Lock up circuit application

AHall

AHall

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Joined
Apr 2, 2007
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On a 47s and 48s is the lock up circuit accomplished by sending pressure or cutting pressure?
 
Lockup solenoid closes when a ground is allied, pressure is trapped and builds up against valve and it switches sending pressure to the lockup circuit.


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So the actual engagement and applied force keeping the Tcc locked is from a fluid passage? Is this pressure value the same as line pressure?
 
mathews8pt said:
Lockup solenoid closes when a ground is allied, pressure is trapped and builds up against valve and it switches sending pressure to the lockup circuit.


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Click to expand...

Lockup happens after it releases pressure, that why drilling the hole out bigger in the divider plate makes lock more harsh. I don't know why its only letting me post with his quote.
 
AHall said:
So the actual engagement and applied force keeping the Tcc locked is from a fluid passage? Is this pressure value the same as line pressure?
Click to expand...


Yea you have line pressure applying a piston in the TC, which holds the lockup clutches together.


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jasonc said:
Lockup happens after it releases pressure, that why drilling the hole out bigger in the divider plate makes lock more harsh. I don't know why its only letting me post with his quote.
Click to expand...


Releases pressure from what?


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Well those two statements contridict each other correct?
 
AHall said:
Well those two statements contridict each other correct?
Click to expand...


I wasn't sure which part of the circuit you were talking about.

If you are just wondering how the clutch is held together in the TC it's just line pressure applied by the valve body. It is activated by the lockup solenoid closing when a ground is applied to the circuit.


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My purpose is to see what applies pressure to the Tcc. A mechanical function vs actual line pressure. I'm curious if the 48s and the 4l80e use the same method. I was told by some builders the 4l80e applies the clutch by cutting the feed pressure. This allows the mechanical force to overcome and lockup.
 
Is the 4l80e the same PWM strategy as the 4l60e that doesn't fully apply lockup ever? I don't know them well enough to say, but I thought from 98+ all of the 4l?0e series ran the solenoids at less than 100%.
 
As far as i know the PWM feature was only to allow a smoother lockup with a little slip on the way in. I recently read a little more on the gm transmissions using 1-3 solenoids to control the lockup circuit. 4l80 using just 1.
 
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