Transmission Teardown How Automatic Car Truck Transmissions Work

In this video, we're gonna rip a transmission apart and show you what's wrong with it. Now, before you do this, you wanna check some things out. You wanna make sure that vehicle shifts in all the gears, road test the vehicle, not only cold, but hot, go up on the highway, see what's missing. If there's a certain gear that's not shifting properly, whether it's a lag or a harsh shift, check those things out, write them down, and that'll help you with diagnosing the internals of the transmission.

One other thing to think of before you take this all apart is transmission shift adapts. Now, newer vehicles have adapts so that when there's internally worn components in the transmission, the computer's gonna adapt to those. Now, if you disconnected the battery recently or someone programmed something on the vehicle, it may shift a little weird. There might not be anything wrong, and you just have to drive the vehicle. The normal way to do this is you would support the engine and transmission from up top and use some kind of a bracketry, something similar to this. The problem is this one doesn't fit. It's too short. It needs to go all the way to the fenders on both sides. So this isn't gonna work for me. I'm gonna have to do this a different way.

Now, before I disconnect the battery, I want to lock the steering wheel, make sure the wheels are going straight ahead, and take the seat belt, and just go through here. And you can actually buckle it. You can move the seat forward. Now, that'll prevent the steering wheel from spinning. Now, the battery is located underneath here in the back seat. Slide this cover off and just disconnect the negative terminal. Now, what I need to start doing is disconnecting everything from above the motor. This fuse box has to come out. There's a panel underneath there. The bracket has to come out. And then there's an engine mount that's gotta come out, anything also connected to the engine that's also gonna be connected to the body, the cover, the airbox, this panel right here. And that's what we're gonna do next.

So I got most of that stuff off. The airbox is still sitting in here. I'm gonna take this computer out of the way. I need to disconnect these wires anyway if the wires are gonna be attached to the motor right there and also the wire right here. And I will pull the reservoir off next. So that's what we'll do. I've got most of it disconnected, anything that's in front here that's gonna prevent the engine when I drop it from getting in the way. I'm leaving the AC line, so I don't have to touch that yet. The coolant hoses, I'm not ready to take those off yet because I don't want the coolant dripping everywhere. I'm still gonna take some other things off first. Now, I'm gonna have to remove some stuff over in this area. Now I'm gonna remove the vacuum hose that's on the brake booster and then these wires right here. Because the engine harness is harder to disconnect from the engine, I'm gonna have to disconnect the grounds here, here, and at the ABS module right there, and then wrap it over the engine.

So we still have the fuel lines connected, we still have the transmission cooler lines connected, we still have the heater hoses connected, and the engine coolant radiator hoses, the upper and lower hose. So I'm gonna leave those connected right now. Now I'm gonna take all the wheels off. I'm gonna drain the transmission fluid in the drain plug right here using an 11-millimeter socket. Make sure you have a drain bucket. Now, most of that's all drained out. So let's put the plug back in and snug it up. On each side, I'm gonna remove the tie rods from the knuckle and also remove the sway bar link from the strut. Now I wanna get this flap out of the way. Just take these push pins out and then the lower control arm. There's two bolts right here, two nuts on top, and then a bolt and a nut right there. Take those out. Now, with those bolts out, you can take a pry bar and pry this out a little bit. And before you pry it out too far, we're gonna separate that axle from the transfer case. You have to take the pry bar, get underneath there, and just pop it out. There we go. So that's loose. There we go. A little bit of fluid in there. And then just move this to the side. Just make sure there's no tension on the brake hose. I'll do the same with the other side.

I'm gonna take the driveshaft off. Once before I do that, I will just wanna mark it with a marker. I just wanna put it back to where it was when I took it apart. That way you don't have any unnecessary vibrations that you could potentially create. And I'm gonna do the same on the rear yoke as well. Now I'm gonna take this crossmember down and a couple bolts that hold it on, and then we'll pull the exhaust down. I gotta disconnect the O2 sensors, disconnect it way up there, connector on the backside, and then take the nuts off of the flange. And there's another flange there and right there. I'm gonna disconnect the steering rack. Just slide this boot up. And then there's an 11-millimeter bolt. Just take that bolt out, and then you can disconnect that lower shaft, slide it out of the way. All right. This is just sliding the intermediate shaft off the steering gear. All right. There we go. It's disconnected. Because we don't have an AC machine, we're gonna have to disconnect the AC compressor and just like wire tie it up against the body. So that stays with the body while we drop the powertrain. So I'm gonna have to take this belt off and use a belt tensioner tool. Slide the belt tool off. Now I'm gonna remove the bolts from the compressor. There's two bolts on the bottom, two bolts on the top, one bolt on the bottom, and one nut and a stud.

