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Fluid control in a 727 pan

Posted By: polyspheric

Fluid control in a 727 pan - 06/16/16 10:38 PM

Perhaps I'm overlooking something obvious, but should we be concerned about uncovering the pump pick-up on high-G acceleration?
When the front wheels come up, the fluid rushes backward and stands up on the back wall of the pan just like in the engine oil pan.
How does this not cause an air bubble to enter the pick-up, which will cause momentary loss of line pressure when that slug of fluid passes through the valve body, etc?

If there's been a prior discussion on this, please point me to it?
Thanks.
Posted By: DARTH V8Я

Re: Fluid control in a 727 pan - 06/16/16 10:45 PM

Always thought there's enough fluid in the pan not to get uncovered short of going upside down.
Posted By: PC-CHARGER

Re: Fluid control in a 727 pan - 06/16/16 11:42 PM

I've seen some fabricated pans that have a rear baffle for just this reason. That combined with a deep pan and extended pickup would minimize the chance of uncovering the pickup.
Posted By: Cab_Burge

Re: Fluid control in a 727 pan - 06/16/16 11:57 PM

Originally Posted By PC-CHARGER
I've seen some fabricated pans that have a rear baffle for just this reason. That combined with a deep pan and extended pickup would minimize the chance of uncovering the pickup.
iagreeI have a older Pro Trans SS/AH 727 with a B&M aluminum deep pan on it that has a baffle welded onto the back side going up to the pickup to keep tranny fluid around the pickup no matter the angle of the motor and trans thumbs scope work I've never done that to a deep Mopar brand steel pan, maybe my cars don't leave hard enough to worry about that confused Maybe I should work
Posted By: polyspheric

Re: Fluid control in a 727 pan - 06/17/16 01:54 AM

Thoughts from Brian P in response to my post at Speed Talk:

"Suspicions (nothing more)
The specified fluid level is high enough, and the orientation of the pick-up is such that the pick-up doesn't pull in air under that situation.
In a drag-race start, the clutches needed for 1st gear are already engaged and the torque converter is already full of fluid, and the lock-up clutch (if there is one) is not going to be engaged at that moment. What it means is that there is actually not much demand for fluid volume at that moment. For the clutches to disengage, not only would the pump have to be sucking air but there would also have to be demand for sufficient fluid at that moment - for example, if the trans controls were commanding one of the other clutches to engage.
By the time the trans controls are commanding some other clutch to engage (demanding fluid), the violent forces of the start aren't present any more."
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