The Basic Parts of an Automatic Transmission (Part 1)

greetings viewers Eric car guy here back again with another fun-filled episode say fun-filled because I know that a lot of you viewers really enjoy these videos where I tear things apart and today we have a an automatic transmission out of Toyota Corolla I'm not really sure I've actually had this transmission sitting around for about two years now waiting to do this video so today's the day today is the day I tear it apart and this may end up being a series of videos what I'm trying to do in this one is just sort of give you a general overview of what the parts are I'm not going to claim to be an automatic transmission expert although I have taken them apart I do know the parts on the insides of them normally what I run into a situation where I need to deal with the automatic transmission that has failed I just replace it I don't normally go through the process of rebuilding it and if you do find yourself in that position strong and I can recommend that you go with a rebuilt transmission and if you're looking for a place that is going to rebuild your transmission for you one of the key things I think that that you should look for in a place that rebuilds automatic transmissions is that they have a transmission dyno and what that does is that's actually something that they can hook the transmission up to and run it before they ever put it on the car usually these places they build enough transmissions to know what they're doing to give you a quality rebuild and that's that's really important because the automatic transmission is by far and away the most complex component on a vehicle so there's a lot of things that can go wrong if it's not done properly and there's a lot of work to get that thing in and out of there on top of that so you want to make sure that it's done and done correctly but I've sat here and talk for long enough so let's go over to the transmission and just get a general overview of the things that are on the outside of it just to get an idea of some of those components that we can see externally that's uh let's head over there now okay let's first get a look at the outside here and just sort of put a name to some of this stuff and the first thing that that we're going to see is the torque converter and this is the component that actually bolts up the flex plate on the engine and wrote and basically feeds power to the transmission and it does a couple of things it provides like a fluid coupling between the engine and the transmission itself it also powers the front pump and it also multiplies torque in fact I think I'm going to do a video just on the torque converter itself this little arm here is not normally here it's basically just there when you put an automatic transmission in to transport it from one place to another so you normally normally you just don't see that now going back round the outside here we have the dipstick and these cooler lines which will normally be hooked up to a transmission and this these are the lines that send transmission fluid to the cooler inside of your radiator some even have an external cooler and I could just pull that out like that which is kind of convenient on the outside here we have what what I often call a PRNDL switch and I say that because Park reverse neutral drive but it also drives the manual valve and each time you you change like you put your car into a particular gear I think that's probably parked there reverse neutral drive second or low C Park reverse neutral drive second or low one of those too so this would be connected to probably that the lever on the console and this one or sometimes it'll be on a column shifter but there's basically a cable that moves this for gear selection this switch here many times has your reverse lights in it it also tells you what indicate gives you the indicator on the dash but more importantly it sends a signal to the PCM or transmission control module there may be a separate computer for this and tells it what gear you're in because many times especially newer transmissions are not only hydraulically controlled but they're also electronically controlled now this guy here is a long cable and that cable will connect to the throttle right next to the throttle cable and it is called actually a throttle or TV cable and what it does is it sends a mechanical signal to the transmission and tells it how far you're into the gas so there are times when you're just cruising down the road and you step on the gas and the transmission will shift at a fairly reasonable place so the gears will come like at lower speeds but say for instance you want to accelerate hard well this cable signal or the signal that comes down to the transmission basically tells it to hold those gears longer because you're looking to you know get maximum acceleration and then everything in between so it knows how far you are into the throttle via this mechanical connection newer transmissions use a lot of electronic controls for this so this this I believe is some kind of hybrid in between the two that it it has a few components that are mechanical and a few components that are electronic and they're all mixed together to basically get you down the road wasn't kidding when I said these things were complex now I'm hoping to open this thing up and find a planetary gear setup but I really don't know I've never been into one of these transmissions before the only thing I do know is that this transmission failed second gear was the problem it didn't have second gear so I expect to find some issues with second gear when I get in here spinning it around this is where your axle goes in for one side and the axle on the other side goes in here so that would make this portion here either the differential or the final drive of the transmission so in essence you could look at this portion as the same as that axle assembly that you see in the back of a rear-wheel drive car but it's just compacted together in fact what they would refer to this as is a trans axle and part of that is is because it houses the final drive or differential assembly in addition to all the components of the transmission now this guy