Auto box A727 don't down shift 2-1

[Steveh]

Hi guys.

My uncle has recently had his a727 rebuilt with a shift kit fitted. Now the box doesn't't down shift 2-1. When it's in 1st gear it works great . The v/b has a ball in the 1-2control vale stopping it moving. I removed that and no better. There is also a steel rod where the spring behing the shuttle valve was.   Please help.

[John_Kunkel]

Welcome to the board.

The problem is either in the governor or a stuck shift valve in the valve body. To isolate the governor, hook up a test gauge to the governor test port on the tailhousing...with the  shifter in Drive and the rear wheels stopped, the governor pressure should not exceed 2 psi. If that's OK the problem is a stuck 1-2 shift valve.

[Steveh]

Thanks for the reply. I have already stripped the v/b and the shift valve falls under its own weight. The 2-1 control valve had a ball stopping it moving. Would the governor also be faulty on 3-2?

[John_Kunkel]

The ball in the 1-2 shift control valve and the blocker rod in the accumulator are common mods, neither will prevent down shifting. The accumulator blocker rods cancels out the operation of the 1-2 shift control valve so the two mods together are redundant.

If the governor valve is sticky it will allow a little bit of governor pressure to remain when the car comes to a full stop (should be 0-2 psi)...enough to prevent the weak shift valve return spring from closing the valve. This won't affect the 2-3 shift.

[Steveh]

Ok makes sense. Your help is much appreciated. Will check the governor.