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.

Improves OD roller clutch holding power in D4 and Reverse ranges
Extends the life of workhorse transmissions while preventing warranty claims and comebacks
Installs quickly onto the valve body — no transmission removal needed


Range
Gear
Overrun Clutch with
Sonnax 34200-40K
Clutch Valve Kit
Overrun Clutch
with OE
Clutch Valve


Park

Applied


Reverse

Applied


Neutral

Applied


Overdrive
1st
Applied


2nd
Applied


3rd
Applied


4th



Drive
1st
Applied
Applied

2nd
Applied
Applied

3rd
Applied
Applied

D2
1st
Applied
Applied

2nd
Applied
Applied

D1
1st
Applied
Applied

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