here I dunno what this is this is the speed sensor and this sends a signal to you not only your speedometer but it also sends a signal to the the transmission computer to let you know about how fast you're going aside from how far in your throttle the computer also wants to know how fast you're going to decide when it is that you need to change gears or when it is for the torque converter to go into lockup we'll talk about that possibly in another video as far as the torque converter because that in and of itself I think would make a good video once again it's an electronic sensor I've actually done videos on the diagnosis of these but but you'll find that it it's tooth or Earths has a set of teeth that goes to the final drive that will be able to get a better look at here at some point so the speedometer is always flying to the final drive one more thing up here this is a vent anytime you have gears moving in a closed space you need to vent the case so whether it's a differential whether it's a transmission or an engine and uses the PCV system anytime you have moving parts inside of an enclosed space you need to vent it so sometimes these vents will get clogged and when they do get clogged they will actually cause the seals of the transmission to leak because pressure will build up on the inside of the case so if you do have a vent like this make sure it's not clogged and make sure it's in such a position to where it can't get water or something in here sometimes they have a check valve or something on the inside of these to prevent any kind of water intrusion but some are just vents and if they are just vents and there is water that gets in there what our transmission fluid not so good it ends up looking a lot like a strawberry milkshake the first thing I'm going to remove is the torque converter now this guy here like I said deserves a video in and of itself and I'm going to make a video just on the torque converter but for now I'm going to remove it from the transmission so you can get an idea of what's what's behind it and it just rests in here it's just pushed into the bell housing you know sort of shaped like a bell and it just slides right off of there it's really kind of a cool thing we'll get a look inside that another video now we are inside the bell housing this would be the input shaft to the transmission and also inside behind here this assembly here is the front pump this is basically the heart of the transmission everything about an automatic transmission relies on pressures and those pressures well at least the volume of fluid remember pressure is not created by pumps but the volume of fluid is created by the pump and this is driven by the spinning motion of the torque converter so this basically pumps fluid all throughout the automatic transmission and allows it to work one thing it's important to note is the identification of the transmission itself many times transmissions are identified by the amount of bolts and the shape of the pan for the filter not all transmissions have these pans but also there may be a tag on the outside here and this this should basically tell us anything we need to know about the transmission or at least I think so there may also be casting marks on the outside of the bell housing there's there's lots of different ways to identify them I would consult the service manual for the vehicle that you're working on to know exactly what those numbers mean but like I said many times transmissions are identified by the pan which is up underneath here that we really can't see any amount of bolts on the outside of it and then they're also separated by a three-speed 4-speed 5-speed and you know they're all the way up to 8-speed now in some transmissions but this one I believe is a four-speed automatic transmission right here's the pan that I talked about and we're fortunate enough on this Toyota to have a drain bolt to where we can remove that to drain the fluid out without having to pull the pan to do it I really like it when I see these drain bolts but once again to identify an automatic transmission many times its identified by the shape of the pan and the amount of fasteners around the outside of it I'm going to see if I can remove this upper assembly off of here I'm going to start by removing these fasteners around the outside now I'm going to get the ones that are there in in the bell housing itself once again I'm not a mattock transmission expert I'm just going to take this apart and basically tell you about the parts that I know about these came out a a little more difficult because they have Loctite on them apparently Loctite is almost like a glue and it's basically there to prevent fasteners from backing out normally I think there would be a puller assembly that would go across the front of this that we've run down into here and pull this pump assembly right on up out and honestly I don't know if my technique of prying this bell housing assembly off of here is going to be as successful as I hope but we'll find out and it's just a dissection so I'm not too worried about it all right let's employ the trusty pry bars and see if we can find purchase I think it's going to cooperate find a nice little ear right over here I could slip under there we go check that out this is the back side to that pump assembly and you see we've got like lots of teeny tiny little bearings and everything down in there I'm going to see if I can get the backside of this pump off because I think it's important to show you how this pump looks on the inside so you get an idea actually how pumps like this work most oil pumps are of this type and they and you can really get a feel for for how pumps work in general just by looking at that now we're on the inside of the transmission itself and this is kind of cool in trying to see well this one's a little bit different once again we're looking at the input shaft this was the thing that actually went into the torque converter and once again it drives the front pump but it also drives the assembly in here the gear assembly which I'm hoping we're looking at a planetary gear setup because that's what is in most automatic transmissions or planetary gears