As above, and add a little tweak/mod for the cooler lines or buy the HD model replacements, like I did. Honestly, this conversion has been done so many times now that you can buy everything needed for a bolt-in. PCM of NC has an adapter harness that allows you to not even have to move any wires, but there are minor changes to the transmission section of the programming to accommodate for the different trans gear ratios--allows for proper shifting and mph indication. It would take me 30 mins or more to type the step-by-step process here but there are many "how to" threads, and I've not seen a single one that catches absolutely everything, but they do cover all of the big items. If you read as many as you can find, making your own "to do" list from each of them, you will have 99% and what is left out of those threads will be small and can be easily managed during the swap process. I find myself wanting to write it out now! For my 2001 2wd, LS6 engined Yukon...
Parts:
1. Transmission: 2003 or earlier 4l80e and lower converter/flex plate cover. There were small changes in 2004, so if your is 2004 or later, easier to go with a 2004+ trans. If you get a 4L80 that needs rebuild, do not spend a fortune building a monster power unit...an oem 4L80 with a shift kit is already strong enough to handle what you plan to throw at it. So if you need a rebuild, just a basic "quality parts" rebuild with a shift kit is all that is needed. So you might be asking, if that's true why did you spend for a FLT level 5? Well, I repurpose things quite a bit, and I have a 700 hp 04 GTO 6-spd that I would like to convert to auto, and this transmission may find its way into that someday.
2. Converter: LS-style conversion torque converter. This allows you to bolt directly to your existing flex plate without 6.0L spacer and flex plate swap. Unless you get those items (in serviceable condition) for free, you will spend more money to get them than you will spend on the compatible converter from any of the reputable converter builders (I went with Precision Industries, but there are many very good ones). Also, you don't "need" a triple disc converter, but they are better at holding power...a "good" single disc will cover your need. You can buy an "off the self" converter from B&M/ATI/Hughes, etc and it will work fine. BUT, the custom builders are excellent resources to give you exactly what will work best for you. I found PI to be extremely helpful on the phone...a call to Yank, PI, Circle D, etc will be educational and worth your time. Note: I would spend for the billet cover construction...longevity of your investment will pay for itself.
3. Cross member: The 2wd version of the 4L80e is 1-11/16" longer than the 4L60e, and the rear trans mount is located further rearward on the 4L80. I've seen guys modify their existing cross member by cutting the center section and welding plate steel to each side to provide proper setback (PATC also offers this "version" but a bit expensive for me). Others have welded a piece of angle iron to the rear side and drilled a hole for the mount stud...this works fine as well. I personally bought a custom cross member from a PT.net forum member (dirt track racer) who has made MANY for guys there. You can even get it with a driveshaft safety loop, it desired. It does arrive raw so you have to either paint it or powder coat to prevent the mild steel from rusting.
4. Trans cooler lines: Depending on the year, there is a difference in the type of fitting used to connect the lines to the 4L80e case...my earlier model has the same press-in and secure with clips type of connection. I understand that the later cases have screw-in connection fittings. As mentioned above, you can do as I did and buy the oem GM set (or equivalent from other suppliers) for a 1500HD, or use your existing set with an adapter kit.
5. Trans yoke. The output shaft on the 4L80 has a 32-spline count, different than the 4L60, so you will need a new transmission yoke. Also, the "standard" TH400/4L80 yokes use a 1350 series u-joint--MY Yukon/4L60 uses a yoke that requires a 3R u-joint...fortunately, you can buy a 3R to 1350 adapter u-joint. Obviously, check your existing u-joint before you do anything...
6. Driveshaft. As the 2WD 4L80 is 1-11/16" longer than the 4L60, your existing driveshaft may or may not work. More likely it won't and you will need to either have your existing DS shortened or buy a new one. The decision to modify or replace depends on what you plan to do with your truck. The existing driveshaft has a "terminal speed" limit, meaning that there is a limit to the rotational speed that you want to turn it...I have heard tell of them coming apart at as little as 120 mph. I do not know the particulars of this anecdotal evidence (previous damage, wear, balance, etc) but with my intended use and frequency, I am not willing to risk it so I replaced mine with a steel "race" DS from Drive Shaft Specialists in San Antonio, TX...great quality and guaranteed performance. If you do decide to have your existing shortened, it would be a good time to also have it modified to fit a 1350 u-joint at the trans yoke end.
