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Technical

TF80SC Gen 1 2-3 flared shift

Tech-Talk-April-Figure-4

The complaint

A 2005 Volvo XC90 equipped with the TF80SC Gen 1 transmission has a complaint of a 2-3 flared shift. During the overhaul process a brand-new valve body from the dealer was installed, only to find on the initial road test that a 2-3 flared shift still existed. The adaption procedures were performed but the complaint persisted.

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The technician thought that there may be a friction plate incompatibility issue, but that idea was dismissed due to the fact that original equipment friction plates were installed yet the 2-3 flared shift remained.

The cause

The factory calibration setting for the C3 Clutch Control Valve was not correct for this vehicle application.

The correction

Since turning the C3 Clutch Control Valve adjusting screw out increases pressure, the screw was turned out one and a half turns, as seen in figure 1 (above). This eliminated the 2-3 flared shift complaint.

Summary

The technician said that this 2-3 flared shift complaint has since been corrected three more times by using the same procedure all with brand new OEM valve bodies.

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There are clutch control valve adjusters for the B1, C1 and C2 clutch control valves in addition to the C3. Turning these screws out one quarter of a turn will increase clutch pressure by approximately 4 PSI. It is suggested that turning the screw out one half turn to begin with and then see what the result of that adjustment produces. The chart in figure 2 (below) indicates which solenoid controls which clutch.

Tech-Talk-April-Figure-5

Builder’s Note: Always mark the original clutch control valve adjustment screw position in the event that it must be returned to the original setting.

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