thu Sep 17, 2020 9:59 pm

Pbondar wrote: Tue Sep 15, 2020 12:17 pm
Lower wrote: Tue Sep 15, 2020 12:01 pm
Pbondar wrote: Mon Sep 14, 2020 5:11 pm Seems like pretty straightforward galling caused by using a stainless steel disc and aggressive (their words) incomparable pad..

https://www.bssa.org.uk/topics.php?article=12 Refers
I've never heard of car brake discs being made of stainless steel. If they are, they are certainly not up to the job.

I think they are just poor quality discs.
If you look at the picture, it doesn't seem to me to be the usual cast iron disc..lack of corrosion seems to indicate a different materal?
I have seen markings like this before on bike discs where most of these are stainless as far as I know.
E89 2014 35i M Sport Black with Black leather :)

User avatar
RedUn
Senior Member
Senior Member
Posts: 1102
Joined: Sat Jun 16, 2012 7:33 pm
Location: Hertfordshire

CSL disc disintegrating??

Post by RedUn » Thu Sep 17, 2020 11:14 pm

Them discs, original or not, are not stainless, you can see the casting marks in the holes, they have internal venting, it's impossible to machine that. They are cast iron.

The brake pads also have a high iron content, now think about it, what's likely to break down under high temperature and pressure, the 20kg cast disc or the 200gram pad that can't dissipate the heat.

I used similar (hugely recommended etc etc) high iron content pads in the past on oem discs on another car and my discs cracked in half. Tried uprated discs etc etc in the end, different pads solved it and the braking was better and more consistent. Some pads just generate much more heat than others with similar performance, once they get hot the braking force drops off and you end up killing the discs.
IMOLA Z4///MR

z4mcc
Newbie
Newbie
Posts: 44
Joined: Wed Nov 07, 2018 10:51 am

CSL disc disintegrating??

Post by z4mcc » Mon Nov 01, 2021 11:14 pm

Update: exactly the same has happened on oem discs. Front and rear running rc5+ after 3 or so track days.

Braking performance was excellent except towards the end of the stint on only very deep into the pedal.

Running cup2’s

Not tried the skim yet but will get all 8 done most likely as the price of new is madness for 3 track days.

The pads are barely worn which is incredible as I was getting through yellow stuffs in a single day and these must be on 8.

After a skim I’ll go with a much softer pad and possible some direct to disc cooling ducts or at least remove the heat shields.

Such a strange problem. I personally feel it is the pads but a swap will see. I might try the ebc race pad or blue stuff. Or maybe ds2500

User avatar
AndyBeech
Senior Member
Senior Member
Posts: 1623
Joined: Mon Feb 18, 2013 2:25 pm
Location: Reading / Bath

CSL disc disintegrating??

Post by AndyBeech » Tue Nov 02, 2021 12:25 am

z4mcc wrote: Mon Nov 01, 2021 11:14 pm Update: exactly the same has happened on oem discs. Front and rear running rc5+ after 3 or so track days.

Braking performance was excellent except towards the end of the stint on only very deep into the pedal.

Running cup2’s

Not tried the skim yet but will get all 8 done most likely as the price of new is madness for 3 track days.

The pads are barely worn which is incredible as I was getting through yellow stuffs in a single day and these must be on 8.

After a skim I’ll go with a much softer pad and possible some direct to disc cooling ducts or at least remove the heat shields.

Such a strange problem. I personally feel it is the pads but a swap will see. I might try the ebc race pad or blue stuff. Or maybe ds2500
Ouch! Depending how many track days you do a year I'd consider a BBK. Doesn't have to be crazy expensive. I've used K Sport fronts and OEM setup rears on 8 track days this year. Pagid RSL-29 pads, still got life in both front and rear and discs are also fine apart from some crazing on the front discs which is to be expected. Almost zero fade in 30 odd minute sessions, basically a fit and forget set up. Fine to use on the road also.
I'd be surprised if I didn't get another 4-5 track days out of the pads next year and same with the discs. I'd consider it personally, OEM setup could be a false economy depending how many days you do.
Z4MR - Gruppe M, Bilstein PSS10, CSL's + 18" CSL reps with semi's, RTAB Limiters, Powerflex’d, PF Camber Arms, K-Sport BBK / RSL-29, GC Camber Plates, Strut Brace, Exhaust valves, custom brake cooling, complete underside refresh!

mmm-five
Lifer
Lifer
Posts: 12714
Joined: Sun Nov 30, 2008 1:03 pm
Location: Liverpool
Contact:

CSL disc disintegrating??

