Grumbling brakes after airfield day, BMW M Coupe (s50)
Discussion
Oh dear, seem to have some unhappy front brakes. Went to Woodbridge Airfield yesterday ( organised by Javelin - was very well run BTW...).
I did the following
-3 sighting laps
-4 hot laps, 1 cool down
-4 hot laps, 1 cool down ( brakes started to grumble after lap two)
-4 not so hot laps (maybe a spot of drifting where possible / safe) and 1 cool down lap
I then drove 100 miles home, the brakes dont judder like a warped disk ( cant feel it through the steering wheel) but they do grumble when applied. The Disks also look a bit patchy - not a unfifrom sliver, some bits look 'milky'???
What have I done, do the disks need a skim, or is it the pads?
I did the following
-3 sighting laps
-4 hot laps, 1 cool down
-4 hot laps, 1 cool down ( brakes started to grumble after lap two)
-4 not so hot laps (maybe a spot of drifting where possible / safe) and 1 cool down lap
I then drove 100 miles home, the brakes dont judder like a warped disk ( cant feel it through the steering wheel) but they do grumble when applied. The Disks also look a bit patchy - not a unfifrom sliver, some bits look 'milky'???
What have I done, do the disks need a skim, or is it the pads?
Not sure what the problem is.
What pads are you using?
I would check them. Seems like you may have cooked the pad and / or glazed them up. So you can either remove the glaze on a flat surface, gently rubbing the face of the pad in a circular motion or buy new ones. They may well fall apart when you take them out.
If the pads look ok then clean the discs down with brake cleaner and see how that goes.
Alternatively, go to Frost Motorsport in Ipswich who can have a look and sort out for you.
What pads are you using?
I would check them. Seems like you may have cooked the pad and / or glazed them up. So you can either remove the glaze on a flat surface, gently rubbing the face of the pad in a circular motion or buy new ones. They may well fall apart when you take them out.
If the pads look ok then clean the discs down with brake cleaner and see how that goes.
Alternatively, go to Frost Motorsport in Ipswich who can have a look and sort out for you.
The fact that they are OEM is probably part of the answer or question. 15 laps is all you did and it killed the brakes
I would suggest getting a set of more track / race orientated pads in it for trackdays, plus making sure that the brake fluid is up to scratch. I would imagine OEM brake fluid would cook quite quickly especially if its been in the car for a couple of years.
Im only talking from a general track / race perspective. I have no knowledge of how good OE brakes are on a beemer.
I would suggest getting a set of more track / race orientated pads in it for trackdays, plus making sure that the brake fluid is up to scratch. I would imagine OEM brake fluid would cook quite quickly especially if its been in the car for a couple of years.
Im only talking from a general track / race perspective. I have no knowledge of how good OE brakes are on a beemer.
My e34 M5 used to have the same problems, but only after about 10 hard laps of Elvington.
I never did anything other than drive normally for the next 4 weeks (over 1,000 miles usually) and they'd have settled down before my next track day. That was with standard 343mm discs and Ferodo DS2500 pads.
I never did anything other than drive normally for the next 4 weeks (over 1,000 miles usually) and they'd have settled down before my next track day. That was with standard 343mm discs and Ferodo DS2500 pads.
Does the Z3M use the sanme pads as the e36/e46 M3's?
If so, I have a virtually brand new set of EBC Yellowstuff pads you can have cheap.
My advice however would be to get something better. Why do you think I have a virtually brand new set to sell, even though they fit my current car.
If so, I have a virtually brand new set of EBC Yellowstuff pads you can have cheap.
My advice however would be to get something better. Why do you think I have a virtually brand new set to sell, even though they fit my current car.
Edited by Paul_M3 on Tuesday 11th August 17:04
RatBoy M3CS said:
In my exp of track day brakes... save yourself the learning curve and go straight for the Pagid RS 19/29's.. they work..!.. 
100% correct. I owned my e36 M3 for 2.5 years, and never changed pads because they were worn out.It was always because they were useless.
I was only happy when I finally got the Pagids. May have been bloody expensive, but would have saved me money in the long run.
I had an identical problem with my E36 328 track hack. A groaning sound, but no vibration when hard on the brakes.
It never seemed to affect the performance, but was a little disconcerting.
After investigation, mine was due to micro cracks on the surface of the swept area of the disc. My best gues is that the temperature difference between swept and unswept areas was too high and caused the disc to yield while hot. When it cooled, this puts stress into the disc which responds by cracking.
The cracks were only around 1-2mm long, always radial to the disc centre and around 2-3 mm apart. tough to see without the removal of the wheel and getting up close with a torch. I used a dye pen on the discs to confirm it.
Worth a look on a weekend, just in case.
It never seemed to affect the performance, but was a little disconcerting.
After investigation, mine was due to micro cracks on the surface of the swept area of the disc. My best gues is that the temperature difference between swept and unswept areas was too high and caused the disc to yield while hot. When it cooled, this puts stress into the disc which responds by cracking.
The cracks were only around 1-2mm long, always radial to the disc centre and around 2-3 mm apart. tough to see without the removal of the wheel and getting up close with a torch. I used a dye pen on the discs to confirm it.
Worth a look on a weekend, just in case.
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