It was brought to my attention that there may be some interest in discussing the 4L80E Lubrication-Circuit...
And its changes from the Early System (1991 - 1996) to the Late System (1997 - 2011).

I would also like to discuss the Lubrication-Circuit of the THM400/ 3L80 Transmission; as we (GM) designed the 4L80E mostly from the THM400/ 3L80.

My last two threads did not gain much interest...
So I would first like to see who here might be interested in this topic before I spend a few days searching for diagrams, and making new diagrams.

Please reply to this Post if you are interested in this topic.

 

I’d be very interested.

 

There definitely is.

I think there are a lot of guys like me with plenty of interest, we just have so much to learn, we just read, we don't respond with a post...


Again, very interested.

 

i am always the curious type....even if i dont currently have a 4L80E....so keep the educational stuff coming !

 

I think plenty of guys have read your other posts. "reads" counter keeps going up.
not many reply. That's OK
This seems like a fun topic

 

Very interested!

 

Vortec I have some good pictures and info on improving the lube circuits in both units.
But I think it would be best if we layout How they work...why the changes were made...and how/why the modifications improve lubrication to both early and late

 

I thought it was a VERY informational topic, but I just dont have much to add to it as im still learning myself like others. But that info helps us understand more clear is most ways.

Yes, even though I havnt been through an 80E platform, I would like to know any information as I can for when I do.

The two things I do know about the lube circuit is the early the cooler parts are at the front and the lube goes through the middle of the shafts. The later one port moved to the rear and takes a longer fitting to reach the center support and the lube goes through the bushings if I remember right? Main thing I know is on the late ones dont put a short fitting in the rear lube hole!

 

Okay, I'll get to work.

 

I'll will definitely like more pictures! Please sent them over.

 

To start off, the 4L80E was designed essentially as a THM400/ 3L80 transmission that has had two more clutch sets added for OverDrive.
These are the OverDrive clutch for 4th-Gear...
And the OverRun clutch for engine-braking (particularly for 3rd-Gear since the THM400 has no ability to have engine-braking in 3rd-Gear).

From the Forward clutch back to the Output-Shaft; the 4L80E is essentially like the THM400/ 3L80.
Here are the major-assemblies of the 4L80E:



As far as the Major-Assemblies go, the Pump (in White, to the right of the Green Torque-Converter), the OverDrive Clutch assembly (in White, to the right of the Pump), the OverRun Clutch assembly (in Blue, to the right of the OverDrive Clutch assembly), the OverDrive Carrier/ Planet (in Pink, to the right of the OverRun Clutch assembly), and the OverDrive Ring-Gear on the Forward Clutch-Drum (in Yellow, to the right of the OverDrive Carrier/ Planet) are the majority of the components that differ from the THM400/ 3L80 transmission.





The 4L80E components from the Forward Clutch back to the Output-Shaft are essentially like the THM400/ 3L80 components.
Here is a partial cut-away image of the THM400/ 3L80E.
Notice that there is no OverDrive and OverRun components.
The only major assemblies to the left of the Forward Clutch assembly are the Pump assembly and the Torque-Converter.
Sorry for the black and white image:




In the THM400/ 3L80, the Lube-Oil will enter the case via the return cooler-line (as Cooler-Return Oil)...



Shown above is a THM400 Case. The Cooler-Fittings are both together, near the Pump assembly, on the Passenger-Side. (Shown with Red plugs installed in the above image).
The image below shows a closer look at the location of the Cooler-Fittings (AN style, Black fittings installed):




From the Cooler return fitting; Lube-Oil will enter the Pump at the Pump-Flange, then pass from the Pump to a passage in-towards the Stator-Support Tube (becoming Lube-Oil), then exiting via a passage behind the rear bushing inside the Stator-Support Tube.
Lube-Oil will pass from the rear of the Stator-Support Tube to the Forward Clutch-Drum, then pass throughout the Forward Clutch-Drum (and the Direct Clutch-Drum), and then enter the front of the HOLLOW Intermediate-Shaft.




Imagine that the image above of the 4L80E is an image of the THM400/ 3L80.
Notice the Green (HOLLOW) Intermediate-Shaft...
Imagine the THM400/ 3L80E, Lube-Oil would enter a hole in the very front of the Green (HOLLOW) Intermediate-Shaft.

The THM400 Lube-Circuit passes through (INSIDE) the (HOLLOW) Intermediate-Shaft, and lubricate the rest of the Gear-Train, Sun-Gear Shaft, Center-Support, and Intermediate Clutch assembly via passages/ holes in the Intermediate-Shaft, Sun-Gear Shaft, Sun-Gear, Etc...

