Current symptoms are hard shifts from 1-2 & from 2-3. 3-4 is very acceptable. It is a little hard when moving from Park into Drive and sometimes Drive to Reverse. Shift points are ~ what is listed in various trans manuals.

I will go back and confirm current vacuum pressure and that the modulator still holds before changing anything.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

Step 1:

Remove modulator line from T above VCV.


Step 2:

Connect Mityvac to modulator line.



Step 3:


Pump up Mityvac and see if it holds vacuum. If it does not, you found your problem at the modulator............either cap or modulator valve itself.



Step 4:


If Mityvac hold vacuum, route Mityvac into cabin and take vehicle for a drive with Mityvac pumped up to 18" or so. See if hard shifts disappear.


Step 5:

If hard shifts become very soft, some work is necessary to the vacuum system.


Step 6:

If hard shifts do not change with 18" vacuum, the modulator must be replaced.



See, I don't need any baseline data that verifies the various specifications for modulator pressure or vacuum to take you down a path of correction for your issue and I am definitely not urinating off the high side of a sailboat.