• 3-4 Flare
  • Ratio codes
  • 4-5-6 Clutch burned
  • Slipping gears
  • 3-4 Harsh


Wear at the accumulator piston bore or on the critical diameter of the accumulator piston allows clutch apply oil to exhaust.


Recover hydraulic control and renew shift feel and performance by installing Sonnax 4-5-6 accumulator piston kit.

6T70 (Gen. 2), 6T75 (Gen. 2), 6T80 (Gen. 2)

4-5-6 Accumulator Piston Kit
Part No. 124740-57K

You need this if... View Instructions Find a Distributor

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.

  • O-Ring incorporated for positive sealing, even in worn bores
  • Annular grooves help center piston in bore to reduce future side-load wear
  • Hardcoat anodized aluminum piston combats premature wear

  • Piston
  • O-Rings (2) 1 Extra
  • Spring Small
  • Spring Large
  • 124740 57k combo
  • 124740 57k

You need this if...

Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.

  • 124740 57k test