The Lube-Circuit will end at the Output-Shaft/ Case-Bushing.
Two lube-holes in the Output-Shaft allow the Lube-Oil to pass from inside the (HOLLOW) Intermediate-Shaft, into the Output-Shaft, and out to the Case-Bushing.




The image above shows a pocket inside the Output-Shaft that will fill with Lube-Oil from the back/ end of the (HOLLOW) Intermediate-Shaft.




Lube-Oil passes from the pocket in the Output-Shaft, through two lube holes (one hole is visible in the image above) into the Case-Bushing.

 

I will now start to get into the 4L80E Lube-Circuit/ System.
There are Two variants of the Lube-Circuit...
1991 - 1996 is the First/ Original version of the 4L80E Lube-Circuit...
and 1997 - 2011 is the Second version of the 4L80E Lube-Circuit.

The THM400/ 3L80 was able to feed Lube-Oil from the FRONT of the (HOLLOW) Intermediate-Shaft as shown in my last post.
This was possible because the Pump/ Stator-Support Tube and the Forward-Clutch assembly were the ONLY components in front of the (HOLLOW) Intermediate-Shaft.

The Lubrication-Circuit for the THM400/ 3L80 was a very successful design, and it has been tried-and-true since 1964.
This system did not cause problems with the THM400...
Except some will argue that the Lube-Circuit is flawed, causing thrust issues that could wear-out the Main Thrust-bearing of an engine.
I am not looking to debate this here or share my thoughts on this, as I do not wish to start arguments/ debates.

Like the THM400/ 3L80; the EARLY-4L80E also has both of the Cooler-Fittings together, near the Pump assembly, on the Passenger-Side.
Shown in the image below with Red plugs installed in the Cooler-Fittings:


Due to the success of the THM400/ 3L80, we (GM Engineers) wanted to apply this Lube-Circuit to the 4L80E as much as possible.
This was Not however entirely possible...
The 4L80E has many more components ahead/ in front of the Intermediate-Shaft.
The OverDrive-Clutch assembly, the OverRun-Clutch assembly, and the OverDrive-Carrier/ Planet are all in front of the Forward-Clutch assembly...
and behind the Pump assembly.

The complexity of having these additional parts made it so that the Lube-Circuit from the THM400/ 3L80 could not be copied-over to the EARLY-4L80E.
We (GM Engineers) had to divide-up the Lube-Circuit into two separate sections (this is regarding the EARLY-4L80E ONLY).
Both sections are shown in the image below:




Lube-Oil is shown in RED in the image above.
We will now be discussing the EARLY-4L80E until I state otherwise.

In the First of Two Lube-Circuit sections, Lube-Oil enters the transmission via a cooler-line and into the Pump assembly (just as the THM400/ 3L80 as Cooler-Return Oil).
Afterwards Lube-Oil will enter the OverRun-Clutch Assembly to lubricate the OverRun and OverDrive sections of the transmission.
The Lube-Oil passage can be seen on the OverRun Clutch-Drum in the image below:




The Red-Arrow in the image points to the Lube passage.
Lube-Oil leaves the back of the Pump/ Stator-Support Tube, then enters the front-facing side of the OverRun Clutch-Drum...
and the passing through the passage shown on the rear-facing side of the drum.

This is One of Two Lube-Circuit sections, and again, it lubricates the OverDrive and OverRun sections of the 4L80E transmission.

In the Second of the Two sections, Lube-Oil from the Pump assembly will pass through a passage into the Valve-Body, then into a long pipe, from the front of the Valve-Body all the way to the Case-Bushing.
Look at the Image below, for a second time... Pay attention to the "Lube-Pipe" in the Oil-Pan area, below the Valve-Body:



Now that Lube-Oil has been directed to the Case-Bushing, Lube oil will of course lubricate the Case-Bushing and then go into the Output-Shaft via two holes.
The same two lube-holes that we looked at on the THM400/ 3L80 Output-Shaft. Shown again below:




Now that Lube-Oil has entered the Output-Shaft, it will enter the rear/ back of the (HOLLOW) Intermediate-Shaft.
This is the Opposite from the THM400/ 3L80 which has the Lube-Oil enter the Front of the (HOLLOW) Intermediate-Shaft and travel Rearward.
The 4L80E has the Lube-Oil enter the Rear of the (HOLLOW) Intermediate-Shaft and travel Forwards.

