Chevrolet Bolt EV Traction Motor – Deep Dive

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Chevrolet Bolt EV Traction Motor – Deep Dive

Hello, I’m professor John Kelly and this is the Weber Auto YouTube channel In this episode we will be disassembling the drive unit the electric motor and gear reducer out of our 2017 Chevrolet bolt on the hoist behind me here. now this drive unit and electric motor combination is is all one piece, unlike the Nissan Leaf that has a drive unit that unbolts from the electric motor. This drive unit is rated at 150 kilowatts which is 201 horsepower, it is also rated at 360 Newton meters of torque which is roughly 266 foot-pounds of torque Now let’s let’s talk about torque just a little bit. That torque rating is what the motor itself is capable of producing, that is not the same as the torque that ends up at the wheels of the vehicle, so for example the Chevrolet Spark EV produced by Chevrolet before the Bolt here actually had an electric motor that produced 540 Newton meters of torque, the Bolt EV electric motor only produces 360 Newton meters of torque and so you might be misled into thinking that the Spark EV had more torque; well, the motor did, but not the torque delivered to the axles that drive the wheels. So the gear reducer right here on the side of this drive unit has an impact on that because gear reduction is also torque multiplication minus frictional losses, so the Spark EV had a 540 Newton meter electric motor but it only had a three point one five to one gear reduction unit which resulted in about 1700 Newton meters of torque at the wheels, at the axles. the Bolt EV electric motor produces 360 Newton meters of torque a whole 180 Newton meters less of torque from the motor, but it has a seven point zero five one eight to one gear reduction through this gear reducer which multiplies that 360 Newton meters of torque by seven point zero five one eight, which gives us over 2,500 Newton meters of torque at the axles. So there are other electric vehicles out there that are being produced right now that have higher torque higher motor torque than the Bolt EV but what would be interesting, I and I don’t know what their gear ratios are yet, is to see what is the torque actually to the axles what’s the torque to the ground because that’s what you’ll feel when you step on that accelerator pedal, that’s the torque to the wheels that makes the vehicle move. The design of this drive unit this electric motor it has a peak amperage draw of 400 amps versus 450 as for the Spark EV so it uses less current to provide more torque so it’s a more efficient better design electric motor. The electric motor in this drive unit spins clear up to 8810 rpm where the Spark EV only spun up to about 4500 rpm, and we’ll take a look at some differences in the electric motor design and the stator winding design that allowed it to spin at those higher rpms without the AC losses that typically occur at higher rpm. As mentioned in the previous video on high voltage components of the Chevrolet Bolt EV this drive unit uses about 2.9 litres, around 3.1 quarts of Dexron HP fully synthetic base transmission fluid automatic transmission fluid. It also is cooled by the General Motors Dexcool 50/50 mix of coolant and deionized water. Okay let’s take a look at the outside of the housing here of this drive unit. The official name or designation of this drive unit by General Motors is the 1ET25. The one means it’s a one speed trans axle, this doesn’t shift, E means it’s electronically controlled, T means it’s a transaxle, and the 25 is a relative torque rating. Alright, right here on the front of the transmission is the actual last eight digits of the

