Thread: hard shifts
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Old 08-21-2006, 11:12 AM
SD Blue SD Blue is offline
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Join Date: Jun 2004
Location: West of Ft. Worth. TX
Posts: 4,186
Originally Posted by adrenelin500 View Post
Thanks blue , I had no vac at the IP at all, blockage right up by the fuse box was to blame. Any idea how you adjust the modulator... as in how much or little vac it should be set to ,or is it a shoot from the hip kind of thing?
The adjustment of the modulator is in the link that I provided you. The modulator is set according to pump pressures of a particular model. From when I replaced mine, I recall the pressure reading should be 40.

But, just tweaking the modulator is not going to resolve this. You need to ensure the vacuum control valve at the IP is set properly. As reported in that link, if rack movement doesn't coincide with the proper range of vacuum, the shifts will either be rough and too soon or result in flaring.

84 300SD 350K+ miles ( Blue Belle )
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