7. Electrical. There are a several ways to accomplish the wiring changes necessary to control the 4L80. This
THREAD provides the best "do it yourself" info I have come across. But I didn't want to do any manual changes to the wiring or a segment swap to the programming, so I bought a conversion harness at PCM of NC. To my thinking it is the easiest--obviously not the cheapest--way to manage the swap. With the harness I only have to make the following parameter changes: A. Max Out Trans Component Diagnostic Enable Temp (under Trans Diag) B. Set P0717 to no error reporting (4l70e to 4l80e applications only) C. Some vehicles require P0741 to be set as No Error Reporting. D. Must tune 4L80e shift points (different gearing) *see below* E. Changing gear ratios to match 4l80e is optional. It is only used for the ECM to calculate transmission slip. Since I have HPTuners but am no tuner...this is something I felt confident in doing.
The following is from an article I found in one of the online performance magazine sites...I believe Nelson Performance did the actual work in the article. This and my reading on the forums (and $$$) is all I needed to get the job done.
How to: 4L60E to 4L80e transmission swap
In this article, a fully built 4L80e from Finish Line Transmissions will be installed in place of the 4L60e. This 4L80e has been proven in 1000HP+ vehicles. This article is specifically written for the 2wd GM truck owner with a 4L60e transmission. However, the majority of these steps will apply to the 4wd and AWD trucks, or at least give you a good understanding on what is involved.
This article is for all you LSX based performance truck enthusiasts.
Are you tired of going through those weak 4L60e transmissions? Read more about it below!
- Before starting the teardown, disconnect the battery.
- It helps to have a lift to assist; however, all you do-it-yourselfers will find it just as easy on jack stands. Use caution when lifting your vehicle!
- Removing the transmission can be a mess. Since this transmission pan doesn’t have a drain plug, remove the pan to empty the transmission of the fluid.
Here’s what the fluid contained. As you can see there is a lot of material in the pan. The transmission obviously chewed some clutches up and from the way it sounds, broke some internal parts.
- After all the fluid is removed, reinstall the pan and move to the driveshaft. Using the correct wrench, remove the driveshaft bolts then gently pry the caps from the yoke with a large screwdriver.
- Next, disconnect every electrical component on the transmission. For this application, we disconnected the gear selector switch, vss connector and main transmission harness and gear selector.
- Now it’s time to remove the crossmember and exhaust y-pipe. Using a transmission jack, carefully lift up the transmission until all the pressure is off the crossmember. Then, remove the transmission mount bolt. Once done, remove the four crossmember bolts. Remember to have a buddy hold up the crossmember when the last bolt is removed so it doesn’t fall.
Carefully let the transmission jack down and let the engine oil pan rest on the front crossmember. It’s now time to remove the y-pipe.
- Remove the four oxygen sensors from the y-pipe. Simply disconnect them from the main harness or tie them up out of the way. Spray the exhaust bolts with lubricant to allow the nuts to spin off easily. If you break or strip one of these nuts, whip out the air hammer or grinder. Depending on how many miles and rust has collected on the studs and nuts will determine how easily they come off. After the nuts have soaked a few minutes, it’s time to remove the y-pipe. Having the crossmember out of the way makes is a lot easier. The 2 15mm nuts will also have to be removed in order to drop the y-pipe.
- Remove the 2 13mm bolts in order to drop the starter. After that, it’s time to remove the two splash guards held on by 10mm bolts. Now you can access torque converter bolts. GM calls the circular, removable plate on the bottom of the transmission bell housing a torque converter bolt access point. I have no idea why since it’s impossible to access the bolts through this hole.
Some converter bolts are hex head and others have a typical bolt. Try to be careful when removing these bolts or they will strip and then it will back to the grinder and Dremel to grind the head off.
