trans problems 1985 300SD
 

ok 1985 300 sd
ive been having random shifting problems. when i get on the pedal hard, "sometimes" ill miss a gear??? usually 3rd or 4th. the car will act like i just threw it in neutral for a sec until i let off the pedal and then it just shifts, no grinding, no really bad noises. Im really kind of concerned. Also the trans shifts hard into 2nd especially when its cold.
Thanks for your help.

Have you checked the level and condition of the fluid?

just for a test,disconnect the wire to the kickdown button located under or say behind the accelerator pedal and see what happens. see if it still does the same thing. i just recently fixed a friends tranny that had different symptoms but a bad kickdown switch makes the tranny have a mind of its own. hth mike

The kickdown switch won't produce flaring, which is the stated symptom of the OP.

The problem is related to wear within the transmission, but, can usually be reduced somewhat by lowering the vacuum to the modulator.

The modulator serves to soften the shifts by extending the shift time, but, if the time is too great, the trans can miss the shift.........a term we call "flaring".

You'll need a Mityvac and some hose and fittings to perform some tests to see what the current vacuum is and then we can adjust it lower.

The firmness of the 1-2 shift is typical on these vehicles. Any adjustments that we do will probably make it a bit worse, unfortunately.

Vacuum is plumbed differently when it is cold. I believe these vehicles have a switchover valve that is controlled by a temp switch. The modulator should get more vacuum when it is cold.