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Interpreting Transmission Adaptation Values
Transmission adaptation, usually in terms of fill time and pressure, can let us know the condition of an automatic transmission. This article discusses how to interpret the values.
Published by Dr Jiulin Teng on 18 Aug 2026
Keywords: transmission
Modern, electronically-controlled automatic transmissions are designed to adjust how clutch packs are applied for shift quality over much of its service life. In the control module, this is reflected as Adaptation values, usually in terms of fill time and pressure for the pistons. These data points provide direct evidence to transmission wear, even when there is no perceivable degradation in shift quality.
- A positive adaptation value for fill time indicates internal hydraulic leak. This is usually from either the seal between the mechatronics and the transmission housing, the piston, or the various bushings. As pressure is released elsewhere, more time is needed for the friction discs to bite.
- A positive adaptation value for fill pressure indicates wear on the friction discs. As they become less effective, higher pressure is needed to hold the engagement. Obviously, it could also confound with hydraulic leak.
- A badly-worn clutch pack that has deformed may start biting earlier, causing large negative adaptation values for fill time. However, at this point there should be considerable shift quality issues. Otherwise, negative adaptation value within the acceptable range is a good thing.
Below, I show the adaptation values for my old 722.9 transmission. They show that the internal wear is minimal; however, it also shows that there are hydraulic leaks for brake B2 and clutch K3. This is understandable, because they are both fed by the output shaft and passes through the B2 housing. I guess a bushing is worn. Unlike some other common designs, there is no seal between the valve body and the transmission housing.
Gallery: Transmission Adaptation 722.9
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