November 14, 2016
Common problems in Ford 4R70E, 4R70W, 4R75E and 4R75W transmissions include a burned overdrive band, loss of 4th Gear, and/or a 4-3-Neutral shift pattern. These problems can be caused by wear at the inside diameter of the overdrive servo regulator boost valve sleeve due to constant oscillation. Excess wear allows valuable overdrive oil to leak, preventing the proper regulation of the overdrive servo. Sonnax overdrive servo regulator kit 76948-29K maintains critical tolerances that re-establish the hydraulic integrity of the circuit.
Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.