TH400 shifting late/hard

[Scott Nixon]

Vacuum pump was out so I replaced it.

Replaced the vacuum solonoid on the TH400,
old one was good though. 20 plus inches
of vacuum at the solonoid.

Bypassed the kick-down vacuum bleed-off on
the pump.

Nothing helped. Shifts hard at high rpm.
Used to shift at 15mph/35mph under partial
throttle; now shifts at 25mph/47mph no matter
what.

Tranny was rebuilt 20K miles ago.

Any ideas?

Peace,

Scott Nixon

[Peter J. Bierman]

If you mean the modulator with the solenoid and you get enough vacuum at it, you can try adjusting the screw in the modulator by removing the vacuum hose and turn the screw in the pipe.
Turning in makes it shift harder, tuning out makes it shift softer.
If that does not make a differace the governor might be stuck, so you always need high pressure to shift.
Messuring the oil line pressures might give you more information.

good luck,

Peter