Insufficient holding power in the overdrive roller clutch is the underlying cause of chronic overdrive roller clutch failure in hardworking 4L80-E and 4L85-E transmissions. When the roller clutch fails, the damage can be catastrophic and the only fix is replacing the drum, planetary assembly and mating components.
The Sonnax Smart-Tech overrun clutch valve kit 34200-40K offers a hydraulic solution to this known mechanical problem. With unique rerouting of hydraulic fluid pressure, this patented kit keeps the overrun clutch applied at all times (except OD 4th), reinforcing the roller clutch to adequately support heavy loads.
Any other modifications to the valve body should be completed prior to installing Sonnax Smart-Tech® overrun clutch valve kit. With minor lube tube modification, the Sonnax kit can be installed in ’92-’96 units.
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