C6 Vacuum Modulator: Which One??
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Joined: Dec 2003
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C6 Vacuum Modulator: Which One??
Hi All, I have a 1987 E350 w/460 and 4BBL. It is shifting very early under moderate acceleration and I decided to replace the modulator (first I adjusted the screw in the vacuum port fully in, with a small amojunt of success). Anyway, The modulator I had was a green stripe type. I replaced it with another green stripe. The new one is only slightly better if at all. My question is: What do the color stripes on the various modulators mean? There are greem, purple, black, brown,... Presumably, the stripes indicate a different shifting characteristic. Does anyone know the specifics? Is there a modulator that would make my shifts happen later? Thanks for any info.
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Joined: Mar 2003
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Check at bulkparts.com for a selection. You turn the modulator screw in (clockwise) to place more preload on the internal diaphragm, making it require more vacuum to activate the modulator valve = higher shift point.
The black stripe version will give you the highest shift point, then followed by purple, green, and brown I believe. The rod the connects the modulator to the valve can also be trimmed to shorten the shifts - that can be sort of trial and error, though.
Bear in mind that the shift timing may actually be normal for your power combination. If it shifts firmly under moderate to heavy throttle, you've got a normally acting transmission. The modulator can only control it to a point, the rest is within the valve body itself. If you decide to put a shift kit in it, I recommend a Transgo kit.
The black stripe version will give you the highest shift point, then followed by purple, green, and brown I believe. The rod the connects the modulator to the valve can also be trimmed to shorten the shifts - that can be sort of trial and error, though.
Bear in mind that the shift timing may actually be normal for your power combination. If it shifts firmly under moderate to heavy throttle, you've got a normally acting transmission. The modulator can only control it to a point, the rest is within the valve body itself. If you decide to put a shift kit in it, I recommend a Transgo kit.
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