Need help with autotransmission on 1987 300D (trans # 722.317). Rough, hard shifts going up and clunks on downshift.

Have check all the vacuum lines, and they are good. Have checked vacuum going into vacuum amplifier (appears good at 15-20 inches) and coming out to trans (appears good at 5-6 inches). Did vacuum test on transmission modulator valve and vacuum line that goes from vacuum amp to the modulator, and this is good. Several articles I looked at say that the vacuum should drop to zero when you open the throttle--mine stays constant going in & coming out of the vacuum amp. Have tried to adjust the modulator valve by trial & error (turned clockwise to soften shift), but nothing has worked yet. Any suggestions?

fgreynolds

Welcome to the forum-

I believe that a clockwise adjustment will make the trans shift more firmly.

Another posting on this site said to replace the rubber tube in between the vac. mod and the plastic line coming down. Looked find by was hard and cracked.

When was the trans serviced last?

Keep us posted,

Haasman

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