200 4r pressure problem

[hootowl]

What causes line pressure to be good for part throttle 1-2 shifts but go way down at 1/2 throttle or higher shifts? This is a rebuild with Alto clutches throughout, an Art Carr shift kit, 10 vane pump, and hardened stator. This problem started about 2 weeks before the rebuild. The original band was burned and the 1-2 accumulator had a broken spring. Nothing that's been done so far has corrected the 1-2 shift problem. Any help would be greatly appreciated.

Mel

87GN, 13.23, 104.5, stock turbo and intercooler, SMT alky, 20 psi. Feels stronger than my stab n' steer has given so far.

 

[77 cruiser]

How's the fluis level? Filter could be sucking air. Is the filter pushed to the bottom of the pan by the clip on the VB?
Pump slide spring could be weak or broken.

 

[hootowl]

Thanks for the reply. Fluid level is good and the filter is ok. The pump was changed from the stock 7 vane to a 10 vane. The sloppy shift symptom was there with the 7 vane pump and still there with the 10 vane pump. The static pressure in Park with max TV is high at about 300psi and drops to about 90 at half throttle (spring mods that will be reversed to bring max down to 240). However, the problem was the same before the pressure was boosted.

Mel

87GN, 13.23, 104.5, stock turbo and intercooler, SMT alky, 20 psi. Feels stronger than my stab n' steer has given so far.