Now, before I drain the coolant and before I drop the vehicle down again, there's a couple of bolts that'll be easier just to take out now. I'm gonna take these two bolts out of this bracket. I'm gonna leave this bolt in that's holding the cradle to the body, same on this side and then same in the back. There's two in the back bracket. So just those ones and those ones. And then also underneath the engine just because it'll be easier to do now, there's these two bolts. I'm gonna take off the transfer case. There's still three bolts holding it up top and then this bellhousing bolts, those three, and that one as well. Take those off. There's a lower radiator hose right here. Now, I'm gonna disconnect that and drain the coolant. I'm gonna pull off this upper coolant hose, and then underneath that, there's an engine bracket. I have to pull that off. There's two bolts that hold that down. And then down here, I'm gonna pull off this AC bracket. This goes to the pressure line or one of the AC lines. All right. So now just take that AC compressor. Just push it back. Just push it. There is a little frame right here that I wanna...I'm gonna wire tie that to the fan later, but I can do that right this second. And this power-steering hose here that's gonna come out of there. So, that'll be good for now. Now, everything seems to be disconnected on the front of the motor. Now we're just gonna disconnect everything from the back. We're gonna take this evap line off. Then I'm gonna disconnect the fuel line. And then there's two transmission cooler lines that I need to disconnect. There's a couple nuts that hold those on and then some brackets. There's a 10-millimeter nut for this one that goes in the back and then also this. Once I get that stuff out of the way, I'm gonna fold this harness back onto the powertrain and be good to go.

Now I'm gonna support the cradle with some jack stands underneath. Right there is good. Now I'm gonna take those cradle bolts out. There's gonna be two in the rear and two in the front. Just stay clear.

Now I'm gonna raise the vehicle. Now I have to watch out for this control arm. Just make sure it doesn't get snagged on anything. You can spin it around. We have two. Same with the other side. This should be all right that way. And like the tie rod end and the sway bar link are gonna go down with the powertrain. And just go slow and just make sure you don't hear anything cracking. I'm gonna take the alternator off. I'm gonna leave it off because it gave us a lot of trouble when dropping this whole powertrain down. So, I'll take these. There's a nut here, and I'll take these studs out, disconnect the wire, take this bracket off, and take this pulley off. Take that off. Now I need to remove the catalytic converter to get the starter out so that I can access the torque converter bolts. I'm gonna take off the shield and the other bolts that are on there. I did put the oil filter back on just temporarily so that it doesn't drip all over the place, but I might have to take that off again. Now, I need to get to the torque converter bolts. So I need to turn the flywheel. How I'm gonna do that is actually use a 19-millimeter socket on the crankshaft pulley bolt, and as I turn the crankshaft, then I'll be able to line up the bolts right there. And I'll just take those out one at a time.

Now we're gonna remove the transfer case. Now, I could probably leave that attached and just disconnect the transmission and slide it away, and the transfer case would just stay there, but there's an O-ring that's on the transfer case that's actually pretty crucial, and it's not easy to get the transfer case back on to the transmission without ruining that seal. We're gonna replace it anyway, but it'll just make it easier. So what I need to do is support the engine over here because there's a motor mount that's right there that's actually attached to the transfer case. So, I could support it from underneath using a floor jack, but I'm actually just gonna use an engine hoist and support the engine. It'll be a little bit safer. Now I'm gonna remove the motor mount. I'm gonna take the nut off from underneath. And then there's three bolts that hold...that attach the transfer case and then four bolts that attach to the engine block itself. Take those all out. Now, these are the last three bolts that are holding the transfer case on. I'll have to take those out. I am gonna use a floor jack to help support the transfer case. All right.

