Purpose of the 3-2 downshift solenoid in the 4L60E?
Thread Starter
Staging Lane
Joined: Sep 2018
Posts: 58
Likes: 3
Purpose of the 3-2 downshift solenoid in the 4L60E? So forgive me for being naive but I'm just curious how the 3-2 downshift / TCC PWM lockup solenoid plays into the 4L60E's. The terminology sounds simple enough but there is also solenoid A and B that control what gear the transmission is in and there is a TCC solenoid that controls the lockup.So I'm a little confused how this seemingly dual purpose solenoid controls two different things that are already controlled by other solenoids.
TECH Junkie
Joined: Dec 2012
Posts: 3,620
Likes: 1,331
From: Iowa
it controls the exhaust of the 3/4 clutch.
Solenoid OFF=valve is stroked outboard by spring force=quicker exhaust (typically at low speeds)
Solenoid ON=valve is stroked inboard by AFL (which is then called 3-2 signal fluid after the solenoid) against spring pressure...stroked inboard=slower exhaust. (higher speeds/more load)
This is done to assist shift timing. It helps shift feel for the driver.
It's a very good mod for high horsepower builds to block the 3-2 control inboard...but then you need to alter other hole sizes to get the timing correct.
The 3-2 control and TCC pwm solenoids are NOT the same by the way (at least in most years...i think in 95 the 3-2 was pwm)
In everything 96 and newer, the 3-2 solenoid is just an on-off 3 port solenoid. It may LOOK like the TCC...but it's not the same
Solenoid OFF=valve is stroked outboard by spring force=quicker exhaust (typically at low speeds)
Solenoid ON=valve is stroked inboard by AFL (which is then called 3-2 signal fluid after the solenoid) against spring pressure...stroked inboard=slower exhaust. (higher speeds/more load)
This is done to assist shift timing. It helps shift feel for the driver.
It's a very good mod for high horsepower builds to block the 3-2 control inboard...but then you need to alter other hole sizes to get the timing correct.
The 3-2 control and TCC pwm solenoids are NOT the same by the way (at least in most years...i think in 95 the 3-2 was pwm)
In everything 96 and newer, the 3-2 solenoid is just an on-off 3 port solenoid. It may LOOK like the TCC...but it's not the same
I'll admit, I've never done this before. Never really knew about it...until you mentioned it i few times. If you dont mind, Could you outline how and what you do exactly? What holes to drill, what sixes, how to block it and the location. Unless theres other info on it you could post a link to.
TECH Junkie
Joined: Dec 2012
Posts: 3,620
Likes: 1,331
From: Iowa
As I said before, the cliff notes are that blocking the valve inboard cures a circuit leak, and gives you more control/tuneability over the 3-2 downshift. If you block a checkball hole, you can then also have more control over the band release timing in relation to the 3-4 clutch apply timing...helping give control over the 2-3 upshift.
Here's some notes from another thread I posted in (the checkball hole I'm referring to is 29f...right next to the band release hole):
A. if NOT blocking the 3-2 valve, and you want slightly better than stock shifts, drill .100(3rd feed) and .082 (band release) (dont block the checkball)
B. if NOT blocking and you have a camaro or gto or a truck that you have increased power on, etc..drill .125/.093 (don't block the checkball hole)
C. If blocking the 3-2 valve and using "corvette" servo...drill .135/.100 (block the checkball)
D. If blocking the 3-2 and using a billet servo...droll .145 or .150 and .110 (block the checkball)
I'll Add E...my personal favorite...drill 3rd feed about .140, don't block the checkball hole...block the 3-2...drill the band release hole to about .104
The band release hole really only matters for downshifts UNLESS you're blocking that check ball hole closed...because normally during an upshift the check ball is off its seat and allowing max flow...so then if you block that checkball hole it can affect the 2-3 upshift timing because the oil to release the band is now orificed.
Blocking the checkball and using the "band release" hole to orifice the 3rd accum (which releases the band) fluid does the same job as the sonnax servo checkball capsule plug deal...kindof...That's a whole 'nother rabbit hole to go down
Scenarios A and B drilling the band release hole only changes downshift exhaust speed for the band
Scenarios C and D drilling the band release affects the 3-2 downshift timing AND the 2-3 upshift timing
Scenario E drilling the band release hole only affects the 3-2 downshift timing...I personally have good luck with this method.
Here's some notes from another thread I posted in (the checkball hole I'm referring to is 29f...right next to the band release hole):
A. if NOT blocking the 3-2 valve, and you want slightly better than stock shifts, drill .100(3rd feed) and .082 (band release) (dont block the checkball)
B. if NOT blocking and you have a camaro or gto or a truck that you have increased power on, etc..drill .125/.093 (don't block the checkball hole)
C. If blocking the 3-2 valve and using "corvette" servo...drill .135/.100 (block the checkball)
D. If blocking the 3-2 and using a billet servo...droll .145 or .150 and .110 (block the checkball)
I'll Add E...my personal favorite...drill 3rd feed about .140, don't block the checkball hole...block the 3-2...drill the band release hole to about .104
The band release hole really only matters for downshifts UNLESS you're blocking that check ball hole closed...because normally during an upshift the check ball is off its seat and allowing max flow...so then if you block that checkball hole it can affect the 2-3 upshift timing because the oil to release the band is now orificed.
Blocking the checkball and using the "band release" hole to orifice the 3rd accum (which releases the band) fluid does the same job as the sonnax servo checkball capsule plug deal...kindof...That's a whole 'nother rabbit hole to go down
Scenarios A and B drilling the band release hole only changes downshift exhaust speed for the band
Scenarios C and D drilling the band release affects the 3-2 downshift timing AND the 2-3 upshift timing
Scenario E drilling the band release hole only affects the 3-2 downshift timing...I personally have good luck with this method.
Thread Starter
Staging Lane
Joined: Sep 2018
Posts: 58
Likes: 3
Good info and I appreciate the insight...especially so quickly.
So basically if the 3-2 solenoid is stuck on, it's likely to delay the 3-2 downshift until the pressure on the 3-4 clutch can bleed off? Meanwhile, if it's stuck off, it's more likely to slam into 3rd on the upshift? Or am I way off target?
So basically if the 3-2 solenoid is stuck on, it's likely to delay the 3-2 downshift until the pressure on the 3-4 clutch can bleed off? Meanwhile, if it's stuck off, it's more likely to slam into 3rd on the upshift? Or am I way off target?
