Symptoms:

  • 2-3 Flare
  • 2-3 Harsh
  • 5-6 Flare
  • 5-6 Harsh
  • Bump shifts

Cause:

Relentless K1 valve oscillation scrubs the bore, causing wear that allows critical control pressure to exhaust.

Correction:

Recover hydraulic control and renew K1 operation by reconditioning the bore and installing Sonnax oversized K1 regulator valve.

722.9

Oversized K1 Regulator Valve
Part No. 88740-08


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

The K1 clutch in Mercedes 722.9 transmissions is applied in third, fourth and fifth gears. The K1 regulator valve controls the apply rate of this clutch. Excess bore wear here permits pressure escape from the circuit, resulting in clutch apply timing problems such as flares and harsh or bump shifts. Reconditioning the bore and installing Sonnax oversized K1 regulator valve 88740-08 returns precise shift control by re-establishing hydraulic integrity in the K1 circuit.

  • Hardcoat anodized aluminum valve combats premature wear
  • Annular groove helps center valve in bore to reduce future side-load wear

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.

Mercedes 722.9 Valve Body Layout

Mercedes 722.9 Valve Body Layout
  • 722.9 Oversized K1 Regulator Valve 88740-08
  • 722.9 Oversized K1 Regulator Valve 88740-08

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.

722.9 Oversized K1 Regulator Valve Vacuum Test Locations