When your hunt for automotive performance gains turns to upgrading your transmission and shifting performance, it’s important not to overlook the “brains of the transmission” — the valve body.

In this edition of Carl’s Tech Talk video series from Summit Racing, tech expert Carl Pritts will walk you through the process of modifying your transmission’s valve body.

Transmission performance is all about sending the right amount of hydraulic fluid pressure to the right place at the right time, which requires two key components:

  1. A pump to draw fluid from the oil pan.
  2. Something to direct flow to clutches and servos.

Enter the valve body.

If you’re considering modifying the transmission valve body, the usage, amount of power, and expected performance gains for your vehicle are what you’ll use to choose what to change. Choices include:


Shift Improver Kits

  • Cost-savings potential
  • Great for adding firmness and extra rpm between full-throttle shifts on working transmissions

What you’ll need: Patience, mechanical skills, good tools, and high-level reading comprehension


Full Valve Body Assembly

There are four primary types of valve bodies to choose from:

Fully Automatic

  • Considered stock
  • Delivers smooth shifting
  • Great for non-performance applications


  • Great for street-and-strip enthusiasts
  • Shifts normally in Drive
  • Offers manual control in low gears (sometimes called “Autostick”)
  • Can typically be installed by DIYers

Full Manual

  • Option for race applications
  • Bypasses all auto shifting
  • Forward and reverse shift patterns are available for most applications
  • Intensive installation in existing transmissions, often requiring removal and disassembly for internal case mods and rotating parts upgrades


  • Drag race only
  • Same features as full manual valve body, but added launch feature
  • Transbrakes allow for launching race cars at higher rpm
  • Hard on internal parts, requiring upgraded transmission internals

Modifying valve bodies presents the opportunity to upgrade other critical transmission components, Pritts said, including bellhousings, transmission cases, torque converters, flexplates, oil pans, and more.