Pressure with vacuum modulator???
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10 Second Club
Joined: Apr 2002
Posts: 1,755
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From: Cincinnati, Ohio
Pressure with vacuum modulator??? Internal trans. work is not my thing so please bear with me. I had to rebuild my trans.. It already has all the good hard parts and clutches & bands. I originally bought the trans. from a sponsor but had a local guy do the rebuild. I would have to say that my pressure is probably too low. With the modulator vacuum line connected it shifts way soft like a Cadillac. Disconnected it does feel firm. I have not gotten on it to cause any slip. I think if I get the pressure right I should be good. What should the pressure be with & without vacuum? What gear do you check it in? Does the pressure vary from gear to gear? Any help is greatly appreciated.
Originally Posted by 2001WS6Vert
Internal trans. work is not my thing so please bear with me. I had to rebuild my trans.. It already has all the good hard parts and clutches & bands. I originally bought the trans. from a sponsor but had a local guy do the rebuild. I would have to say that my pressure is probably too low. With the modulator vacuum line connected it shifts way soft like a Cadillac. Disconnected it does feel firm. I have not gotten on it to cause any slip. I think if I get the pressure right I should be good. What should the pressure be with & without vacuum? What gear do you check it in? Does the pressure vary from gear to gear? Any help is greatly appreciated.
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Joined: Apr 2004
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With the modulator connected, it is supposed to make light throttle shifts smooth, with more throttle the vacuum goes down & the line pressure goes up accordingly. At WOT the vacuum is near zero, thereby giving you maximum line pressure. DO NOT drive it with the vacuum line disconnected, as this gives maximum line pressure all the time, and can be hard on the front pump. When I build these units I want the smooth part throttle shifts, and the shifts getting progressively firmer with more throttle. Reconnect the modulator, and go for a test drive to see what happens? The pressure at idle should be 75-90 lbs., & at WOT about 220-235 lbs.
how do you feel about disconnecting the vacuum line for boosted cars at the track ONLY? Just thought it would kind of ctake the check vavle and all out of the loop when you really need the line pressure
