Secrets of the Universe and 4L60 - 80E transmissions

I thought I would share some of the inner workings of the 4L60E and 4L85E transmissions, and some of the common problems I’ve seen with them over the years.
The 4l60E, was introduced in 1993, is an electronic version of the 700r4, which was introduced in 1982. The 4L65E is heavy-duty unit for use behind the 6.0L engines, and was introduced in 2001. Some of the parts were improved to increase its torque capacity. Input and reaction carriers were changed from 4 to 5 pinion gears. An extra clutch was added to the 3-4-clutch pack, hardened input shaft, heavy-duty low roller clutch with wider rollers, and a heavy-duty sun shell and sun gear. All of these parts can be used in the 4L60E. I think they should've just used the 4L65E in all applications instead of having two versions of the same transmission.
The 4L80E has been around since 91 and is basically a turbo 400 with overdrive and electronic controls. A lot of the parts have remained virtually unchanged since 64 when the 400 was introduced. When the 4L85E came about in 2002 and had a higher torque capacity. Parts that were improved were the input and reaction carriers, from 4 to 5 pinions gears and an improved overdrive planatary and drum. The 4L80E in my opinion is a very strong transmission. It’s had its share problems over the years but currently is the best it’s ever been. One common complaint I see a lot is “no reverse”. In the 91-96 units I see a lot of direct/rev pistons broken in two. These are made of aluminum. In 97 they went to a metal piston with a bonded rubber seal. I have yet to see one of these fail yet and I use this type when I rebuild them. The reason the piston breaks is due to a high line pressure in reverse. The reverse boost valve wears out and causes a uncontrollable line pressure. I’ve heard of cases where the line pressure has exceeded 600 psi, and when this happens you can get some serious parts breakage. I’ve heard of cases splitting in two and have seen myself a direct drum, which is made from cast iron, split apart. Every time I see a unit with a reverse problem it always has a worn out boost valve. The latest 4L80E units I have worked on was a 2000 model with no reverse. I was a little surprised to see this complaint on a newer model transmission because I knew it had a steel piston with a bonded rubber seal, which usually does not break. I took the unit apart and everything looked perfect inside except for the reverse band which was burnt, usually that is not a problem with that model. Anyway the cause of the problem again was the boost valve. So if there is one thing that I would like to see improved with the 4l80E is if they would improve the reverse boost valve. Is there any drawbacks with the 4l80E? Not really, except maybe with the weight of the unit. The torque converters on these things weight nearly 70lbs! I think that there is quite a bit a horsepower that is being thrown away - with such a heavy unit.
As for the 4L60E, not too many changes has been made to the major components of the transmission (planets, drums, gears, etc.) since 82. A larger input sprag and low roller clutch is about all that’s been changed and that was back in 86-87. Once again “no reverse” is fairly common complaint with these, but for a different reason. I see a ton of broken sun shells. There is a splined area of the shell (splines on to reaction sun gear) that breaks clean off. This area is just not strong enough. So GM has come out with a redesigned shell in the past couple of years to help with this problem, it’s a bit thicker and has more of a radius where the splines meet the base of the shell. Well now guess what? Instead of breaking the splines , they are now striping out! I’ve seen this problem many times on the 2000 and newer units, and have heard this from other builders too. I am a little reluctant to get new shell from the dealer because of this current problem. I’ve heard from other builders that new shells they bought and put in have been striping out in as little as 20,000 miles! I think that the sun shell is the weakest part of the 4L60E. I have tried to use an aftermarket shell that has hardened splines whenever possible.
There are a few other common problems I see. One problem is that there is a check ball that likes to wear out the separator plate, it eventually blows down through it, but it doesn’t occure all the time. It might depend on how hard it is driven. In the mid 90’s, I saw quite a few bearings in the planetaries fail. Usually it would cause a lot of damage, but I think that it was due to a bad batch bearings.
In the quest for better gas mileage GM has changed the lock up strategy of the torque converter over the years. The original 700 and 93-94 4L60E used a on/off type lockup. Meaning it was totally off or fully on and locked.
In 95 they went to a PWM (pulse width modulated) lockup, which controls the aggressiveness of the apply and release of the torque converter clutch and it allows a little bit more slippage for a smoother feel.
In 1998 GM went to a different strategy called “Ec3”or electronically controlled capacity clutch.
This strategy has made a big difference in fuel economy by starting the apply of the TCC at a much lower speed and continually slipping it until it reaches highway speeds. It begins to apply in 2nd gear and slips up to 250 rpms depending on speed and engine output. In order for this strategy to work a new converter clutch lining had to be developed to withstand the slippage and heat generated. What GM came up with is a woven carbon fiber material that is very porous that allows fluid to flow though it for better heat transfer. This stuff is practically indestructible. One of the problems shops face is getting a replacement converter when doing a rebuild. GM holds a patent on this material. The aftermarket converter companies have been trying to find a suitable replacement material that will hold up. Several companies are very close to releasing their own material. Until then we have only two choices, get a rebuilt converter with a good “used” woven clutch or buy the converter from the local GM dealer. I personally prefer to go new. I just don’t trust a used lining although this stuff is extremely durable.
The 4l80E uses the PWM type strategy and uses a Graphite/ Kevlar composition lining for the TCC.
The 4l60E PWM units use this material also.
Both the units have been using a High Energy Graphitic lining on the clutch plates and bands for several years now. This material is very durable and can withstand high temperatures. It’s not uncommon to take apart a high mileage unit and find that the clutches still look as good as they day they were put in new.