Once Lube-Oil has entered the Rear of the (HOLLOW) Intermediate-Shaft it lubricates the Gear-Train and the remainder of the components, just as the THM400/ 3L80 did...
But in the opposite order/ direction.
This Lube-Circuit will continue Forwards until reaching the Forward-Clutch assembly and Stopping as it Lubricates there.
Also once the Lube-Oil enters the Case-Bushing from the Lube-Pipe...
Lube-Oil will continue to travel Rearward into a passage inside the Tail-Shaft Housing to the Tail-Shaft Bushing (Two Wheel-Drive models ONLY).
Just as pressurized Lube-Oil will lubricate the Case-Bushing... it will do the same for the Tail-Shaft Bushing for Two Wheel-Drive models.

 

As I had said in a previous post...
The THM400/ 3L80E Lube-Circuit was a successful design that endured from 1964 through 1990, when the 4L80E was release for the 1991 model year.
Just like the THM400/ 3L80E Lube-Circuit; the EARLY-4L80E Lube-Circuit was also a successful design.

 

In the early to mid 1990s, there were plans for the 4L80E to be installed behind the new Duramax diesel engine.
While the EARLY-4L80E passed its original tests for durability/ longevity and maximum torque/ horse-power...
New more demanding tests for the 4L80E had started, in order to determine how it would perform behind the new Duramax diesel engine.

After some testing; there were concerns regarding the Simpson Planetary Gear-Sets possibly wearing-out prematurely due to increased thrust-loads, increased temperatures, and increased torque to handle.
It was decided by some of the GM/ Hydramatic Engineers (who I would call the "Yes-Men"), that the Lube-Circuit had to be changed for the 4L80E to be reliable behind the new Duramax.
The 1997 model year would start the use of the LATE-4L80E; along with a new Lube-Circuit and some Hard-Parts changes.

In two model years time after the LATE-4L80E went into production, the Simpson Planetary Gear-Sets would be changed/ updated in order to increase durability/ longevity.
While the new Lube-Circuit for the LATE-4L80E worked perfectly "On-Paper"... it did not work nearly as well in reality.
Some of the ideas behind the new Lube-Circuit were good... however most were unfortunately NOT.

The Lube-Circuit discussed further will ONLY be in regard to the LATE-4L80E until I state otherwise.
Below is an image of the LATE-4L80E Lube-Circuit (the Intermediate-Shaft is now SOLID with no passage inside):



To start off, the LATE-4L80E has the Lube-Circuit divided-up into 3 sections instead of 2 sections, like the EARLY-4L80E.
The first of 3 Lube-Circuit sections is just like the Early-4L80E, it lubricates the OverDrive and OverRun sections of the 4L80E transmission.
However the First section receives Lube-OIl from Regulated Converter Feed Oil inside the Pump, instead of cooled Lube-Oil from the Cooler-Return Fitting.
Other than this section of the Lube-Circuit, the remaining 2 sections of the LATE-4L80E Lube-Circuit are quite different.

Shown in the image below are the Cooler-Fittings... One of which has been moved rearward and placed into the Center-Support instead of being at the Pump:



Shown with colorful AN Fittings... one fitting is still at the Pump, but the other is located in the Center-Support.
Because this Cooler-Fitting is now entering the Center-Support...
The long Lube-Pipe that was used in the EARLY-4L80E is NOT used in the LATE-4L80E.
The LATE-4L80E does have a much smaller Lube-Pipe (can be seen in the Lube-Circuit diagram)... However it does not pass Lube-Oil in the same way that occurs in the EARLY-4L80E.
I will discuss this later in this Thread.

Here is an image of the Center-Support outside of the case... showing how the Cooler-Fitting enters the Center-Support:



One of the best aspects of the LATE-4L80E Lube-Circuit; is "The Idea" of the cooled Lube-Oil come directly from the ATF-Cooler and go directly into the Center-Support and to the Gear-Sets.
The reason that I say the idea of... is because putting the cooled Lube-Oil straight to the Gear-Sets is a very good thing...
However, the way in which the Lube-Oil actually passes from the Case-Fitting to the Gear-Sets is FAR FROM IDEAL.

This is because the LATE-4L80E does not have the HOLLOW Intermediate-Shaft PASSAGE to pass and distribute Lube-Oil.
The LATE-4L80E has a SOLID Intermediate-Shaft; and instead must force the Lube-Oil between the out-side of the Intermediate-Shaft and the inside of the Sun-Gear Shaft.
Lube-Oil passes through Oil-Grooves in the Sun-Gear Shaft; as well as squeezing through components and bearings.