To access each bolt, use the converter access hole to turn the flex plate with a screwdriver.
- Now it’s time to remove the bell housing bolts. The easiest way to remove the top, center bolt in the housing is to allow the engine and transmission hang like currently are. Grab a 4 feet extension and impact. Using a 15mm swivel socket, remove the bolt.
Now, using the transmission jack again, raise the transmission to an acceptable height and use the safety chain to secure the transmission to the jack. Remove the remaining bolts. There will be smaller 13mm nuts securing the dipstick and other lines.
Now that all the bolts are remove and the converter bolts are out, let’s pull this thing!
- Before we remove the transmission we have to disconnect the fluid lines. Using a small pick, simply remove the retaining clip. After that, the line will pull free. Keep a shop rag handy, it’ll make a mess.
Removing the transmission can be tricky. Lift the transmission to the factory angle. Place a wedge between the oil pan and crossmember. This will allow the engine to remain in its factory angle and the bell housing will break away from the engine a little easier.
You may have to aggressively shake the transmission back and forth in order to free the transmission.
A small pry bar will also aid in breaking the dowel pins that align the transmission and engine.
If your truck has about 50K miles on it like this one does, it may take some shaking and prying to free the transmission, but it will break free, just be careful.
As you lower the transmission, be sure all lines and wires are free. Pulling an electrical connector from its device or bending a line will cause issues.
- We chose a Yank torque converter from
www.converter.cc for this application. The larger makers of converters can usually adapt the front cover of the converter to meet your needs. In this case, we ordered a standard HD 4L80e 2800 stall converter.
This means, you must replace the factory 5.3L flex plate with a flex plate and spacer from any 2002+ ¾-ton HD GM truck that originally came with a 4L80e transmission.
The space allows the factory 4L80e flex plate to have the correct offset so that is lines up with the starter. Plus, the converter for this application has 6 converter bolts, so does the flex plate.
Since we have a spacer between the flex plate and engine, longer bolts will also have to be ordered.
Install the spacer on the back of the engine or tap it into the flex plate. Take notice that the spacer and flex plate have an alignment hole; be sure to align these holes. The rear of the crankshaft also has a matching hole, be sure to align all three when install the parts.
The flywheel is marked engine side.
Using red loctite, apply a small dab on each flex plate bolt.
Tighten the bolts in a star pattern to allow the plate and spacer to sit flush.
Once done, torque all bolts to 75lb/ft.
- It’s time to install your new HD 4L80e transmission. We chose the best performance transmission builder for our LS based Avalanche,
Finish Line Transmission. FLT’s transmissions will hold up to any punishment you can throw at it. From stock 4.8/5.3L engines to high performance LSX engines.
- Installing your new converter. This must be done correctly or you can damage the transmission and converter. Last thing you need now is to prolong the installation by destroying your expensive parts.
The easiest way to install a converter on the 4L80e transmission input shaft is to sit the transmission on the tail shaft. If you received your transmission from FLT, this is going to make a mess because FLT tests every transmission on their transmission dyno, which means the transmission still has fluid in it. So, it’s best to sit the transmission upright on a drain pan.
Before stabbing the converter on the transmission shaft, pour about ½ quart of transmission fluid in it and let it soak in. This will ensure the converter isn’t dry during start up.
Next, carefully sit the converter over the input shaft. This step is very important; the converter must seat correctly into the shaft and pump. If you’ve installed a converter before, you know the feeling when the converter is seated correctly. If this is your first time, spin the converter and it will fall down one step, continue spinning it until it seats again. The converter must seat/fall twice.
Performance converters can be tricky to install. The snout that protrudes from the converter is cut straight and the factory snout is chamfered. On our converter, we had to grind/file the two flat spots on the side of the snout so that the snout would slide into the pump easier.
Notice it wasn’t recommended on how to lift your 4L80e upright, this is completely up to you, just be very careful. This transmission is very heavy and may fall or slip out from under you. Get a buddy to hold the transmission while the converter is installed.
This is the amount of offset the converter will have when compared to the front of the bell housing. It’s about 1.5 inches.
