Rebuilt 4L80E slipping in forward

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5,767
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Fort Worth, Texas
Filtered AFL should NOT crossleak into the ENDS of the Shift Valves through the Red area called out by Sonnax!!!

Filtered AFL is Orificed/Metered through the Plate making it 1-2 Signal/"A" Signal & 2-3 Signal/"B" Signal......The Orifices are marked 20/21 for "A" & 20/22 for "B" on the Plate diagram below.
Metering the AFL is very important for proper function of the Shift Valves, I've seen these holes enlarged too much thus causing shift issues because the Valves & Solenoids being flooded with AFL oil.

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5,767
Location
Fort Worth, Texas
To further clarify (I hope)....

The red area called out by Sonnax (20) is fed through the 2 Green rectangles....Then fed through the Case too the 2 Solenoids/Shift Valve Orifices.

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5,767
Location
Fort Worth, Texas
Now.....It's going to leak from (#5) AFL as that's what feeds the AFL Filter at the end of the Manual Valve Bore. Block the #5 bridge across the Shift Valves with your plate if you can.
 

Lindberget

Thread starter
Messages
21
Thanks @clinebarger , clear!!
I got about 13 hg-in when covering #5, putting vacuum to #20. Hard measure as there are a lot of passages to seal of.
That leak should be thru either the filter end plug or the 2-3 shift valve, as I have a o-ringed plug against the manual valve?
Attached a picture of my separator plate, orfice 20/21 and 20/22 looks untouched.
 

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Lindberget

Thread starter
Messages
21
Did some more measurements, see readings in pictures. Opinions?
I have three stops that looks low in the VB.

1,Lo/reverse checkball is at 14hg-in.
2,Reverse checkball at 12
3,Afl filter passage #20/5 at 14 hg-in. If only measuring the #5 channel blocking the filter out it still reads 14. Leak should be by the 2-3 shift valve? How it that assessed?

Could those be my reasons, seems fair according to the Sonnax instruction sheet?

Next challenge, the recommended Sonnax replacement checkball seats does only list for 1995-later fit. I have a 1991 case and VB. Any suggestions?
 

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Messages
5,767
Location
Fort Worth, Texas
Without a known good Valve Body to compare to using YOUR equipment......It's tough to answer your question.

Generally....Valve body wear, Assuming no valves are stuck/sticking.....Will show issues when the unit is hot. I always/100% ream the AFL Bore & use a oversized AFL Valve on Early 4L80E Valve Bodies. But like I already stated, Low AFL pressure will cause a NO 4th or Falling out of 4th HOT long before 2nd gear starts.

Hook the Valve Body or just the Solenoids up to the Controller & make sure it's commanding only Solenoid A ON for 1st gear.
 
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