Various TCC concerns and failures are common problems with Ford 4R70E, 4R70W, 4R75E, 4R75W and AODE transmissions. Many of these can be traced to excess wear, and/or binding at the converter limit valve. Wear at the inboard spool can allow valuable converter pressure to exhaust. Debris related wear and bore damage at the outboard spool can create binding of the valve such that it sticks in either a high or low converter limit pressure position. When the converter limit valve is not able to supply the proper regulated line pressure to the converter circuits, converter shudder and slip can results. If the valve becomes stuck in the high pressure position, it can prevent proper limiting of pressure into the converter circuit, resulting in damaged or ballooned converters.
Reconditioning the bore and installing Sonnax oversized converter limit valve 76948-58K eliminates this wear and binding, thus better controlling the pressure into the converter circuit.
Valve is binding/stuck in the bore, or does not stroke smoothly. Or if vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.