200-4R Dual fed Direct: bind vs. flare

PonchoMan

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Jul 5, 2018
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On a 200-4R- When we dual feed the direct clutch if the hydraulics aren’t just right we could have a momentary bind and if we open up #5 third accumulator orifice too much it could lead to a flare. Can anyone explain what’s happening hydraulically? Just trying to picture this: bind- is the direct clutch applying too quick compared to the band release; flare- the band releases before the direct clutch applies. Thanks in advance!
 

mikestertwo

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Sep 13, 2006
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The bind comes from the direct clutch engaging before the band releases. When you dual feed you are doubling the apply surface area of the direct clutch so it takes 1/2 the pressure to engage the clutch. This is the same pressure that releases the band so what happens is the shift timing gets out of sync. I use heavier return springs in the direct clutch plus a heavier return spring in the band servo.
 

PonchoMan

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Jul 5, 2018
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The bind comes from the direct clutch engaging before the band releases. When you dual feed you are doubling the apply surface area of the direct clutch so it takes 1/2 the pressure to engage the clutch. This is the same pressure that releases the band so what happens is the shift timing gets out of sync. I use heavier return springs in the direct clutch plus a heavier return spring in the band servo.
Thanks! Double the surface area so half the pressure applies the direct, totally missed that, makes sense! I upgraded the direct from a 10 spring to 16 and also changed the servo retract with the heavier higher rate spring Chris had at CK. I haven’t run the trans yet? And the TCI manual VB may change some of this, guess I’ll see once I finish installing the trans. I’m supposing the the flare could be the opposite then; band releasing way before the direct clutch applies. Thanks again!
 

TexasT

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Sep 10, 2002
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I doubt you will get the band to release that quickly. The flare is usually from the direct clutches slipping and not applying quick enough.

Dual feed is a great mod but it applies it hard and quick so the billet shaft FWD drum is pretty much a requirement.
 
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PonchoMan

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I’ve been studying the hydraulic diagrams trying to determine if this changes at all in manual vs automatic. Seems like the same scenario to me.
 

TexasT

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I'm not a fan of the constant pressure vb. Those pump components aren't exactly robust in the first place and then subject them to high pressure(usually even more than the top pressure gm designed them for) just seems like rolling the dice. Doing twice the max pressure sometimes when the car needs it at wot is hard enough on those pump parts to me.
 

PonchoMan

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Jul 5, 2018
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I'm not a fan of the constant pressure vb. Those pump components aren't exactly robust in the first place and then subject them to high pressure(usually even more than the top pressure gm designed them for) just seems like rolling the dice. Doing twice the max pressure sometimes when the car needs it at wot is hard enough on those pump parts to me.
Yeah I did what I could to beef it up with a billet rotor, and hardened rings, etc... but I agree. I expect it will be the Achilles heel in this build.
 
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