The OE relief valve design and inconsistent casting pocket depth prevent proper cracking pressure at both the EPC and TCC relief valve locations. The OE relief pressures have been tested at between 40-180 psi, while the optimal range should be around 115-120 psi. This inconsistent pressure range can result in high/low EPC and line pressure, shift complaints and various converter complaints. Sonnax has developed a replacement relief valve kit that can be used in either the EPC or TCC relief pocket locations. The kit contains a .250" diameter steel checkball, which provides more consistent sealing against the separator plate. A replacement relief spring is also included for accurate pressure control. A guide spring is also included to fit securely into the machined casting pocket, which ensures the relief spring stays properly centered, and that pressure exhausts sufficiently. Machining of the casting pocket is required (using a drill press or hand-held drill) to establish an accurate depth for pressure control.
Sonnax valve body layouts provide a detailed overview of individual units making it quick and easy to determine what’s available for the specific valve body you’re working on. See all Sonnax valve body layouts.
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