One of the areas that I would like to explore further and have some questions about is that of the adaptive learning strategy with both of these transmissions. The adaptive strategy has been in use since 93, but in a basic form compared to what it is today. What is does is that it makes adjustments in line pressure to obtain consistent shifts and helps to increases the life of the transmission. As clutch material wears away, the clutch pack clearances increase, the timing of apply can change resulting in shift overlap. Shift overlap is the time it takes to complete a shift. There are several types of Adaptive learning in use and depends on application what strategies are used. The most common types are, Shift adapts, steady state adapts, and garage shift adapts. Shift adapts are what measure the overlap time between shifts. First the computer must recognize an up shift as adaptable. There are some conditions that can cause an incorrect line pressure adjustment such as the a/c compressor cycling during a shift or a radical change in throttle position, and these types of shifts won’t adapt. When a shift is started a number of things are checked such as throttle position, transmission temp, vehicle speed, and engine rpm, in that order, if the actual shift time is valid to compare to the calibrated desired shift time. If these items are met during the entire shift the shift is considered adaptable. Once the shift is adaptable the computer compares the actual shift time and the desired shift time and calculates the time between them. This time between the two now becomes shift error. Actual shift time is the time from when the computer commands the shift to the time the engine rpm begins to drop from the commanded shift.
If the actual shift time is longer than desired shift time (slow engagement, soft feel) the computer will adjust the current to the pressure control solenoid to increase the line pressure for the same up shift the next time it has to do it - under identical conditions. If the actual time is shorter than desired shift time (quick hard shift) the computer will decrease the line pressure for the same shift under identical conditions.
Steady state adapts is a strategy that allows the computer to make adjustments to line pressure if a clutch or band slippage is present. The computer monitors vehicle speed and engine rpm to determine if slippage is present, if there is, the current to the pressure control solenoid will be driven down until the slippage stops or sets a code for max adapt. The computer will constantly adjust the current and determine if the slip is still present. If slippage is gone, the computer will raise the amperage to the PCS.
Garage shift adapters are for controlling the feel when shifting into forward or reverse from park. Shift times are taken from the time it takes for the engine rpm to drop from the time the range switch which indicates movement from the park position. When the brake is applied the line pressure is increased and the time it taken will determine how long it should remain boosted for the proper engagement.
One of the questions I have is, how will installing a shift-enhancing product affect the shift adaptive strategy of today’s transmissions. If a shift is shortened isn’t the computer going to try and compensate by reducing line pressure? Reducing line pressure during a shift in a performance type application is not a good idea in my opinion. (Just a side note: I’m going to refrain from using the term “shift kit ™” because it shouldn’t be used as a generic term. It is a reregistered trademark of Transgo along with “reprogramming kit™” and they don’t like it if it is used to describe someone else’s product.) Is there a way around this Problem? Transgo does make a product that replaces the pressure control solenoid with a vacuum modulator like we used on the TH 350’s and 400’s, to control the line pressure. By using vacuum to measure engine load, the computer wouldn't be able to make adjustments to the PCS, hence a more stable line pressure during shifts. I don’t know if it can be disabled thought the computer by reprogramming it or not. Maybe there are some hardcore computer power tuners out there that knows a way around it.
I think that some of the shift complaints that some people have posted on different boards might just be that the transmission hasn’t fully adapted yet. When I first bought my Avalanche, it was the first vehicle I’ve owned with the 4L60E.
Although I build these transmissions all the time for other people, I still questioned some of the shifts for the first few months. I had an occasional harsh 1-2 shift and a clunking 2-3 shift, both have since disappeared and it now shifts smooth as butter. I think that it takes time for the adaptive learning to fully work because not all shifts are adaptable. But if you have a 1-2 shift that is hard all the time, that could be a different story. The first thing is to have it scanned for codes. Some trouble codes will default the transmission to high line pressure, which will give harsh shifts.
One code that has been a big problem with the 4L60E is the code 1870 trans component slipping. In 1995 the lockup torque converter went to a PWM type control (pulse width modulated) from the on/off type used on the 700’s and 93/94 4L60E. Two of the valves used, caused the TCC regulator and isolator valves to wear out the valve body bore because they are constantly moving. This causes excessive converter slippage and sets the code. GM has been working on this problem for several years. I know that when a customer of mine with this problem took their vehicle to the dealer, they put in a remanufactured service replacement valve body in it. These valve bodies had the bore reamed out and a larger valve put in. The only problem is that these larger valves still wear the bore out. In 2000 GM made a change to the separator plate and gaskets to help with this problem. I attended a transmission seminar last year on the 4l60E transmission and was told that GM has issued their final fix for the problem for the 2002 model year vehicles. I guess only time will tell if it is fixed or not. What I do on all 95 and up units is replace the valve assembly with an aftermarket one that has been designed to eliminate 1870. It’s made by a company that produces high quality transmission products that fix the common problems with various transmissions. It works very well and won’t cause any further wear to the valve body.

