Symptoms:

  • 5-4 Flare
  • 5-4 Neutral
  • No 4-5
  • VFS 1/A solenoid control code
  • Delayed Forward
  • Harsh Forward

Cause:

OE boost sleeve wears prematurely, allowing critical pressure loss and/or seizure of valve within sleeve.

Correction:

Recover hydraulic control and renew shift performance by installing Sonnax clutch A & E control boost valve kit.

ZF6HP21, ZF6HP28, ZF6HP34

Clutch A & E Control Boost Valve Kit
Part No. 95740-28K

Sevices 2 bores

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

ZF6HP21/28/34 (Generation 2) transmissions are equipped with an aluminum sleeve for the clutch A and E control boost valve. This material is prone to wear from valve plunger reciprocation. Failure of this sleeve results in a variety of shift problems and solenoid codes. The Sonnax clutch A and E control boost valve kit 95740-28K will restore the correct hydraulic clearance and proper function of the assembly.

  • Hardcoat anodized aluminum valve combats premature wear
  • Sleeve is highly wear-resistant to increase service life

Kit is NOT compatible with ZF6HP19/26/32 (Gen.1) units. To differentiate between Gen. 1 and Gen. 2 valve bodies, see ZF Identification Guide.

  • Valves (2)
  • Sleeves (2)

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.

ZF6HP21/28/34 (Gen. 2) Valve Body Layout

ZF6HP21/28/34 (Gen. 2) Valve Body Layout
  • ZF6HP21, ZF6HP28, ZF6HP34 Clutch A & E Control Boost Valve Kit 95740-28K
  • ZF6HP21, ZF6HP28, ZF6HP34 Clutch A & E Control Boost Valve Kit 95740-28K
  • ZF6HP21, ZF6HP28, ZF6HP34 Clutch A & E Control Boost Valve Kit 95740-28K details

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.

ZF6HP21, ZF6HP28, ZF6HP34 Clutch A & E Control Boost Valve Kit Vacuum Test Locations