September 21, 2005
The coast clutch valve functions differently in 4R44E/55E units and 5R44E/55 units. The valve is the same but the porting used in their different separator plates makes the difference and will create different complaints as a result of valve or bore wear. In the 4R units, this valve is needed to get proper overdrive servo apply and bring on coast clutch. In the 5R units, the valve is needed to vent overdrive servo release oil and to bring on the coast clutch. Engine braking or loss of coast clutch are common complaints in either unit. Complaints of loss of 4th gear in a 4R or loss of 2nd or 5th gear in a 5R are associated with this valve. The Sonnax oversized coast clutch valve kit 37947-33K and tooling salvages the valve body and restores proper coast clutch function in either style unit.
Although this valve can be used on any valve body independent of other repairs, we strongly suggest this kit be used with Sonnax Converter Regulator Sleeve Kit 37947-09K. These two line-ups share the same bore and are both commonly worn.