Big Bertha
Newbie
Let me start by saying this isn't my first transmission removal, or even my 2nd or 3rd. But that being said there are almost always vehicle specific obstacles and difficulties, and there is usually an ideal order to do things in. I'm posting this in the hopes that it will help someone else as I had a hard time finding useful info on an R&R for the 4L80E in my 97 6.5TD K1500 Suburban.
Before you even start, I strongly suggest that you get an actual transmission jack, and 6 ton jackstands, even if you are under 3 tons, as the 3 ton jackstands don't really give you enough height. You want to get the frame a good 2 feet or so off the ground so you have room to get the trans out from under it, not to mention it makes it easier to work on. I have some "S" wrenches, and offset wrenches that I also found to be helpful reaching some of the harder to get to fasteners. An impact wrench can also be helpful in speeding things up, I also found myself lamenting that I do not have ratcheting wrenches, and couldn't find my 15mm socket for my spline drive open socket ratchet(similar to a ratchet wrench).
Tools:
11mm wrench
Ratchet/s, an impact gun is also helpful if you have one but not needed
13mm socket/s
15mm socket/s & wrenches
18mm socket/s & wrenches
Breaker bar
Prybars
Transmission jack
Floor jack
6 ton jack stands
Flathead screwdriver/s or picks for the electrical connectors
Before starting you should probably drain the transmission and tcase, or you can be like me and roll around in transmission fluid all day instead because you were lazy. If your transmission pan doesn't have a drain plug, loosen or remove the bolts at one of the corners of the pan, but don't take the whole pan off, this will let it drain out in a controlled manner like pouring from a pitcher you will have to break the seal on the gasket to get it to drain. You may need to wait till the crossmember and transmission mount are off to lower the transmission so that it will drain at one of the rear corners.
Driveshaft:
First up, remove the rear driveshaft, you should mark the orientation of the U-joints to the yokes so that they go back in the same way(to prevent driveline vibrations) they are held in by 2 straps and 4 bolts each, the bolts are 11mm, or I believe a 7/16 can also be used, it is easier to do with the truck in neutral so you can rotate the driveshaft for easier access, you can use a larger flathead or small prybar to keep it from rotating as you loosen, or put it back into park. Then you will want to use a screwdriver or prybar to pop the U joints out of the yokes.
Crossmember:
Don't bother trying to disconnect other stuff with it in place, it makes it harder to get to things. you'll want to put your transmission jack under your transmission, and set it to just start taking the weight of it. Once the transmission is supported by the jack, then you can unbolt the transmission mount from the crossmember, it will be held to the crossmember by 2 15mm nuts. After that unbolt the crossmember, it is held on by 4 18mm bolts and nuts. Then use the transmission jack to lift the transmission until the studs in the mount are lifted out of the crossmember. Now you can remove the crossmember, I'll admit I had a harder time getting it out than I should have, the trick was passenger side all the way back to the torsion bar xmember, and driver side came out all the way at the front.
Transfer Case:
Once the crossmember is out, you have easier access to things, and actually be able to see where things are, start with the front driveshaft, it's the same as the rear, but you'll want to disconnect both ends to get it past the exhaust crossover pipe. Then you'll want to unplug all the things connected to the transfer case, I believe there were 3 or 4 electrical connectors, most are pretty straightforward, but the tcase connector if I recall had a retainer on it, you have to push the retainer through before you can unplug the connector. There is also a vent tube connected to a hose that has to be disconnected. With all of that stuff disconnected you are ready to pull the transfer case, it is a PITA getting to the bolts holding it in, or at least without a lift. There appears to be a mounting plate between it and the transmission, I believe you can remove the bolts from either side to disconnect it. I started by trying to get the bolts going into the transmission, but was having a hard time getting to the ones up top so then I undid the bolts going into the transfer case side instead, there are 6 of them, and they are 15mm you will likely want to lower the transmission jack to get to them easier. With that done you can pull the tcase out, be prepared as it is quite heavy, I would guess it to be around 75 lbs, with the bolts undone lowering and or raising the transmission jack may break it free from the mounting plate, it did on mine, otherwise you might find them stuck together and have to pry it off. You will also likely find the tcase will rotate to it's heavy end hanging down, you will want to set the tail end of the tcase onto the torsion bar xmember, from there you can rotate it 90* sideways and out, you might have trouble getting it away from the transmission, I did so I raised the transmission back up to get it's tail away from the tcase yoke.