Earlier I stated that the EARLY-4L80E and the THM400/ 3L80 use a HOLLOW Intermediate-Shaft for the Lube-Circuit to pass Lube-Oil to all the components.
Here are images of the HOLLOW Intermediate-Shaft:


Some of the lubrication holes in the Intermediate-Shaft can be seen in the image below:



Bushings are installed between the Intermediate-Shaft and the Sun-Gear Shaft.
These bushing do not use any Oil-Grooves, like in the image below:

 

I'm with CattleAC. I read a lot of the stuff you post but don't post enough in this forum. Mostly I post in Forced Induction or other stuff if I can contribute and try not to clutter up posts with fluff especially if I can't ask a meaningful question to stuff I don't know.

Thanks a lot for your contributions.

 

Shown in the image below is the LATE-4L80E Intermediate-Shaft:


This Intermediate-Shaft is SOLID, and has NO lubrication holes in it at all.
Here again is an image of the LATE-4L80E Lube-Circuit, with Lube-Oil shown in RED:


And here again is the EARLY-4L80E image:



Looking at the Middle to Rear of the Transmission in these images... a slight difference can be seen in regard to the Lube-Oil.
The image of the LATE Transmission shows Lube-Oil passing around the OUTSIDE of the Intermediate-Shaft.
The image of the EARLY Transmission shows Lube-Oil passing through the INSIDE of the Intermediate-Shaft.
The EARLY HOLLOW Intermediate-Shaft makes for a much better Lube-Circuit design, as it provides better lubrication to the transmission components.
The LATE SOLID Intermediate-Shaft makes for a restricted Lube-Circuit in comparison to the EARLY-4L80E.

Here is an image of the LATE-4L80E Sun-Gear Shaft Bushings with Oil-Grooves to allow Lube-Oil to pass through the Transmission:


Without the use of these bushings that have Oil-Grooves...
Lube-Oil would be even more restricted than it all ready is in this section of the Transmission.

The LATE-4L80E design Lube-Circuit provides Lube-Oil from the Center-Support outward in both directions.
Lube-Oil passes forwards, and stops after providing Lube-Oil to the Forward-Clutch...
and Lube-Oil passes rearwards, and stops after providing Lube-Oil to the Bushing inside of the Output-Shaft,
Shown again, below:


Lube-Oil stops here and does not Lubricate the Case-Bushing, like the EARLY-4L80E does.
This is because the LATE-4L80E Output-Shaft does NOT have the 2 lube holes that the EARLY-4L80E does.
EARLY-4L80E Output-Shaft shown again below:


The LATE Case-Bushing NOT being Lubricated in the same manor that the EARLY Case-Bushing is...
is the reason that the LATE-4L80E Lube-Circuit is divided into 3 sections, instead of 2 sections like the EARLY-4L80E.

Earlier on, I mentioned a smaller Lube-Pipe that is used in the LATE-4L80E.
The purpose of this smaller Lube-Pipe is to pass Lube-OIl to the Case-Bushing, and in Two Wheel-Drive vehicles, the Tail-Shaft Bushing as well.
This 3rd and final section of the LATE Lube-Circuit simply uses the small Lube-Pipe to connect into the AFL (Actuator Feed Limit) Circuit...
and lubricate the Case-Bushing and Tail-Shaft Bushing.

Using the AFL-Circuit to do anything other than its actual purpose, is a bad idea... Making the 3rd section of the Lube-Circuit far from i deal.
The AFL-Circuit is responsible for taking in Line-Pressure and regulating it down to a pressure that the Valve-Body Solenoids require to operate properly (Maximum of 105 - 125 Psi).
Unfortunately the AFL Valve-Train commonly wears-out; resulting in lower pressures than required.
This causes issues with shifting and insufficient Boost/ Line-Pressure rise, due to the Solenoids not receiving the correct required pressure to operate properly.
Taking oil away from the AFL-Circuit to lubricate the Case-Bushing and Tail-Shaft Bushing, ONLY makes things WORSE.

 

AFL Also is responsible for action at the PCS and subsequently the boost valve.
Low AFL means low line rise

Now, as bushings wear out, the boost valve wears out, and the AFL wears out...pressure goes down and down and those things just compound each other making it worse!

 

Great write up. I've learned a ton. Thanks

Question- On an early output shaft, do you use a solid or oil grove bushing?

 

I always use a 4r70w pump bushing
It is a quality bushing, fits perfect, and is tall enough to center a th350 bearing for rollerizing the output shaft

 

I'm asking about the bushing inside the output shaft.