I didn't write this article, I just received it in a email from a technician friend of mine and figured that I would relay this information to you.
You can make your own decisions as to what upgrades you wish to do to your transmission or what you feel will improve the performance of these models of transmission.

Just taking out a $L60- 65E and replacing it with a 4L80 -85E is not the solution due to the fact that the transmission shops see 4 times as many problems with the 4L80E as they do with the 4L60E.

Now I know of someone else besides me with absolutely nothing fun to do on a Saturday night! Interesting post nonetheless.

Good Info, Thanks for sharing.

I installed a new Shift kit By Ratio Tek, Owner is Steve Younger, Who is the guy behind TransGo's shift kit, Steve started his own company and knows his stuff with these transmissions.

He redesigned His shift kit to work better than the previous TransGo kits.

He has added a " clip" in his kit that installs in the valve body to prevent 1870 codes. One of many refinements.

It is working good. You can actually feel converter lock up , instead of slipping its way to applying.

The Ratio Tek kit is a great addition to help a stock trans live longer.

The Key is that with the right power tuner, you do not need to install anything into the transmission other then the better then stock parts.

There is no advantage to trying to upgrade your 4L60E to a 4L80E

It actually robs horsepower and does nothing for the performance.

Hey guys newbie here and this post has alot of excellent info. I'm having an issue with my 4L60E trans in my 2006 Denali XL with a 6.0L V8. It wont,go into reverse, and will not drop into 1st gear at a stop. One shop won't bother to open it up just said I need a new trans. Second shop pulled a solenoid code failure. So he the dropped pan, replaced all 5 solenoids, changed fluid and filter and that didn't fix the problem. Any ideas what it might be and a fix? Other than dropping 2 grand for a new trans? Denali is my primary work vehicle and it's been down for 2 months. I'm dying to get it back on the road especially because I'm stuck driving an open top jeep in the dead of winter in a ski resort town!