Excess wear at the accumulator bore or on the critical diameter of the accumulator piston is common in GM Gen. 2 6T70, 6T75 and 6T80 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. Installing Sonnax 4-5-6 accumulator piston kit 124740-57K eliminates leaks to restore normal shift operation and feel.
Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.