and I think that's what we're looking at so I'm a little bit excited this right here is your differential or final drive assembly so the power is delivered inside the transmission and then the gear is selected depending upon you know lots and lots of conditions and lots of things and it outputs here to what looks like a counter shaft in this particular case and then that counter shaft is spline to the final drive so this is what drives the axles which drives your wheels and this right here this guy it's funny that it's got a little bit of slop to it that's what splines to your speedo gear one grab that real quick remember that our friend the speedometer well he was sitting right here and you can see how it slides right up to that and as as the spins this this rotates and is equated to a vehicle speed you can calculate all those things using special math it's not really special it's uh just algebraically but I think what we can do now is just lift the carrier assembly or at least half of it yeah the carrier assembly right up and up out of there there's your differential these are the called the spider gears and they basically make it so that the wheel with the least amount of traction gets power will go into differentials in depth at some point but but the long and the short of it is is this is what the axles go into and that's your final drive then we can get into the meat and potatoes of what we're looking at here and this this is I believe the parking gear so what happens when you put your car in park as you see these little notches around the outside of this assembly well when you when you've got it in park this comes in and locks into place and that's it this this is one of the things I wanted to show you about what's inside an automatic transmission and that is that this is the only thing holding your car in place when it's in park so yeah it locks it locks the gears and everything into place but ultimately that's it so the lesson here use your parking brake because I got to tell you just that little piece right there doesn't seem like a whole lot yes it does its job but for me the peace of mind and knowing that it's not just that that there's also my parking brake holding my vehicle in place makes me feel a whole lot better it really does it looks like I'm going to need two hands to start lifting these components out of here to explore the rest of what we have you know I just thought of something before we go and start taking apart the internals of the transmission I'm going to see if I can get this pump apart you can see that this is a washer probably a thrust washer is what it's called and there's lots of these there's lots of these o-rings too which are also very important because once again pressure is everything in an automatic transmission and that pressure is directed to different places and held into place by these different seals these seals are made by a lot of are made of a lot of different things and I believe these are teflon seals I'm trying to see if I can get one of these off here for you in fact when you rebuild an automatic transmission you'll find that there's a whole lot of seals as being one of them type of seal that's in here and this isn't exactly rubber it's made of I believe teflon and they seal off I suspect an oil passage yeah this hole right here that directs pressure to something I'm not exactly sure what but it's over in in the clutch drum inside there and that pressure goes from here into that clutch drum and is held it is sealed in place by this so when an automatic transmission fails there are a lot of different things that can cause it to fail and a failure of one of these seals is one of those things so if it could be like a clutch or a band or something like that or maybe even something electronic that's caused it to fail but something that is sometimes overlooked is a failure of one of these seals in fact a very common failure for torque converters and the torque converter clutch you'll he probably have heard that before is the seals going to the torque converter clutch itself there's pressure that's directed inside the clutch compared the torque converter clutch to activate the clutch inside of it and if the seals around the outside of that go bad that pressure bleeds off past those seals and that torque converter clutch never activates now I'm not saying that that's what these seals go to they actually go to the drum over on the transmission which I'll show you here in a minute but I just wanted to show you some seals and the importance of those seals in the transmission let's see yep we're going to get a look at our pump assembly very happy about that this is your pump I'm just going to set this other part of the housing this is the back side of the housing sits in here in fact this these little teeth right here or what the torque converter splines - I believe as a result it rotates this assembly and you are looking at an oil pump you're looking at the heart of this transmission also so right there is an oil pump you like why and most oil pumps look like this they're just like a couple of gears that spin and the way they work give you another look here where they work is and sometimes these teeth are keyed so you have to make sure that you know there may be a dot here and a dot here you have to make sure that those line up in order for this to work so as the engine rotates it drives the torque converter which I believe is splined right here - this inner gear on this pump and it turns this assembly and as a result what did it what it does is because of these gears meshing together here it creates a low-pressure zone and it draws the fluid into this area well that's then moved through to the other side and pushed you know through so it creates a volume of flow remember once again pumps don't create pressure valves and Springs and resistance to the pump flow creates pressure so this just creates volume but this in essence is how the front pump on the transmission works it's flying up to the torque converter torque converter spins this and voila there you go here's the back side of that pump you can almost see where the fluid flows in and flows out and that's exactly