- Before installing the transmission, it's a good idea to clean the transmission lines, cooler and any external coolers with a can of transmission line cleaner. You can do this by spraying into one transmission line and holding a bucket under the other. You can ensure they are clean enough when the fluid comes out clear. To finish the cleaning process, blow some air through the lines. This is very important if you're swapping transmissions due to breakage or clutch failure.
- Two dowel pins align the transmission and engine. These pins will sometimes get stuck in the engine. Be sure they are installed in the new transmission.
- Now that the converter is seated correctly, lift the transmission on the jack and secure with a safety chain. It’s now time to stab the transmission.
Before lifting the transmission into position, we’ve found it easier to set the dipstick tube up into the firewall. Let it hang into position while you lift the transmission. Once the transmission is lifted high enough, install the tube into the transmission grommet. Speaking of dipstick tube, you will need a dipstick tube from a 2002+ HD truck.
The 4L60e dipstick will be reused.
Carefully lift the jack up while paying attention to all the wires and transmission lines until the two dowel pins are align with the transmission holes.
Wiggle the transmission forward and immediately get four transmission bolts started.
At this time, ensure the converter will spin freely. If it does not, the converter is not seated correctly. You must remove the transmission and try again to seat the converter in the shaft and pump.
Do not proceed if the converter does not spin. Tightening the bell housing bolts will crush the pump and possibly damage the converter.
If the converter is seated correctly, the converter will be about 1/16th inch from the flywheel.
If the converter does spin freely, snug the bolts down while making sure everything is lignin up correctly. Now you can tighten the bolts up.
Lower the transmission jack just enough to access the top, center bolt. Install the bolt.
Reinstall the fuel line bracket and vent tube bracket that are held in place by the bell housing bolts.
- At this point, decide if you want to install the torque converter bolts. They can be done at a later time. Make sure a small amount of red Loctite is used on the bolts.
We used aftermarket converter bolts that were stronger than stock bolts; however, stock converter bolts can be used.
- The 4L80e has a lower, removable bell housing cover. This part can be purchased for the same truck as all the other parts.
Install this lower piece and the starter if you’ve already installed the converter bolts.
- Reinstall the y-pipe and all O2 sensors.
- In order for the transmission to shift correctly, a conversion harness must be purchased. This harness re-pins the 4L60e configuration to the 4L80e pin configuration. The harness simply plugs into the main harness and installs into the factory transmission connector.
- The 4L80e transmission is longer than the 4L60e transmission so a conversion crossmember is needed.
- The factory transmission lines are not going to line up. The front line can be straightened out so that is pushes in to the front transmission line connector.
The back line needs to be extended. There are several ways of doing this; this is how we did it:
- Now it’s time to reinstall the driveshaft. For this particular application, it was decided that the factory driveshaft would not be reused. The factory drive shafts for the Avalanche are made of extremely thin aluminum. Cutting and welding on the factory driveshaft wasn’t an option for us.
Luckily, the Avalanche has the same chassis as a Suburban. The Suburban was available in ½ ton and ¾ ton. All ¾-ton HD trucks had the option of having a 4L80e transmission. This means we we’re able to use a factory Suburban HD driveshaft.
We also got lucky because this particular driveshaft is a monster; it measures 5” in diameter.
Anyone who has destroyed a driveshaft at high speeds knows this isn’t fun at all. The larger diameter will help increase the critical speed of the shaft and allow it to turn higher RPM’s.
- Finally, recheck all you work and install anything we forgot to mention in this article.
Before the truck is operational, you must have your PCM programmed with a 4L80e calibration.
Fill the transmission with about 8 qts of Dexron VI fluid. Start the engine and ensure each gear engages. This also allows the valve body to open all its orifices and valves.
Recheck the fluid and let the transmission reach operation temp. Recheck the fluid one more time.
With the addition of the higher stall converter, a larger transmission cooler is required. We went with the largest B&M cooler we could find. Temperatures are under control during any type of driving. They average about 140 degs on the highway with 70 deg weather.
