Band release hole
Band release hole On a 4l60e, why is it that when the 3-2 valve is blocked the band release hole needs to be enlarged? If we are potentially getting rid of leaks wouldn't it not need to he enlarged? Is it due to the fact that now the circuit has to travel a longer path? Or it's mostly affected by 2-3 hole size, so proportionally the BR hole is enlarged to time it right?
Thanks.
P.s. does anyone have a VB diagram with all the checkballs with their respective number and function?
Thanks.
P.s. does anyone have a VB diagram with all the checkballs with their respective number and function?
Last edited by subeone; Dec 27, 2022 at 12:57 PM.
TECH Junkie
Joined: Jun 2008
Posts: 3,202
Likes: 1,390
From: Nitro Alley
The 3-2 Control Valve is a bypass circuit.
It bypasses the #12 Orifice (Band Release Hole) and #2 Check-Ball (Band Release Check-Ball).
We want to eliminate this Bypass and use the Band Release Hole to control the Timing of the Band being release with the Apply of the 3-4 Clutch...
This makes the 2-3 Up-Shift.
Below is a modified Hydraulic Diagram that I made to show this:
Fluid needs to go from the 2-3 Shift Valve to both the 2-4 Servo (to push-off/ release the Band) and the 3-4 Clutch.
It bypasses the #12 Orifice (Band Release Hole) and #2 Check-Ball (Band Release Check-Ball).
We want to eliminate this Bypass and use the Band Release Hole to control the Timing of the Band being release with the Apply of the 3-4 Clutch...
This makes the 2-3 Up-Shift.
Below is a modified Hydraulic Diagram that I made to show this:
The diagram makes perfect sense. So without blocking the valve, the checkball is completely bypassed or we have parallel flow? I would expect to have flow through checkball AND the bypass, correct?
If the valve were to be left, the band release hole shouldn't be messed with to properly time band release, correct?
The sole purpose is to eliminate potential leaks? If the valve is not leaking (using a vacuumtest per se), am I doing my trans a disservice by not blocking it?
Or for high performance application it is absolutely necessary because it's inherent to increase 2-3 hole size, therefore band release needs to be timed accordingly?
Sorry for all the questions, just curious as to why something is being done.
Edit*If the sole purpose is to eliminate leaks, isn't there some sort of reamer with oversize valve kit so we don't have to be guessing at band release timing?
If the valve were to be left, the band release hole shouldn't be messed with to properly time band release, correct?
The sole purpose is to eliminate potential leaks? If the valve is not leaking (using a vacuumtest per se), am I doing my trans a disservice by not blocking it?
Or for high performance application it is absolutely necessary because it's inherent to increase 2-3 hole size, therefore band release needs to be timed accordingly?
Sorry for all the questions, just curious as to why something is being done.
Edit*If the sole purpose is to eliminate leaks, isn't there some sort of reamer with oversize valve kit so we don't have to be guessing at band release timing?
Last edited by subeone; Dec 27, 2022 at 05:48 PM.
TECH Junkie
Joined: Jun 2008
Posts: 3,202
Likes: 1,390
From: Nitro Alley
The diagram makes perfect sense. So without blocking the valve, the checkball is completely bypassed or we have parallel flow? I would expect to have flow through checkball AND the bypass, correct?
If the valve were to be left, the band release hole shouldn't be messed with to properly time band release, correct?
The sole purpose is to eliminate potential leaks? If the valve is not leaking (using a vacuumtest per se), am I doing my trans a disservice by not blocking it?
Or for high performance application it is absolutely necessary because it's inherent to increase 2-3 hole size, therefore band release needs to be timed accordingly?
Sorry for all the questions, just curious as to why something is being done.
Edit*If the sole purpose is to eliminate leaks, isn't there some sort of reamer with oversize valve kit so we don't have to be guessing at band release timing?
If the valve were to be left, the band release hole shouldn't be messed with to properly time band release, correct?
The sole purpose is to eliminate potential leaks? If the valve is not leaking (using a vacuumtest per se), am I doing my trans a disservice by not blocking it?
Or for high performance application it is absolutely necessary because it's inherent to increase 2-3 hole size, therefore band release needs to be timed accordingly?
Sorry for all the questions, just curious as to why something is being done.
Edit*If the sole purpose is to eliminate leaks, isn't there some sort of reamer with oversize valve kit so we don't have to be guessing at band release timing?
There is parallel flow when the Valve is in the Open Position (We do not want this to occur, it changes the Timing of the Band Release).
When the Valve is in the Closed Position, flow is the same as if the Valve is Blocked.
There can be some Fluid leaked at any worn Valve...
Generally a Leak is more common at the 3-2 Down-Shift Valve, Not the 3-2 Control Valve.
We block the 3-2 Control Valve to eliminate a Variable in the Timing of the 2-3 Shift.
When the Valve is Blocked, we control the timing of the Band Release via the Hole.
