CSL disc disintegrating??

z4mcc · Post by **z4mcc** » Sat Sep 12, 2020 4:34 pm

Hi All,

has anyone seen an issue like this on their e46 m3 csl / z4m discs?

it looks like the face is disintegrating. I thought the dull spots we’re pad build up but it’s actually indentation.

I can’t see any min thickness stamped into the discs so I wonder if this are non bmw part discs.

mmm-five · Post by **mmm-five** » Sat Sep 12, 2020 4:58 pm

Not seen that sort of wear on any my discs. Surface corrosion, pitting, micro-cracks, pad transfer, yes, but nothing like that.

The closest I've ever see to that was when an acquaintance decided to spruce up his e34 M5's discs by getting them chrome-plated - and wondered why braking performance had gone off a cliff

Part number & min thickness should be on the shoulder of the bell/hat.

: 320050_x800.jpg (56.89 KiB) Viewed 1433 times

Part numbers should be 2282446 for RHS and 2282445 for LHS.

RedUn · Post by **RedUn** » Sat Sep 12, 2020 6:36 pm

That's not the discs, it looks like pad backing to me. You got any pads left?

z4mcc · Post by **z4mcc** » Sat Sep 12, 2020 7:59 pm

Loads of pad left yes. The lack of part numbers and stamping is very suspicious.

Is it still cotswolds for best price on new discs. Thruxton is next and it would be nice to have brakes

R60BBA · Post by **R60BBA** » Sat Sep 12, 2020 10:08 pm

z4mcc wrote: ↑Sat Sep 12, 2020 7:59 pm Loads of pad left yes. The lack of part numbers and stamping is very suspicious.

Is it still cotswolds for best price on new discs. Thruxton is next and it would be nice to have brakes

Cotswolds stopped being the cheapest a while ago.

I find Rybrook Warwick, Harry Fairbairn and Douglas Park Hamilton to be cheaper.

Having said that, I got a quote for new discs and pads for circa £512 from main dealer. Yet fitted at main dealer was £520...so in the end I ended up paying the extra £8 for them to be fitted...

mr wilks · Post by **mr wilks** » Sun Sep 13, 2020 10:24 am

z4mcc wrote: ↑Sat Sep 12, 2020 7:59 pm Loads of pad left yes. The lack of part numbers and stamping is very suspicious.

Is it still cotswolds for best price on new discs. Thruxton is next and it would be nice to have brakes

Those discs have barely covered a couple of thousand miles , why would you replace them if they still function

RedUn · Post by **RedUn** » Sun Sep 13, 2020 10:29 am

z4mcc wrote: ↑Sat Sep 12, 2020 7:59 pm Loads of pad left yes. The lack of part numbers and stamping is very suspicious.

Is it still cotswolds for best price on new discs. Thruxton is next and it would be nice to have brakes

Part numbers on the discs or pads?

They've got too hot either way, what pads are you using?

Discs should clean up as mr wilks says

z4mcc · Post by **z4mcc** » Sun Sep 13, 2020 2:58 pm

Huge brake judder when hot. Rc6 pads.

Might be worth giving them a skim.

They are 27.8mm so plenty of thickness left.

It won’t clean up as it’s not deposits. It’ll need to ware down.

colb · Post by **colb** » Sun Sep 13, 2020 3:38 pm

Something wrong with the metal those have been made from, pads should have produced a smooth surface over the face of the disc, are both sides showing up the same condition? You could try having them skimmed and see if it returns, if it comes back then I would change them for a reputable brand with new pads.

Muckinonthesofa · Post by **Muckinonthesofa** » Mon Sep 14, 2020 4:09 am

I'm always on the look out for consumables and I've noticed that disc prices have gone up a lot lately, I'm sure c£250 would get you a pair of fronts not too long ago!

MrPT · Post by **MrPT** » Mon Sep 14, 2020 8:59 am

Very odd. I wonder if they built up an uneven layer of rust at some point and were then “etched” by subsequent usage?

Skimming would get my vote.

RedUn · Post by **RedUn** » Mon Sep 14, 2020 2:24 pm

z4mcc wrote: ↑Sun Sep 13, 2020 2:58 pm Huge brake judder when hot. Rc6 pads.

Might be worth giving them a skim.

They are 27.8mm so plenty of thickness left.

It won’t clean up as it’s not deposits. It’ll need to ware down.

Just had a quick Google, not fully upto speed on CL pads, from the specs they sound very harsh, oem discs have never been designed to run at them sort of temperatures.

I think a skim is the way forward, it'll just happen again with them pads though unless you manage to improve the cooling?

Pbondar · Post by **Pbondar** » 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

z4mcc · Post by **z4mcc** » 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.

Pbondar · Post by **Pbondar** » Mon Sep 14, 2020 9:35 pm

Stainless steel materials gall very easily....common problem with stainless steel nuts n bolts with threads damaging..

One of the main reasons most discs are made of high grade cast iron..

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