September 30, 2005
Worn bores in the Ford CD4E and Mazda LA4A-EL converter bypass line-up reduce TCC control and cooler flow. This results in bushing or planet failure, reduced converter clutch life from overheating and often results in codes 628/1744/1740. Slippage codes are often generated as the unit comes up to operating temperature. As the temperature rises, valve control becomes poor and excessive clearance creates excessive leakage of converter pressure.
Sonnax oversized bypass clutch control valve kit 73840-BK features a tightly toleranced sleeve and plunger valve to prevent leakage, and an oversized and improved design bypass clutch valve.
This kit cannot address high line pressure in the PR balance circuit, which can break up parts and reduce flow into the converter/cooler circuits. For information on that repair, see part number 73840-RK.