Late Shift To OD

[bccan]

High mileage BRF retrofitted into 70 Cutlass. As far as I know unit is untouched except for a slightly lightened secondary weight on governor.

Normally shifts to OD @ appx 40 mph (light throttle), out of the blue it has decided to wait until appx 60 mph to make the shift the last few times driven. Other shifts are normally timed & normal feel. I reset the TV cable just in case but no change. Any ideas or suggestions?

 

[bccan]

Got car out on highway today. It just doesn't want to make 3-4 shift until 60mph @ "normal" light throttle. It normally was always pretty much exactly @ 40mph until it started this new trend w/ no changes or warning.

It is wired for OD only L/U w/ a Bowler lockup delay - working normally. Locks up appx 8 secs after shifting to OD, unlocks on closed throttle or brake application. Also has a low vac cutoff but I didn't hammer it to double check that. All this depends on trans being in OD to activate any of it so I don't think it is in L/U circuit.

Could it just be a sticky valve? I haven't looked @ circuits so I'm just trying to get ideas before I do any internal exams. If I drop VB I wanna have some direction or idea what to look at/for.

 

[SSedan64]

Hook up a Pr. Gauge & check Line Pr. @1000-1200rpm, Min. & Max. TV cable positions.
There's also a 4th Clutch Pr. port on the Passenger side to the rear of the 2nd/Intermediate Servo, only has Pr. after 3-4 shift.
http://www.extremeautomatics.com/techinfo.html
http://www.jakesperformance.com/TV_Cable_Setup_Info.html

For Valvebody you can check the 3-4 Throttle Valve and 3-4 Shift Valve for sticking/binding.
TV/ThrottleValve & TV Plunger for binding/sticking.