So now that I have the transfer case out, I am gonna have to temporarily put the motor mount back in position just so I can support the engine over here. If I had two engine hoists, then I might not be able to...I might not have to do this, but we're gonna use the engine hoist to take the transmission off of the engine. So, let's support that, put this on. Now I only put a couple of the bolts in the actual engine mount bracket, and I'm not even gonna tighten the nuts down for the mount itself. You can just lower this down. That's good. I'll just take this chain off. Now I'm gonna take this wiring harness, move it out of the way, disconnect the connector at the transmission itself, remove that. Start removing some of the bolts. There's a couple bolts over here around the bellhousing. And then I'm gonna support the transmission, and we'll take that motor mount out.

All right. So I got those out. I got the chain all supported. I did have to move the floor jack over to support the transmission because the way when I was raising up the engine, it was raising the whole engine. So, I just had to move it over so it just tipped. So now we're good. Now, just support the transmission a little bit. Now just move the floor jack over underneath the engine again.

All right. So now all those bolts are out. Transmission's loose. Just take a pry bar, pry it out. Just be careful. Raise it up a little more. And be careful, you don't want the torque converter to fall out. So it's tipping a little at an angle I don't really like but just slide it out of the way. Now we're gonna start taking the transmission apart. Have a nice, clean table. What you would normally wanna do is have this in a stand so you can pivot and rotate it. We don't have that luxury. So we're gonna do it on the table. And if you had that stand, you could pivot this transmission so the torque converter is straight down, and there's specialty handles you can get that thread into there, and you can pull that straight up. I'm gonna do the best I can. I have a bolt. It's gonna thread into there. And then carefully take this out. Slide it. And there's a lot of fluid in this. What I'm gonna do is tip this upside down in a bucket and let the fluid drain out. Now we're gonna take this valve body cover off. There's a bunch of bolts. Come around it, and some of the fluid's gonna come out when we do this. There we go. There's more fluid...a lot of fluid. Now, this is the TCM or the transmission control module. This is basically the brain. This is what tells the transmission what to do, and also the solenoid pack. So the fluid goes through these solenoids, and the computer opens and closes those solenoids. Now, I'm gonna disconnect that, take these connectors off right here, and then take out all those bolts.

All right. This slides right off. You can look at the backside. And this is actually what caused this transmission to fail. These two diaphragms are actually broken. They should be solid like this one or this one. And that's what's giving us our drivability and our check engine light. Now, here is where the valve body is located. Right here, there's two pieces of metal sandwiched together, and that's where all the valves switch back and forth. So the solenoids command the valves to go back and forth. Not a lot of problems with the valve bodies in these vehicles. You don't really have to rebuild them that often. You can pull it off and check the valves to make sure everything moves properly, especially if you're having a problem with one of the gears hanging up or something, you're gonna wanna check that valve. Now here is where the park neutral safety switch is, the prindle or the range selector switch. So if you had to replace this, you're gonna have to take this cover off. You're gonna have to take this lever off here, and there's a little pin right there that holds that on. You have to take that nut off. Take the lever off. And then I actually made this specific tool just to get to this, and you have to pry that. It looks like a nail. You pry that out a little bit, and then you can slide it out and slide the new one in, and then you have to hammer it back in. So you definitely have to take that cover off first because you have to disconnect this, which is actually connected to here. That's the input speed sensor. So you can't take this cover off unless you disconnect that. So, now we'll take these bolts out, pull that cover off. Just take a couple pry bars and just pry this up carefully. There's a couple of pins that sometimes they rust that causes to stick in there a little bit. You grab this and you just slide it up. You just move this wire through. There we go. All right. Now, you gotta be careful of the bearings. There's bearings in between here. So, keep those in mind. And this piece comes out straight up. Now, this is a clutch housing. There's clutches right here, and there's also clutches inside here. And we'll check those out later. So there's a bearing right here. It's thrust bearing washer. Take that off. And then this is the reaction sun gear assembly. You twist that a little bit. There's a sun gear right there that comes out. Next are some of the clutches and the steels. These are the 2-6 clutches. Here's a plate in between.

Next is the reaction carrier assembly. Slide that up. There's some gears in there. And on the outside of here, there's some clutches. These are the low reverse clutches. Take these out.

