February 21, 2013
The OE manual valve in GM 4L80-E and 4L85-E transmissions is prone to bending due to its length and relatively narrow spools. Once bent, the valve causes excess bore wear, allowing critical fluid to escape the chosen circuits. This can result in delayed engagement, low line rise and loss of gear. Installing improved Sonnax manual valve 34994-16 eliminates these problems and renews manual circuit pressure control.