sonnax-black Facebook-color LinkedIn-color maillink printlink r_and_r_only SERVOFIX-logo-web Twitter-color VBFIX-logo-web video-logo-web warranty_only Youtube-color


  • Burnt clutches
  • Erratic line pressure
  • Low converter & lube flow
  • Overheating
  • Poor shift quality
  • TCC apply & release concerns


Continuous oscillation of pressure regulator valve results in excess bore wear, allowing line pressure to exhaust and/or blocking converter feed oil.


Restore line pressure performance and renew converter feed by reconditioning the bore and installing Sonnax oversized pressure regulator valve kit.

6T40 (Gen. 1), 6T45 (Gen.1), 6T50 (Gen. 1)

Oversized Pressure Regulator Valve Kit
Part No. 144510-01K

You need this if... View Instructions

GM 6T40, 6T45 and 6T50 first generation transmissions may exhibit multiple line pressure and converter-related problems due to high wear in the main pressure regulator bore. Wear at the balance spool end allows critical fluid loss, resulting in excess line pressure, harsh shifts, and reduced cooler/converter flow. Wear at the outboard spool robs converter feed pressure and lowers line pressure, resulting in soft shifts and burnt clutches. Reconditioning the bore and installing Sonnax oversized pressure regulator valve kit 144510-01K restores hydraulic integrity for proper line pressure control in all ranges.

  • Oversized pressure regulator valve and matched spring restore OE function
  • Hardcoat anodized aluminum valve combats premature wear
  • Annular grooves help center valve in bore to reduce future side-load wear

Must use 1/2" or thicker spacer plate between pump body and VB-FIX; see instructions for details.

  • Valve
  • Spring
  • End Plug

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 6T40 (Gen. 1), 6T45 (Gen.1), 6T50 (Gen.1) Valve Body Layout

Gm 6t40 gen1 vbl thumb

October 31, 2014

GM 1st Gen. 6T40, 6T45, 6T50 Vacuum Test Guide

Topics: Vacuum Test Guides Vacuum Testing Transmission GM 6T45 (Gen.1) Transmission 6T50 (Gen. 1) Transmission 6T40 (Gen. 1) Transmission

Read Now

September 30, 2005

Anatomy of a Transmission: Oil Flow in the Pump-PR-Converter-Cooler Lube Circuits

Gregg Nader

Topics: Diagnostics And Theory Transmission

Read Now
  • 144510 01k combo
  • 144510 01k

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.

  • 144510 01k in test