There we go. There we go. And next is the input carrier assembly, and there is a washer, a thrust washer there, and the sun gear for that. There's a bearing under there or another washer. Now, this is the output carrier assembly. There's another thrust washer right there. And this is the output sun gear assembly. So there's the sun gear, and it goes into the output carrier assembly because there's some planetary gears right there. So that's why they call it a planetary gear set. So you have the sun gear in the middle, and then these are supposed to be like the planets, and those gears turn. That goes together like that. And this is the output gear hub assembly. There's another washer, washer bearing right there. So you don't wanna lose that. Now, this piece right here is the low reverse clutch assembly, and it is supposed to ratchet like this. That's exactly how it's supposed to work. And there's a lock ring that holds that in the case. You can just use a screwdriver. Just pry this out. This comes out just like this. It's just like a spring. And then this comes straight up just like that. And then these clutches are the 1, 2, 3, 4 clutches. Now, there is another piston in here in a spring. If we were having trouble with 1, 2, 3, 4 clutches, then we would wanna either replace that spring or even check it out, but we're not gonna do that at this time. So everything is disconnected or removed from this side of the transmission. Right now we're gonna flip the transmission over and split the case out. Now I'm gonna take all these bolts out around the perimeter, and there's some on the inside of the bellhousing. Now I can just pry these apart. Just be careful. A little tap right there as well. As you're prying, just give it a little tap. All right. Just grab that, slide it up.

All right. So here is where your differential is. This is basically where the axles are gonna go in, and this is where the power is gonna go to the wheels. Now, there is some bearings right here. So if you had some bearing type noise, it was from inside the transmission. Those could be bad. These bearings could be bad as well. Not very common. It's not something you worry about that often, but that's where they would be. This whole thing lifts up. This come out like that. And then you can check the race on the inside there, and then there's a tube. That fluid goes through that tube, and these separate as well. And this is where your park lever actually is. So, this is the lever. When you put the vehicle in park, this lever comes down, and that is what holds your vehicle from moving right there. Now, here is where the fluid pump is. This is what pumps the pressurized fluid throughout the transmission, and here is where the filter is. Now, one thing that stinks about this transmission, there's no way to replace this filter without doing all of this. You have to take the transmission completely apart to replace the filter. So let's break this down. How does the transmission actually work? This is the torque converter. Now, as the engine is running at an idle, the torque converter is not sending any power into the transmission. Once you raise the RPM and it starts to send power, it sends the power to this input shaft. So as the torque converter is spinning the input shaft, it's gonna go through the gears that are inside here into the assemblies, and then it's gonna come back out to this hub that is gonna spin the differential and go out to the axles and out to the wheels. So as you turn this, if I hold one of these assemblies, so spinning this in a clockwise direction as I'm holding this hub, you can see...as I'm holding this assembly, you can see how fast that spins. Now, if I hold a different one, spinning it in the same way, you can see the hub is going in the opposite direction, so reverse and then holding another one. You can see it goes a lot faster. So that's how you get your different gear ratios.

Now, how do you get these hubs to...or these assemblies to stop moving? That's where the clutches come into play. So you have these clutches that go around the hubs, and you have pistons that are gonna apply pressure to the clutches. It's gonna squeeze these together, and when these get squeezed together, that's gonna prevent this assembly from spinning, and that's how you get your gears. Okay. So how do you activate the clutches? So, as the transmission's spinning, these clutches are spinning. Inside here, you have a metal or a steel piece. You have a clutch that's got fibers on it on both sides, another steel, another clutch. So as the transmission's spinning, these are spinning inside here, and then you want these to squeeze swish together. So, we have something called pistons. There's a piston right here and a piston right here, and there's other pistons in here, and then there's another one inside there. So to activate those pistons, you wanna use low compressed air if you wanna check these. Around 20 psi is what you wanna do. So fluid pressure will go in here when you wanna activate the clutch, and that's gonna squeeze the piston just like that. There's another one right here. Just like that. You don't wanna put too much pressure in here because then you'll blow out the piston. That's how that works. So how do we get fluid pressure here? It actually comes from the valve body, the fluids routed from the valve body. There's different valves that open and close inside this housing right here. There's a top and a bottom. And that is actually controlled by these solenoids. So the solenoids will open and close and transfer fluid from one position to another, and that's controlled by the TCM itself. So these are electronically controlled. These are valves that will open and close. And normally shifting between gears, two of these will open or close at the same time simultaneously. So, if you're in first gear, two will be opened, and then very quickly, another two will open, and this will close. And that's how that works. And how you get the fluid pressure in there is actually from the pump itself.

