M3 CS Brake Question

[QED87]

I recently had the front disc's and pads changed on my 45k mile CS. They were changed because the old ones were warped and replaced by BMW main service centre.

Whilst the wheel wobble has gone I can't help but feel the brakes really aren't that strong and don't know if this is normal! To explain, if I'm pushing on and brake reasonably hard more than twice I get a groaning noise under braking and the brake pedal starts to get soft.

I'm starting to wonder whether the standard BMW brake pads are just too hard and I should go for something softer or the BMW agent fitted them incorrectly!

Does anyone have any experience of CS brakes and what I've described!

[MOTK]

Sadly the groaning noise and fade are standard equipment with E46 m3 brakes when pushing on. There is very little difference between regular M3 and the CS/CSL versions (slightly larger front disks and slightly larger pistons for the rears for CS/CSL).
You could try uprated pads and braided hoses, personally I found so little confidence in the brakes I (like many many others) went for a BBK upgrade. In my case I chose a Brembo 6 pot front and 4 pot rear setup which use the OE BMW discs. Brackets are required.

[QED87]

Thanks, I think I'll go for a set of uprated (read softer) pads and braided hoses... after spending the thick end of £600 on new discs and pads I want to get my monies worth!!!!

[MOTK]

The Brembo set up I have uses the standard CS discs front and rear so no need to change them.
If you are just going to change the pads then Pagid RS29s will be a good shout.

[161BMW]

MOTK said:

The Brembo set up I have uses the standard CS discs front and rear so no need to change them.
If you are just going to change the pads then Pagid RS29s will be a good shout.

What is the groaning sound caused by ?
Am I right in thinking u have BMW Performance front caliper ? Do Brembo make them ?
The rear caliper is that BMW Performance ?
Just saw snaps of your CS. Wow has all the comforts of the CS but all the trimming of the CSL airbox, roof, seats. So should be pretty close to CSL performance :-)

[MattOz]

The groaning noise is hot air expanding in the holes on the disk and then being released as they move past the caliper. It's standard with drilled disks. My old CS benefitted from braided lines, uprated fluid and initial some Pagid RS29's. Made a huge improvement whilst retaining standard disks and calipers. I went back to OE pads following an alloy refurb as the Pagid deposit does eat into the finish on the alloy.

[MOTK]

161BMW said:

What is the groaning sound caused by ?

As I understood it, the reason was as Matt below gives. Having changed the calipers and brand new OE disks I no longer get that noise, so not totally sure what the reason is. In itself the noise though is nothing to worry about, it's the fade that's the problem.

161BMW said:

Am I right in thinking u have BMW Performance front caliper ?

Yes

161BMW said:

Do Brembo make them ?

Yes

161BMW said:

The rear caliper is that BMW Performance ?

No (no one makes a bracket for those and they are twin pot). These are Porsche 987 boxster 4 pot brembo.

161BMW said:

Just saw snaps of your CS. Wow has all the comforts of the CS but all the trimming of the CSL airbox, roof, seats. So should be pretty close to CSL performance :-)

+ a stick
Cheers