Post by mmm-five » Tue Nov 02, 2021 3:36 pm

z4mcc wrote: Mon Nov 01, 2021 11:14 pm Update: exactly the same has happened on oem discs. Front and rear running rc5+ after 3 or so track days.

Braking performance was excellent except towards the end of the stint on only very deep into the pedal.

Running cup2’s

Not tried the skim yet but will get all 8 done most likely as the price of new is madness for 3 track days.

The pads are barely worn which is incredible as I was getting through yellow stuffs in a single day and these must be on 8.

After a skim I’ll go with a much softer pad and possible some direct to disc cooling ducts or at least remove the heat shields.

Such a strange problem. I personally feel it is the pads but a swap will see. I might try the ebc race pad or blue stuff. Or maybe ds2500
Were you getting the same issue with Yellowstuff pads? If not, it seems to imply the high metal RC6/RC5pads are not suitable.
Trigger’s Z4MC
Some bits now over 163,000 miles, some less than 1,000 miles.
Individual Ruby Black, Individual extended champagne leather, plus many options

Image

brillomaster
Senior Member
Senior Member
Posts: 1423
Joined: Thu Aug 24, 2017 12:57 pm
Location: Leamington Spa

CSL disc disintegrating??

Post by brillomaster » Tue Nov 02, 2021 9:22 pm

I quite like performance friction 08 compound pads on my z4... easily did 8 full trackdays with excellent stopping power, and no sign they were eating the discs.

How long a session do you normally do on track?

User avatar
philipw
Member
Member
Posts: 150
Joined: Sat Apr 11, 2015 6:21 pm
Location: Bristol

CSL disc disintegrating??

Post by philipw » Tue Nov 02, 2021 9:44 pm

Agree with Andy, I am using RSL29 with Brembo 4pots and stock rear calipers. Zero issues with brake disc damage or fade and brake pad life is very good, expect a minimum of five track days. While the initial cost is high for the pads, the fact that they last numerous track days makes them more cost effective than DS2500 or EBC yellow, which tend to last no more than two track days from previous experience.
08 Carbon Black M Coupe

User avatar
RedUn
Senior Member
Senior Member
Posts: 1102
Joined: Sat Jun 16, 2012 7:33 pm
Location: Hertfordshire

CSL disc disintegrating??

Post by RedUn » Wed Nov 03, 2021 1:34 am

z4mcc wrote: Mon Nov 01, 2021 11:14 pm Update: exactly the same has happened on oem discs. Front and rear running rc5+ after 3 or so track days.

Braking performance was excellent except towards the end of the stint on only very deep into the pedal.

Running cup2’s

Not tried the skim yet but will get all 8 done most likely as the price of new is madness for 3 track days.

The pads are barely worn which is incredible as I was getting through yellow stuffs in a single day and these must be on 8.

After a skim I’ll go with a much softer pad and possible some direct to disc cooling ducts or at least remove the heat shields.

Such a strange problem. I personally feel it is the pads but a swap will see. I might try the ebc race pad or blue stuff. Or maybe ds2500
How long are you out for each time?

Cup2s will be putting a lot more heat into the brakes

Ditch the dust shields, get some carbotechs xp10 or xp8s and some rbf fluid.

If you still cook them after that then bbk time :thumbsup:
IMOLA Z4///MR

User avatar
BMWZ4MC
Lifer
Lifer
Posts: 6337
Joined: Sun Sep 13, 2009 4:24 pm
Location: Back in the sunshine

CSL disc disintegrating??

Post by BMWZ4MC » Wed Nov 03, 2021 10:01 am

Do you switch of the DSC? If not, the car will be cooking the brakes with every corner on a track day.
Image
Z4MC - heavily fettled for track use
Lotus Exige - sensible daily driver on the mods slippery slope
Westfield SEiW - in hibernation
Modified RS4 Avant - back in Blighty
S2000 GT - gone

Post Reply