[KNOKKi]

Hi Gus, thx for your reply. At least you read what I write. At Ferrari Chat they came up with all kinds of reactions which did not address my question, like 'measure thickness', 'buy a Carboteq', etc.

I don't understand why you use the word 'worn' in 'worn the discs', but that is maybe my English. The minimum thickness of the front discs is 36,3mm (38mm when new), so they may loose 1,7mm thickness. They are 37,6mm thick now, i.e., lost 0,4mm, so they are (0.4 / 1.7 =) 24% 'worn'. Can we agree on that? .

As with the weight, the fronts may loose 300 grams. Let's take one of the fronts which has an indicated weight when new of 6774 grams and (thus) a minimum weight of 6474 grams (also indicated on the disc). It actually weighs 6777 gram, while you would expect a loss of 0,24 x 300 grams = 70 grams and thus a weight of about 6700 grams. This is measured before any cleaning or so, but even then - looking at the disc - it is hard to see where to find 7 grams of dust, let alone the needed 70 grams.

As said, I have cleaned one of the discs (a rear disc) but that did not make any change, though quite honestly the rear discs may loose only 70 grams. The rears have lost 0,2mm width of a max of 0,5mm (32mm new, 31,5mm minimum), so they are (0,2 / 0,5 =) 40% worn - judged by their thickness - and thus should have lost around 28 grams, but as said they 'gained' weight. And again, I am willing to accept a few grams of hidden residual matter, but not the 50 grams that are needed here (i.e., the 28 grams wear and about 20 grams additional mass measured compared to new). There are no errors in measurements, everything done several times with calibrated scales and 2 persons present

So, the bottom line is 1) that I have 4 CCM discs which are between 20 and 40% worn and which all weigh more than when new and 2) that I haven't been able to find anyone else on the net who has been weighing used CCM discs (as opposed to measuring the thickness of used CCM discs), so I don't know whether my measurements are extraordinary. To be continued?