Z4MC brake corrosion

[tt205]

Hi,

I'd appreciate some expert advice before replacing all discs and pads on my car...
Car is a Dec06 Z4MC with 29k on the clock, used daily on a mix of motorways and A/B roads (where the brakes get harder use).

I've asked BMW to explain why brakes are very noisy and vibrate the car a little.
Their answer is that the discs are corroded, most likely due to occasional use of car and/or not hard use of brakes, resulting in the discs not being scrubbed properly and corrosion building up. Rear discs are worst and quite dull across a lot of the face. Fronts are better, but have blue/grey colouration around the drilled areas.

Lack of use seems unlikely cause of corrosion in my case but perhaps i don't use the brakes hard enough as pads are only 2/3rds worn after 29k...? They are applied reasonably hard from high speeds most days though, but no track use.

I'd appreciate advice or maybe confirmation of what i've been told before spending approx 1k getting everything replaced. Happy to spend the money if it's fair, but does surprise me that they have corroded as i've never had that with any car before. I'm no expert though!

Cheers!

[TheEnd]

The slight discolouration suggest they are getting hot enough, but it might be down to bedding.

Pad material is supposed to be deposited in small amounts on the disc, in an otherwise invisible layer, and the majority of vibrations is from unequal deposits.
I know it sounds like snake oil, with a mysterious invisible coating that is causing the problem, but it's a possibility that the occasional heavy use mixed in with light use can upset the balance.
I doubt you'd get much further with BMW though, unless under warranty, but they could still explain it away as a feature from your driving style, and you'll have nothing to argue against.
Some people have found harsher sportier pads will solve the problem as they will turn over the deposits quicker, although they'll also wear the discs more.

[mmm-five]

You could always give the discs a scrub with some sandpaper/emery cloth. Or you could pay to have them skimmed at an engineering company - assuming there's enough meat on them to do that.

The last option is to replace them completely - which should cost around £650 plus whichever pads you chose (I've just had mine done at Darjac Racing near Colchester).
You can stick to BMW pads or change them for EBC red/yellowstuff, Pagid Blue, Ferodo DS2500.

[derin100]

mmm-five said:

You could always give the discs a scrub with some sandpaper/emery cloth. Or you could pay to have them skimmed at an engineering company - assuming there's enough meat on them to do that.

The last option is to replace them completely - which should cost around £650 plus whichever pads you chose (I've just had mine done at Darjac Racing near Colchester).
You can stick to BMW pads or change them for EBC red/yellowstuff, Pagid Blue, Ferodo DS2500.

I was thinking about the scrubbing/sanding thing myself (on different cars). Any particular technique, grade of paper recommendations as I have never done this myself before?

Many thanks in advance.

[andye30m3]

I thought the vibration cause when braking is normally due to warped discs which comes down to them having over heated.

Are z4MC brakes the same as E46 M3 brakes?

I've not heard great reports about BMW M-brakes over the years it does seam to be an element which lets the cars down, and I expect saves BMW cash.

If you've warped a set of standard discs is it worth looking at upgrading either using better quality disc (I was recommended Stoptech when looking to use E46 M3 discs with 840 brembo calipers on my E36)

or upgrading to and AP or similar set up as I believe a number of M3 CSL owners have.

[derin100]

Andy,

I believe actual 'warping' of the discs is a bit of a myth.
I found this to be a good, clear explanation:

http://www.stoptech.com/tech_info/wp_warped_braked...

[Frik]

derin100 said:

Andy,

I believe actual 'warping' of the discs is a bit of a myth.
I found this to be a good, clear explanation:

http://www.stoptech.com/tech_info/wp_warped_braked...

Good old Carroll Smith, god rest his soul. Always straight talking

Motorway driving is the worst thing for affecting DTV because you only graze the surface, exacerbating any variation that is already there.

[The Milfman]

derin100 said:

Andy,

I believe actual 'warping' of the discs is a bit of a myth.
I found this to be a good, clear explanation:

http://www.stoptech.com/tech_info/wp_warped_braked...

Interesting read, thanks.

[Slurms]

andye30m3 said:

Are z4MC brakes the same as E46 M3 brakes?

Not exactly, they are the same as fitted to the M3 CSL, M3 CS but are larger than the ones fitted to the stock E46 M3

[andye30m3]

derin100 said:

Andy,

I believe actual 'warping' of the discs is a bit of a myth.
I found this to be a good, clear explanation:

http://www.stoptech.com/tech_info/wp_warped_braked...

Thanks for the link, It makes for an interesting read.

[tt205]

Thanks all for advice. And the stoptech article was really interesting and educational :-) so thanks for that too.
BMW kindly cleaned my discs up and bed the pads back in (for free!) which has improved things quite a bit, but still nowhere near perfect. I decided to consider my options before shelling out on new BMW brakes...
Has anyone had alternative discs/pads fitted on their Z4M? and what's the verdict?

Cheers!

[ben]

tt205 said:

Thanks all for advice. And the stoptech article was really interesting and educational :-) so thanks for that too.
BMW kindly cleaned my discs up and bed the pads back in (for free!) which has improved things quite a bit, but still nowhere near perfect. I decided to consider my options before shelling out on new BMW brakes...
Has anyone had alternative discs/pads fitted on their Z4M? and what's the verdict?

Cheers!

Why not come over here ( http://www.z4-forum.com/) for a look

[mmm-five]

We heard you the first time

[tt205]

Cheers Ben - am on there, same username :-)
5minutes of looking around and already decided i need GruppeM induction and H&S exhaust - could get expensive!!

[mmm-five]

Not forgetting the carbon roof, proper bucket seats and possibly an ESS supercharger ;-)