May 7, 2019 · Disconnect the hose at the modulator with the motor running. The engine rpm should change immediately. Turning out the screw in the modulator will make the shifts earlier and softer.

Year 1964 up This modulator can be used when putting a TH400 behind a blower, turbo or in diesel applications. Requires a cable Part# 400-40MC. Replaces the vacuum modulator with a direct acting valve connected to the throttle.

The TH400 vacuum modulator diagram is an essential tool for understanding and troubleshooting the operation of the TH400 transmission. The TH400, also known as the Turbo 400, is a three-speed automatic transmission that was widely used in vehicles from the 1960s to the 1990s.

Modulator valve leaks are very common on the TH400. Fortunately, they are also very simple to repair. Check it out!For more content visit:instagram.com/burno...

Mar 18, 2010 · Grinding a flat on the mod valve will never eliminate the 3-2 downshift. Its normally done when a manual shift conversion is done or sometimes done with high numeric axle ratio's so that governor oil dosn't drop line pressure as road speed increases.

Sep 18, 2019 · The modulator affects shift firmness, and the shift timing as a "side effect". Modifying the modulator raises the pressures inside the transmission and makes life tougher for the rubber seals and the pump.

This vacuum modulator valve is a must-have for all TH350 and TH400 automatic transmissions. The valve fits into the transmission housing and controls vacuum used for shifting and kick-down functions.

Use Figure 2-20 as a guide to remove the valve body assembly (49) and related components.

Jun 1, 2001 · I am putting a turbo 400 in my car and the I am curious what I need to do about the line to the vacuum modulator on the turbo 400 to keep boost from being an issue. Do I need to just use a check valve in line? Thanks for the help.