Automatic transmission friction elements have 3 phases of engagement. The first, the pre-charge phase, is where the back of the empty clutch piston is filled by the hydraulics, pushing against the piston return spring until the plate clearances are taken up. The clutch isn’t capable of transmitting torque during this phase, it’s just primed and ready. This ‘rapid fill’ or ‘quick charge’ phase can be seen in the measured trace below, where the current for the oncoming solenoid spikes to achieve the rapid fill and then drops back again.
The duration of the spike is the rapid fill time, in this case for a 5-6 upshift with the C-brake engaging, and the clutch fill pressure can also be seen.



Over a period of time (i.e. years) the clutch friction plates will naturally wear slightly and the clutch piston movement required to take up the clutch pack clearance will therefore increase. Hence the need for the adaptions/adaptations to make the necessary minor adjustments to cater for this wear.

The controller also adapts the clutch pressure during the second phase of the shift, where the clutch is transmitting torque to engage the next gear by bringing the slip speed to zero. It does this by measuring the rate of change of the turbine speed during the shift, and if the gradient is too steep it backs off the pressure slightly, or increases it if the rate of speed change is too slow.

A single high adaption value often indicates a fault with a particular solenoid or a leak in a particular clutch’s hydraulic circuit (a worn rear stator bush for the E-clutch, being an obvious example) but, in your case, the fact that the adaption/adaptation values are high for all the clutches may just be an indication that the transmission has done a high mileage and is generally just ‘worn’.

One thing you could try is to remove the Mechatronic unit and carry out an air pressure test on each clutch feed port to check that there’s no excessive leakage in any of the clutches.

Phil