Problems with Running a 4L80E at Full Line Pressure?
Thread Starter
Staging Lane
Joined: Feb 2019
Posts: 79
Likes: 5
From: Houston, Texas
Problems with Running a 4L80E at Full Line Pressure? Hey guys,
I've got a 4L80E swapped into my 94 Bird with a Full Manual wiring harness that I fabbed up out of a spare conversion harness. I had originally intended for the 4L80E to be controlled by the PCM, but I could never get it to shift/downshift correctly, so I went the "guarenteed to work" route and converted to full manual control with a toggle switch for the TCC. One possible problem with doing this that I've read about (at least with 4L60E's) is that there is no actuation for the line pressure control solenoid, it's running at full pressure all the time. My question is if there are any reliability concerns with doing this? It's a bone stock 4L80E out of an 04 Silverado 2500 HD. I intend to eventually do a rebuild with a shift kit and a higher stall converter, but that's not in the budget atm. Simply put, should I be really concerned about getting the tranny equipped with a proper automatic control setup?
I've got a 4L80E swapped into my 94 Bird with a Full Manual wiring harness that I fabbed up out of a spare conversion harness. I had originally intended for the 4L80E to be controlled by the PCM, but I could never get it to shift/downshift correctly, so I went the "guarenteed to work" route and converted to full manual control with a toggle switch for the TCC. One possible problem with doing this that I've read about (at least with 4L60E's) is that there is no actuation for the line pressure control solenoid, it's running at full pressure all the time. My question is if there are any reliability concerns with doing this? It's a bone stock 4L80E out of an 04 Silverado 2500 HD. I intend to eventually do a rebuild with a shift kit and a higher stall converter, but that's not in the budget atm. Simply put, should I be really concerned about getting the tranny equipped with a proper automatic control setup?
TECH Junkie
Joined: Jun 2008
Posts: 3,202
Likes: 1,390
From: Nitro Alley
There is no issue at all.
Some small modifications would be beneficial...
Ensure Pump clearances are acceptable.
Vent Reverse-Boost Circuit to exhaust/ void.
Drill a Line to Lube Bleed-Orifice.
Pressure Balance the Outer Pump-Gear.
Target 165 PSI via Pressure Regulator Valve Spring height/ rate.
Waved Steel in the Forward and Intermediate Clutch-Packs.
Waved Intermediate Frictions from a THM400 work nicely to help the Intermediate-Sprag live a longer life.
Second Accumulator active... Installing a longer/ firmer Spring in the Accumulator Valve-Train can soften the 1-2 Shift.
Dual-Feed the Direct Clutch... this will provide an accumulator affect for the 2-3 Shift.
Block-Off 3rd and 4th Accumulators.
Some small modifications would be beneficial...
Ensure Pump clearances are acceptable.
Vent Reverse-Boost Circuit to exhaust/ void.
Drill a Line to Lube Bleed-Orifice.
Pressure Balance the Outer Pump-Gear.
Target 165 PSI via Pressure Regulator Valve Spring height/ rate.
Waved Steel in the Forward and Intermediate Clutch-Packs.
Waved Intermediate Frictions from a THM400 work nicely to help the Intermediate-Sprag live a longer life.
Second Accumulator active... Installing a longer/ firmer Spring in the Accumulator Valve-Train can soften the 1-2 Shift.
Dual-Feed the Direct Clutch... this will provide an accumulator affect for the 2-3 Shift.
Block-Off 3rd and 4th Accumulators.
TECH Junkie
Joined: Jun 2008
Posts: 3,202
Likes: 1,390
From: Nitro Alley
TECH Junkie
Joined: Jun 2008
Posts: 3,202
Likes: 1,390
From: Nitro Alley
BTW...
There appears to be some popular YouTube Channel, called Precision Transmissions.
I beg all of you... Please do not watch that crap unless it is for a joke.
I know many of you are interested in Transmission information... but that is the wrong place to get it.
