September 24, 2010
Line rise control in the AODE/4R70W is different than in most units. Forward pressure is controlled by EPC oil reacting directly on the spring end of the PR valve. The OE boost assembly only increases pressure in reverse. Traditional use of a larger ratio boost valve to increase line pressure has not been an option for this unit.
Sonnax has created a specially designed boost assembly that introduces a supplemental boost valve to augment line rise in forward ranges. Like other Sonnax line pressure booster kits, this special boost valve adds EPC reaction area, providing higher pressure incrementally and when it is needed the most. Combined with a spring that is approximately 10% stronger than OE and more conservative in impact than other aftermarket kit springs, this unique Sonnax booster kit gives you the best of both worlds: a modest pressure increase at the low end, with a high-end pressure that is equal to or greater than that of other aftermarket kit springs.
Sonnax booster kit components are uniquely designed for precision pressure control. At low-end pressures, they deliver normal engagements, normal light throttle shifts and smooth coastdown shifts. When vehicles are pushed harder, components progressively increase pressure for improved clutch holding capacity and increased durability.