So here is the fluid pump. And the fluid pump is driven by the torque converter, and there is two slots on the torque converter. And there's a chain that is actually in there driving the pump from the center of the torque converter. And this pump is actually being driven the whole time the engine is running. The whole time the torque converter is spinning, that pump will be pumping. So if I put a little compressed air...so when the piston gets compressed, compressing the clutches, this whole assembly will spin. And then there's clutches inside there as well. You can see that one's getting compressed right there. So if you had a problem with a certain gear, you could actually check all these and make sure that the pistons are actually working properly, or if they...you might have a leak, and it might not work at all. So in that case, those pistons would need to be replaced. Now we understand how this system works with the input going through the gears itself and the clutches turning on and off. Now let's talk about the output. So this hub, if you take this off here. Bring that over to here. A little bearing goes there. It goes right here. So that's spinning. After all the gears, that's gonna spin this. So this is the differential. This is where the axles go into, and that's gonna bring the power out to your wheels. And these go together like this. This is very heavy. It's gonna slide together. So when this hub is spinning, it's gonna spin this gear, which spins this gear which is actually attached to your axles, and that's what's gonna spin your wheels.

Now that the transmission is all torn apart, let's go over the individual components and what to look for and what could fail. So something you wanna look at...before you even take the transmission out of the vehicle, you can check the fluid. Drain some into a cup. Take a look at it. You're gonna actually smell the fluid if it smells burnt. Now, burnt transmission fluid actually smells horrible. You won't be able to stand the smell. You'll smell it, and it'll be very pungent. If it's not burnt and it just has a slight odor to it, it's probably...doesn't have any burnt clutches or anything. But also any metal fragments in there or any clutch material, you wanna take a look at that. Now, this should be a fairly bright color of red. This is...transmission fluid's a little bit dirty. And normally, if you have excessive transmission issues, a fluid change is not gonna fix your problem. There's probably more damage inside the transmission that just changing the fluid is not gonna fix it. The other thing you wanna look at is the fluid that's coming out of the torque converter. It doesn't look metallic-y at all, but if you saw a little metallic in it, it's not bad. If you see major chunks of metal coming out of it, that means there's another internal damage inside the transmission. The pump is probably not working properly or let go and sending metal into the torque converter, and then it's gonna have to be replaced. Now, if you had a problem where you weren't getting a certain gear or you had a slipping condition or you even had a code in the TCM that had to do with one of the solenoids, there is a way to test this solenoid pack. You put a special adapter up to this, and you use compressed air. Then you hook this back up to the vehicle, and when it's attached to the vehicle, you can command these solenoids open and close, and test them that way.

The next thing to look at is the pistons. Make sure the pistons are working properly. You can air-test them. You wanna use light pressure while testing these like 20 psi. And just check to make sure they're all activating properly. They're not gonna stay up. When you put a little bit of pressure there, it is gonna bleed off. That's just the way it is, but make sure you're able to activate each one of those. If you can't activate one of those when you're on your test drive, if you notice that you didn't have third gear or something, make sure whichever piston goes for third gear, test that, and see if it actually works. Now, if you don't see a lot of metal in the fluid itself or even at the magnet, you probably don't have any problems with the actual gears, but it's always a good idea to look at these gears anyway. If you saw a tooth missing or something, you're gonna have to replace this whole planetary gear set and same with the sun gears. Just take a look at them all just to make sure they look good. Normally, these are all okay, especially if they're lubricated properly, you know, in any of this area. These all look really good. I don't see any problems with any of these. Now, if you did have a vibration or a groaning noise in one of the different speeds, you might have something wrong with the gears, and it's not really common. But that's one of the things you would look for if you're looking for a noise or a vibration. Those all look good. Now, if you're having a problem with the pump, if you're having a slipping issue in all the gears, there could be something wrong with the pump, or if you had a pump-related code, it's a good idea to check the pressure in the pump before you take it apart and see if it's low. If it's weak, it probably needs to be replaced.