what it does and because of those tight spaces it moves that fluid around and here is our torque converter and these are the key waves I'm talking about here so look at that that's what that's working burgers driving so that torque converter spins the oil pump and muj fluid through the transmission kind of cool huh okay before I put this under the bench I want to point out one last thing bearings these are roller bearings if you've got a noise inside your transmission it's possible you have a problem in the bearing and this one looks like it's just held in by this retainer so be easy enough to take out but these these bearings help support things like this one in particular supports this counter shaft here so bearings are another comporting component to automatic transmissions and you have to inspect them for any damage or pitting or anything that could possibly cause them not to to make noise or to maybe they failed it's not something you see often but it is something that to watch out for now I think I actually think I can take this this portion out here I hear this drum and I'm just going to lift it on up out here looks like I'm going to have to undo this band and there's a couple of things that that control an automatic transmission or help activate the different gears and they use a couple of different things they use clutches and they use bands many times and right here we have a band that's on the outside of this drum that I'll actuate this this assembly I'll give you a close-up look here now hopefully you can get a better look at what I'm looking at here and there's around the outside of this a band around the outside of this drum and depending upon I'm going to have to look at it and find out what gear is what normally a lot of times second gear is is controlled by a band and what will happen is as you can see this actuator here there's a little pin there when there's pressure directed to it through the valve body and it's told to shift into whatever gear this is which I want to say maybe is second gear it activates this and this band is cinched around the outside and holds this thing in place so it may normally spin in fact I've got a little bit of spinning here with the main shaft but this this may normally spin but when the band holds it then this part of it is not going to be able to suspend and there may be something else on the inside that is and that helps dictate what gear ratio you're in and that's not a really good explanation I think it's a lot easier if I show you the actual gears what my point is is I wanted to show you that there is a band around the outside of this assembly I don't want to see if I can pull this pin maybe and release tension on it so I can lift this on up out of here now it looks like the easiest thing to do is just to take this pin out and once I do that the band should come loose which it just did you saw it fall down there you should be able to pull this right up out of here cool that is a clutch on the inside of that so on the outside we have the surface where the band holds it and on the inside we have an actual clutch assembly which we can take apart and get a look at here why don't we just take this band out of here while we're at it just like I said it's a band it goes around the outside of this drum and when activated it holds this drum in place so when activated its it's pinched up tight and as it pinches up it keeps this thing from spinning you can see the sort of shiny surface on the outside of it and there's a material to help it grab hold on the inside here now sometimes well many times bands are adjustable so you adjust that the tension on these things to be just right so that they they operate properly what else can we pull out of here ah yes it is a planetary gear assembly I'm so happen I'm going to pull this out and I'll show you how it works right here is the planetary gear assembly we're going to talk about this here in a second another parts of that planetary gear some in fact this center gear here is another important component which has yet another gear on the opposite side of it it's like we've got a giant snap ring holding in the rest of this a lots of things inside trance automatic transmissions are held in by snap rings here's one of them return Springs on that on this disc we've got some clutch pieces in here other inside to a clutch assembly the splines on the outside are also important because in this case they are spline to the back of this assembly and then they dictate whether this rotates or not or is engaged or disengaged depending upon what gear were let's talk a little bit about clutches real quick okay here's a set of the clutch and for those of you that do any work on motorcycles and have seen motorcycle clutches virtually identical in fact you may be looking at just thinking the same thing we've got a series of steel rings and then you've got to set a friction disk and then they go in layers like like a sandwich and how this works is is when this is inside of an assembly like you saw down inside the transmission is pressure is directed on the outside of this so that these things get squeezed together and as they get squeezed together they can activate a component within the transmission such as what we have here because the fact that it's flying to this means that when this clutch is active it's going to make this component either spin with what's happening or not spin depending upon whether there's pressure or not then you have returned Springs to where when the pressure is released this helps push everything apart so that it disengages because not only do you want to engage things but you also need to disengage things inside the automatic transmission

Channel: EricTheCarGuy

Views: 1,587,650

Keywords: automatic transmission, torque converter, clutch drum, clutches, planetary gears, accumulator, o rings, teflon seals, transmission pressures, manual valve, sun gear, planetary gear, ring gear, valve body, valve body operation, transmission fluid, main shaft, counter shaft, bands, automotive education, how to, eric the car guy, ericthecarguy, etcg

Id: JGbsgpp2YJQ

Length: 28min 13sec (1693 seconds)

Published: Mon Feb 18 2013