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hambrgr
1985 f250 w/6.9idi no od 1,2,d... speedo ok.. tach works when it wants to
but hard shift is present when tach is operating or not workin.
acting like its a vacum problem vac pump could be shot...
My guess is you have a C6 Trans it uses a K/D rod which is actuated Off the throttle someplace the TV rod will increase pressure to make the shifts harder at WOT it is most likely stuck in the WOT position Look on the left side of the trans at the side of the pan there should be a shift linkage and a flat lever with some sort of rod going up to the engine bay, move this rod up or forward and tie it that way and try a road test
hard shift as in it bangs into gear, or hard shift as in it will not shift unless you let off the throttle??
if it is a bang into gear hard shift, that is normal with the C6. if you adjust the modulator valve for soft shift, you will burn up the trans.
if it is a will not shift till you let off the throttle hard shift, it is most likely a vacuum pump going bad.
the vacuum pump need to supply around 21 inches of vacuum for the trans to shift properly.