Symptoms:

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

Cause:

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

Correction:

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

6T70 (Gen. 1), 6T75 (Gen. 1)

4-5-6 Accumulator Piston Kit
Part No. 124740-04K

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 first generation GM 6T70 and 6T75 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 124740-04K 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
  • No machining or special tools required
  • Piston
  • O-Rings (2) 1 Extra
  • Spring Small
  • Spring Large

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.

GM Gen. 1 6T70, 6T75 Valve Body Layout

GM Gen. 1 6T70, 6T75 Valve Body Layout
  • 6T70 (Gen. 1), 6T75 (Gen. 1) 4-5-6 Accumulator Piston Kit 124740-04K
  • 6T70 (Gen. 1), 6T75 (Gen. 1) 4-5-6 Accumulator Piston Kit 124740-04K

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.

6T70 (Gen. 1), 6T75 (Gen. 1) 4-5-6 Accumulator Piston Kit Vacuum Test Locations