This is as far as I got today, more to follow when I finish it, probably tomorrow.
Before you even start, I strongly suggest that you get an actual transmission jack, and 6 ton jackstands, even if you are under 3 tons, as the 3 ton jackstands don't really give you enough height. You want to get the frame a good 2 feet or so off the ground so you have room to get the trans out from under it, not to mention it makes it easier to work on. I have some "S" wrenches, and offset wrenches that I also found to be helpful reaching some of the harder to get to fasteners. An impact wrench can also be helpful in speeding things up, I also found myself lamenting that I do not have ratcheting wrenches, and couldn't find my 15mm socket for my spline drive open socket ratchet(similar to a ratchet wrench).
Tools:
11mm wrench
Ratchet/s, an impact gun is also helpful if you have one but not needed
13mm socket/s
15mm socket/s & wrenches
18mm socket/s & wrenches
Breaker bar
Prybars
Transmission jack
Floor jack
6 ton jack stands
Flathead screwdriver/s or picks for the electrical connectors
Before starting you should probably drain the transmission and tcase, or you can be like me and roll around in transmission fluid all day instead because you were lazy. If your transmission pan doesn't have a drain plug, loosen or remove the bolts at one of the corners of the pan, but don't take the whole pan off, this will let it drain out in a controlled manner like pouring from a pitcher you will have to break the seal on the gasket to get it to drain. You may need to wait till the crossmember and transmission mount are off to lower the transmission so that it will drain at one of the rear corners.
Driveshaft:
First up, remove the rear driveshaft, you should mark the orientation of the U-joints to the yokes so that they go back in the same way(to prevent driveline vibrations) they are held in by 2 straps and 4 bolts each, the bolts are 11mm, or I believe a 7/16 can also be used, it is easier to do with the truck in neutral so you can rotate the driveshaft for easier access, you can use a larger flathead or small prybar to keep it from rotating as you loosen, or put it back into park. Then you will want to use a screwdriver or prybar to pop the U joints out of the yokes.
Crossmember:
Don't bother trying to disconnect other stuff with it in place, it makes it harder to get to things. you'll want to put your transmission jack under your transmission, and set it to just start taking the weight of it. Once the transmission is supported by the jack, then you can unbolt the transmission mount from the crossmember, it will be held to the crossmember by 2 15mm nuts. After that unbolt the crossmember, it is held on by 4 18mm bolts and nuts. Then use the transmission jack to lift the transmission until the studs in the mount are lifted out of the crossmember. Now you can remove the crossmember, I'll admit I had a harder time getting it out than I should have, the trick was passenger side all the way back to the torsion bar xmember, and driver side came out all the way at the front.
Transfer Case:
Once the crossmember is out, you have easier access to things, and actually be able to see where things are, start with the front driveshaft, it's the same as the rear, but you'll want to disconnect both ends to get it past the exhaust crossover pipe. Then you'll want to unplug all the things connected to the transfer case, I believe there were 3 or 4 electrical connectors, most are pretty straightforward, but the tcase connector if I recall had a retainer on it, you have to push the retainer through before you can unplug the connector. There is also a vent tube connected to a hose that has to be disconnected. With all of that stuff disconnected you are ready to pull the transfer case, it is a PITA getting to the bolts holding it in, or at least without a lift. There appears to be a mounting plate between it and the transmission, I believe you can remove the bolts from either side to disconnect it. I started by trying to get the bolts going into the transmission, but was having a hard time getting to the ones up top so then I undid the bolts going into the transfer case side instead, there are 6 of them, and they are 15mm you will likely want to lower the transmission jack to get to them easier. With that done you can pull the tcase out, be prepared as it is quite heavy, I would guess it to be around 75 lbs, with the bolts undone lowering and or raising the transmission jack may break it free from the mounting plate, it did on mine, otherwise you might find them stuck together and have to pry it off. You will also likely find the tcase will rotate to it's heavy end hanging down, you will want to set the tail end of the tcase onto the torsion bar xmember, from there you can rotate it 90* sideways and out, you might have trouble getting it away from the transmission, I did so I raised the transmission back up to get it's tail away from the tcase yoke.
This is as far as I got today, more to follow when I finish it, probably tomorrow.
