I recently had an X431, and I realize that the clutch wear calculation on my 4200 is incorrect. Have you noticed this problem on others vehicles, Maserati or Ferrari in particular ? Do you have diag reports (SDx, MVDCI, Leonardo, Texa or others) where these values appear ? 1 / How is wear calculated? It is quite simply the difference between the current wear and the theoretical maximum. For this, the system makes the difference between the position of the clutch release bearing when the assembly is new and the current position. The formula is simply (given in the Maserati training manual): Image Unavailable, Please Login The thickness of 5.6 mm represents the maximum wear, reduced to the stop. At each friction, this value is of course less important since it is necessary to take into account the presence of 2 discs and the ratio (around 4) generated by the lever arms of the diaphragm of the clutch. For information, Ferrari indicates 0.8mm of maximum wear for 1 disc for the F430. This value has no reason to be different on the other vehicles in the group. 2 / MDVCI diag report Diag made in the network with the official tool Image Unavailable, Please Login The manual calculation from the stop positions (24.60mm and 21.09mm, maximum wear 5.6mm) gives a value of 62.68%. This is consistent with the 62.76% indicated, the difference must be linked to the rounding to 2 decimal places of the displayed values. 3 / Leonardo diag report Same vehicle, shortly after: Image Unavailable, Please Login The system indicates 1 more decimal place. The calculation from these values gives 58.96%, everything is fine! 4 / Diag X431 Always the same car: Image Unavailable, Please Login Cool, the clutch has rejuvenated! So, on closer inspection: ((24,53-21,08) / 5.6) * 100 = 61.61% We then find a coherent value. 5 / Conclusion: The measurements made with the X431 are good but the constant used for the % wear is incorrect (7mm ALD 5.6mm).