All right. Now we're gonna talk about the case. Now, if you had a component in the transmission that grenaded itself, something broke like the wave plate, and there was parts everywhere, and it was spinning around real fast, and it hit the side of the case and all, and you get some marks in the case. As long as it isn't like a crack or as long as it's not of any of the areas where there's machine components, then the case is probably okay if it hit anywhere in the sides here, and you didn't see fluid leaking. Obviously, if there's fluid leaking from it, then you're gonna have to replace the case. But also if you flip this over... Now, if you look at the case right here, you're gonna see some parts where there has been some damage, and that's from the clutches and stuff. But all these are just superficial. There's nothing major. If you saw one of the ears broken off, then there might be a concern right there, but anything you see here, that's fine, the case is gonna be okay. Now, with all the transmissions apart, it's always a good idea to replace the filter. It just kind of slides out like that. There you go. There's the filter. Now, if you saw that the filter itself was broken, or you saw metal on the inside of the filter in there, when you dumped it out, if there was metal, or even if you see metal in there, then that's not good. That means your pump is gonna have metal in it. The pump's gonna have to be replaced and then also your torque converter. If you see metal in those areas, you're gonna have to replace the torque converter. Now, when I mean metal, I don't mean just metallic-looking fluid. I mean like flakes or chunks. If you saw that, then those have to be replaced. And here if you look at the magnet on the old one...the new one has a magnet. It's nice and clean. This little bit of metallic paste is okay. That's normal wear for the transmission, especially with 100,000 miles on it. So we have a seal kit for this transmission. Now, I'm gonna replace all the crucial seals. Everything that I actually removed, then component that needs to be replaced, and there's gonna be some seals that I don't use like the valve body seal. Because I'm not taking the valve body out, I'm not actually touching the seal. So, it's gonna be okay in there. I won't have to replace it.

Just tap it down. There we go. Now, if you were replacing all the clutches, what you would wanna do is put them all in a pan, or at least most people do this, and take some transmission fluid and fill them up. Get all the clutches nice and lubricated. You can do that with each one. Some people do this, some people don't.

Now I'm gonna replace this 3-5-R wave plate. There's nothing wrong with the wave plate, but it is a common break on most of these older transmissions. And I know they updated the part, but while I'm in there, I'm gonna replace it anyway.

Here's our new TCM with the solenoid pack, and you can see the membranes are not broken in this one. So that's good. It already has this seal on the back. So we don't have to replace that.

Now with the transmission all back together, I can bolt it to the engine. Let's get this [inaudible 00:47:37] right there. At this point, now we can get the transmission mount secured so that the transmission is supported by the cradle. Now I need to install the torque converter bolts. Now, I need to index the flywheel. Right here if you look at this hole where the bolt is gonna go through, it's not circle. It's oval. Now, that's gonna index it. So this is the first bolt that you put in. If you did not turn the flywheel to get to that position, then when you put the bolts in and you tighten them up, when you go to spin it, the other bolts are not gonna line up. So, now that I did that, I can tighten this bolt down and then turn and add the other bolts. Now I've got those torque converter bolts in and torqued. Next, I need to put the starter on, put some of the sensors back in, plug in some of the wiring, put the transfer case back on the backside of the transmission, and then we'll be ready to lower the body down onto the cradle.

All right. Everything is buttoned up with the engine, and transmission should be all set. I am gonna leave the alternator out. We struggled when we dropped the powertrain down from the body. This way it'll make it a little easier, a little bit smoother going in. So, at this point, we can drop the body down. Now that the body is lowered down onto the cradle and the powertrain, now we can put the cradle bolts in. I might have to adjust the cradle a little bit just to get everything to line up. That's what we're gonna do next.

Now we're gonna put together everything underneath the vehicle next like the driveshaft and the suspension and everything else that goes with it.

Now we're gonna get everything up top back together.

So we're still gonna need to top off all the fluids, and we actually have to have the vehicle towed to a dealership because they need to program the TCM. We don't have the ability to program it. They're gonna have to do it. I hope you enjoyed this video. Please subscribe to our channel. Make sure you ring that bell. Turn on all notifications so you don't miss any of our videos.

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