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  • 4-5 Flare
  • 4-5 Harsh
  • Delayed engagement
  • Harsh engagement


B2/BR bore wear allows critical pressure breach that prevents normal clutch control.


Recover hydraulic control and renew Forward and Reverse operation by reconditioning the bore and installing Sonnax oversized B2/BR regulator valve kit.


Oversized B2/BR Regulator Valve Kit
Part No. 88740-04K

You need this if... View Instructions

The B2 clutch in Mercedes 722.9 transmissions is applied in first through fourth gears, and the BR clutch is used during Reverse operation. The B2/BR regulator valve controls the apply rate for these clutches. Bore wear at the B2/BR regulator valve allows pressure loss that affects clutch apply timing, resulting in harsh engagement, delayed Forward and Reverse, flares, and harsh 4-5 shifts. Reconditioning the bore and installing Sonnax oversized B2/BR regulator valve kit 88740-04K renews critical clearances to restore normal Forward and Reverse operation.

  • Hardcoat anodized aluminum valve combats premature wear
  • Annular grooves help center valve in bore to reduce future side-load wear
  • Lengthened critical spool provides added stability and wear prevention
  • Valve
  • Spring

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

Merc7229 vbl
  • 88740 04k combo
  • 88740 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.

  • 88740 04k in test