• Erratic line pressure
  • Low line rise
  • Clutch slippage
  • Excess pump noise
  • 3-4 Clutch failure


Pressure regulator valve bore wear allows leakage and contributes to erratic pump slide movement.


Repair the valve bore and restore pressure control to the system with this oversized pressure regulator valve and reamer kit.


Casting hardness often causes adverse issues with reamer performance in the 4L60/E pump. For consistent bore finish quality and extended reamer life, recommend using Sonnax carbide tool kit 77917-TLC. This tool kit can also be used with Sonnax oversized pressure regulator valve 77917-07.

200-4R, 4L60

Oversized Pressure Regulator Valve
Part No. 77917-06

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

A worn OE pressure regulator valve can be detected in two ways. The first is a dynamometer test that reveals low line pressure during boost conditions (look for 50-100 psi less than specified in Reverse). The second is vehicle symptoms such as clutch slippage, reverse chatter and 3-4 clutch failure. Any of the above problems indicate bore wear that should be addressed.

To address pressure regulator leakage in GM 4L60, 200-4R pump covers, Sonnax offers oversized pressure regulator valve 77917-06. The Sonnax valve permits pump covers to be restored to OE specifications by correcting for wear and leakage at the pressure regulator valve.

  • Refurbish the pump cover by reaming the bore and installing an oversized pressure regulator valve
  • The pressure regulator valve helps restore control over the pressure regulating circuit by eliminating leakage

Boost valves should be checked for leakage at the same time the pressure regulator valve is being replaced. When oversizing the pressure regulator valve, it is recommended to move up one boost ratio.

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 200-4R Valve Body Layout

GM 200-4R Valve Body Layout
  • 200-4R, 4L60 Oversized Pressure Regulator Valve 77917-06
  • 200-4R, 4L60 Oversized Pressure Regulator Valve 77917-06

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.

200-4R, 4L60 Oversized Pressure Regulator Valve Vacuum Test Locations