• Delayed engagement
  • Wrong gear starts
  • Flare shifts
  • Gear ratio & solenoid codes
  • Harsh shifts
  • Neutral shifts
  • Gear loss


Bore wear at the priming valve allows pressure escape that causes drivability problems.


Stop pressure loss and restore normal solenoid feed pressures by reconditioning the bore and installing Sonnax oversized priming valve kit. 

845RE, ZF8HP45, ZF8HP55, ZF8HP70

Oversized Priming Valve Kit
Part No. 35740-21K

ZF valve name: DR-RED-V (DR-V)
Chrysler valve name: PR-V

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

In Chrysler 845RE and ZF8HP45/55/70 units, the variable force solenoids control clutch apply/release, torque converter clutch apply/release and line pressure. The priming valve insures proper flow and pressure to the solenoids, and is especially crucial during hot conditions and low pressure. Low solenoid feed pressure at idle can create delayed engagement or wrong gear starts. This priming valve also limits the maximum pressure to all the solenoids. Excessive solenoid feed pressure can flood the solenoids causing gear ratio codes, harsh up/down shifts and excessive line pressure. Reconditioning the bore and installing Sonnax oversized priming valve kit 35740-21K eliminates bore wear and stops leakage for proper solenoid pressure control.

  • Hardcoat anodized valve combats premature wear
  • Annular grooves help center the valve in the bore to resist wear
  • Valve
  • Spring
  • End plug
  • O-Rings (3) 1 Extra

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.

ZF8HP55 Valve Body Layout

Zf8hp55 vbl thumb

ZF8HP45, ZF8HP70 Valve Body Layout

Zf8hp45 70 vbl thumb
  • 35740 21k

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.

  • 35740 21k in test