August 09, 2018
Excess wear at the accumulator bore or on the critical diameter of the accumulator piston is common in GM Gen. 2 6T70/75/80 transmissions. The 4-5-6 accumulator piston is utilized during apply of the 4-5-6 clutches to smooth engagement.
Wear at this bore allows 4-5-6 clutch apply oil to exhaust, resulting in ratio codes, harsh or delayed application of the clutch pack, burnt clutches and slipping/flares. Sometimes this wear can be addressed by installing Sonnax 4-5-6 accumulator piston kit 124740-57K. However, the casting is subject to severe wear at this location which can be beyond the ability of the non-sleeved 124740-57K kit to address.
Installing Sonnax 4-5-6 sleeved accumulator piston kit 124740-68K provides a positive sealing O-ringed sleeve to eliminate oil leaks and restore normal shift operation and feel, even in the most severely worn bores.
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.
Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.