Common complaints in vehicles with AODE and 4R70W transmissions is low line pressure resulting or band and/or clutch failure, or throttle-sensitive buzz, especially when hot. These issues can be caused by severe wear at the outboard pressure regulator valve spool or bore area. Wear at this location allows EPC oil to leak to exhaust, resulting in poor line rise. As oil temperature increases it becomes less viscous, an more leakage occurs. Wear at the inboard balance spool bore is also very common, which can result in excessively high lie pressure that can damage the case. The Sonnax oversized pressure regulator valve and matching boost valve kit 76948-16K restores valve-to-bore clearances so the pressure regulator valve can maintain correct pressures.

• Improved PR/EPC reaction area ratio provides higher line rise response to EPC pressure, which results in noticeably firmer shifts.
• Hard-coat anodized aluminum oversized pressure regulator valve resists wear.
• Annular grooves added to oversized pressure regulator valve prevent side loading wear.