I just got an E-mail from someone trying to argue that the 4L60E has a "Fourth Accumulator" in the Valve-Body; NOT Three Accumulators.
I told the individual, that the 4L60E does have Four Accumulators, but that none were in the Valve-Body.
(Yes, I know that the Forward Accumulator is in the Valve-Body casting... but it is not not what he meant.)
He tells me, that some Guys from Precision Transmissions had a video explaining the Fourth Accumulator.
I told the individual that he is referring to the Accumulator Valve-Train that dictate the operation of the 1-2 and 3-4 Accumulators.
And Finally that there was a 2-3 Accumulator made-up of part of the Intermediate Servo assembly...
and that the Four Accumulators are Forward, 1-2, 2-3, 3-4.
I feel like I could make a YouTube Video stating that the federal Government decided that Taxes never need to be paid again!
...and that people would believe me, just because someone said it in a YouTube Video!!!
There appears to be some popular YouTube Channel, called Precision Transmissions.
I beg all of you... Please do not watch that crap unless it is for a joke.
I know many of you are interested in Transmission information... but that is the wrong place to get it.
I just got an E-mail from someone trying to argue that the 4L60E has a "Fourth Accumulator" in the Valve-Body; NOT Three Accumulators.
I told the individual, that the 4L60E does have Four Accumulators, but that none were in the Valve-Body.
(Yes, I know that the Forward Accumulator is in the Valve-Body casting... but it is not not what he meant.)
He tells me, that some Guys from Precision Transmissions had a video explaining the Fourth Accumulator.
I told the individual that he is referring to the Accumulator Valve-Train that dictate the operation of the 1-2 and 3-4 Accumulators.
And Finally that there was a 2-3 Accumulator made-up of part of the Intermediate Servo assembly...
and that the Four Accumulators are Forward, 1-2, 2-3, 3-4.
I feel like I could make a YouTube Video stating that the federal Government decided that Taxes never need to be paid again!
...and that people would believe me, just because someone said it in a YouTube Video!!!
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I have also heard that leaving some number of the 12 IM piston return springs out softens its apply. I have not tried this.
I get the occasional customer who insists he will need a 1200hp capable transmission, put a very tight converter in it and then complain about harsh 1-2 shifts. It would be nice to have a valve body solution instead of getting into the pump.
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Verdad Gallardo TECH Junkie
Joined: Jun 2008
Posts: 3,202
Likes: 1,390
From: Nitro Alley
I have read that thread, I was just curious what you were using for a spring in the accumulator valve to get a softer 1-2
I have also heard that leaving some number of the 12 IM piston return springs out softens its apply. I have not tried this.
I get the occasional customer who insists he will need a 1200hp capable transmission, put a very tight converter in it and then complain about harsh 1-2 shifts. It would be nice to have a valve body solution instead of getting into the pump.
I have also heard that leaving some number of the 12 IM piston return springs out softens its apply. I have not tried this.
I get the occasional customer who insists he will need a 1200hp capable transmission, put a very tight converter in it and then complain about harsh 1-2 shifts. It would be nice to have a valve body solution instead of getting into the pump.
I have a ridiculous amount of Valve-Body Springs from Cores.
I know that most people through-away unused stock parts from cores...
But I try to keep a small amount of everything; as you never know if some part could be used for something different.
Example: The different versions of the THM400/ 3L80 Accumulator Valve-Train Springs are often thrown-away...
I have kept a bunch of these different Springs.
Rarely, when I do want a Firmer Accumulator Valve Spring for the 4L80E... I use one from the THM400 (I think so anyway).
Regarding the removal of Intermediate Clutch Piston Return-Springs (or lighter Springs)...
I do NOT like this; as partial apply of the Piston often occurs as Pressure builds under the Piston.
For the 4L80E Intermediate Piston in particular...
I only use all 12 Springs, and would even use slightly firmer Springs (and a THM400 Retainer) when available.