Turbo 400 experts please step in....

ss3011 · 10-22-2018, 07:16 PM

Some how I thought your post was to set the shift points at WOT . It is harder to set the part throttle shift points . The modulator system basically makes a pressure to tell the transmission what load is on the engine . This is based on manifold vacuum . The lower the vacuum the higher this modulator pressure would be . So if you have an engine with high vacuum at idle , and you lightly drive away from a stop , you get a very low modulator pressure and therefore a early shift point . A hot rod engine might have a fairly low idle vacuum and if you did that light throttle drive away , you might get a delayed shift . So most hot rodders put a high stall converter in place of the stock tight converter , and what happens is the manifold vacuum is much higher than it would normally be , creating a low modulator pressure and an early shift . Most of the newer transmissions that are built now have electronically controlled shift patterns . They don't shift based on manifold vacuum . Before electronics there were cable controlled transmissions , like the 200 THM or 700-R4 . There were many different modulators to deal with different engines , with different manifold vacuums , but not anymore . The adjustable modulators are really not for you to adjust , but to set the modulator to a factor specification . There is not much you can do with your current vacuum modulator system . One thing you might try is a B&M Modulink , which basically converts the vacuum modulator to a throttle cable controlled modulator . I worked on a similar system for the Hummer , which was a diesel , so no manifold vacuum .

10-22-2018, 07:16 PM	#10
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 885 Likes: 63 Liked 221 Times in 102 Posts	Re: Turbo 400 experts please step in.... Some how I thought your post was to set the shift points at WOT . It is harder to set the part throttle shift points . The modulator system basically makes a pressure to tell the transmission what load is on the engine . This is based on manifold vacuum . The lower the vacuum the higher this modulator pressure would be . So if you have an engine with high vacuum at idle , and you lightly drive away from a stop , you get a very low modulator pressure and therefore a early shift point . A hot rod engine might have a fairly low idle vacuum and if you did that light throttle drive away , you might get a delayed shift . So most hot rodders put a high stall converter in place of the stock tight converter , and what happens is the manifold vacuum is much higher than it would normally be , creating a low modulator pressure and an early shift . Most of the newer transmissions that are built now have electronically controlled shift patterns . They don't shift based on manifold vacuum . Before electronics there were cable controlled transmissions , like the 200 THM or 700-R4 . There were many different modulators to deal with different engines , with different manifold vacuums , but not anymore . The adjustable modulators are really not for you to adjust , but to set the modulator to a factor specification . There is not much you can do with your current vacuum modulator system . One thing you might try is a B&M Modulink , which basically converts the vacuum modulator to a throttle cable controlled modulator . I worked on a similar system for the Hummer , which was a diesel , so no manifold vacuum .