Symptoms:

  • Low line pressure
  • Line pressure instability
  • No line rise
  • Burnt clutches
  • Harsh shifts
  • Shift concerns

Cause:

Isolator valve bore wear and/or broken isolator spring results in poor line pressure regulation.

Correction:

Recover hydraulic control and renew line pressure performance by installing Sonnax isolator valve kit.

6F50, 6F55, 6T70 (Gen. 1), 6T70 (Gen. 2), 6T75 (Gen. 1), 6T75 (Gen. 2), 6T80 (Gen. 2)

Isolator Valve Kit
Part No. 124740-03K

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

Vehicles with listed Ford transmissions may exhibit no line rise or low line pressure due to excess wear in the isolator valve bore. The isolator valve is in the main line pressure circuit and acts as a damper to smooth pulses from the pressure control solenoid. In addition to this wear, the OE isolator spring is under high stress and commonly breaks. Spring failure allows the end plug to shift toward the middle of valve body, allowing unrestricted exhaust for main line pressure. Spring breakage can also cause isolator valve to jam in the bore, preventing the dampening effect that protects against line pressure instability. Either of these concerns can lead to undesirable shift operation and burned clutches. Installing Sonnax isolator valve kit 124740-03K restores proper line pressure control for renewed shift feel and performance.

  • O-Rings added to valve and end plug to ensure positive seal
  • Annular grooves help center valve in bore to reduce future side-load wear
  • Spring shot-peened to reduce fatigue and eliminate premature failure
  • 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.

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

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

GM Gen. 2 6T70, 6T75, 6T80 Valve Body Layout

GM Gen. 2 6T70, 6T75, 6T80 Valve Body Layout

Ford 6F50, 6F55 Valve Body Layout

Ford 6F50, 6F55 Valve Body Layout
  • 6F50, 6F55, 6T70 (Gen. 1), 6T70 (Gen. 2), 6T75 (Gen. 1), 6T75 (Gen. 2), 6T80 (Gen. 2) Isolator Valve Kit 124740-03K
  • 6F50, 6F55, 6T70 (Gen. 1), 6T70 (Gen. 2), 6T75 (Gen. 1), 6T75 (Gen. 2), 6T80 (Gen. 2) Isolator Valve Kit 124740-03K

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.

6F50, 6F55, 6T70 (Gen. 1), 6T70 (Gen. 2), 6T75 (Gen. 1), 6T75 (Gen. 2), 6T80 (Gen. 2) Isolator Valve Kit Vacuum Test Locations