vehicle identification number and you can see that MMF right there, that is the three-digit regular production option code the RPO code that you can find on label in the back of the Bolt EV if you take out the lower compartment carpet and look in what looks like a spare tire tub, there’s a label on the driver’s side that has a whole bunch of three digit codes on it MMF just means that’s which transaxle or transmission this vehicle came with Okay right here on the top of the trans axle is the transmission range selector actuator and this is a brushless DC motor with a gear reducer that actually moves the shift lever to put us in to Park reverse neutral Drive and low, now technically inside of this drive unit it there’s really only park and not park, but there is a position sensor in here called an internal mode switch that will monitor which position the transaxle range selector is in so that the vehicle can act appropriately. For example the shifter itself on the center console is not directly connected to the drive unit, it’s just an input to the computer that controls this actuator, so when we go to the reverse position for the neutral or drive or low, there’s a feedback on the internal mode switch electrical connector right here, that lets the engine control module, even though this doesn’t have an engine, know which gear range you have selected so that it can request the trends axle act appropriately. Also, right here by the electrical connector for the internal mode switch is the transmission fill plug, so if you want to put fluid into this transmission you need a 14 millimeter wrench or socket to take this plug out and put the Dexron HP fluid into the transmission. There are two drain plugs on this transmission, one for each side, so there’s one down below on each end of the transaxle the driver’s side and the passenger side, there’s there are two separate drain plugs to get the fluid out of each side, now there’s only one fluid that goes throughout this entire transaxle but because of how its baffled and set up inside to remove all the fluid you need to remove both plugs Now speaking of fluid and fluid level when you drain fluid at whatever the recommended fluid change interval is or if you’re doing service work on the transaxle here and you’re adding fluid you need to know when to stop adding fluid, so on the other side of the transaxle right here is the transaxle fluid level check plug, so the drain plugs right down here, the fluid level check plugs here, the fill plug is on the other side so you take the fill plug out you take the fluid level check plug out, and you add fluid until fluid comes out over here, and then you let it sit and stabilize for a minute add a little bit more and make sure that fluid comes out comes out to a slow drip, and then the instructions tell us to put both plugs back in and go drive the vehicle until the transmission fluid temperature reaches 35 degrees Celsius or 95 degrees Fahrenheit and then double-check the fluid level again to make sure that comes out at a very slow drip. Alright, while we are here on this side of the transaxle we have an electric motor an electric pump for the transmission fluid so there’s a big filter we’ll see when we take this thing apart down the bottom center of this transaxle it will pull fluid up from the filter and then put it into what’s called the oil sump so the oil sump is basically just a great big bathtub looking area up here that the pump fills full of fluid and then there are these little drain channels that fluid drains down to cool the stator windings and lubricate bearings and so on and we’ll see that once we get the cover off so we have an electric 12 to 14 volt driven electric motor that pumps fluid throughout this transaxle. From what I read this pump only works when you are in Reverse or Drive, it does not pump when you’re in park or neutral Alright, we have another electrical connector right here, this connector is for the resolver which measures the angle of rotation the direction of

rotation and the speed of the electric motor rotor itself, and then there’s a transmission fluid temperature sensor that is in the bottom of this transmission case cover here. All of those are accessed electrically through this electrical connector right here. As you may have seen in my other video on high-voltage components we have the air conditioning compressor of the bolts up here and then we have our coolant pipes that go into what’s called a coolant sump in the bottom of this transaxle and we’ll see that here in a few minutes but we have coolant going in coolant coming back out and goes through a series of cooling fins and cooling circuits to absorb heat from the transmission fluid right here on the back we have the electrical connection for the three-phase cables that come from the the single power inverter module that sits two modules above here. Three-phase orange cables come down to drive the electric motor, there’s a cover the cables bolt on and then there’s a cover they’ll holds the cable in place We have a transmission vent right here, let’s just take that vent off while we vent tube off while we’re here now you can see the oil sump area again on the top and the cooling sump coolant sump area here in the bottom all right there is one additional plug on the side of the case with the electric motor and there’s nothing in the service information to indicate this but I believe this is a pressure test plug to check the pump output pressure, but I can’t find any information on what that fluid pressure should be. Okay, I’m going to be disassembling this transaxle right here on the workbench but there actually is a special fixture to hold this transaxle and allow you to rotate it and disassemble different pieces of it and still be able to rotate it for convenience. I have this special adapter as you can see here in this photograph but the way it’s mounted it’s too high and too difficult for me to disassemble in that holding fixture being in a wheelchair, so the workbench is where I’m going to disassemble it, but I wanted you to know there is a special fixture for that and I tried it it just doesn’t work for me by the way this transaxle weighs about a hundred and seventy pounds or 77.4 kilograms. Okay, well we’re ready to start disassembly, the first step is to remove this oil pump the 12-volt power oil pump, it has three bolts right here and a few seals underneath it as you can see here there are two seals that seal the pump to the transmission case right here there are two bolts that hold the cover over the pump gears themselves there are no instructions on disassembling this so I assume we’re not supposed to disassemble it but that’s exactly what I like to do take things apart I’m not supposed to as long as I can get them back together and make it work again here we go we’ve got a Jew rotor style oil pump there’s an o-ring right here that needs to fit in this groove to seal and then the cover just bolts on okay the next thing on the list is to remove the left-hand and right-hand output shafts that go into our differential side gears in the gear reducer this is the left-hand side right hand side over there it calls for a slide hammer and a old pilot bearing removal tool for a manual transmission so this is the pilot bearing removal tool right here and a slide hammer and we are supposed to put this up inside and put it into the snap ring groove for the CV shaft and then pop it out well come to find out the snap ring groove is thinner than the tip of this tool that’s supposed to go into it and I didn’t realize that’s what the problem was and I had a hard time getting these output shafts removed I finally got him out but once I got a mound got looking at the tool versus what they were supposed to be grabbing I realized I need to grind these down make him a little thinner so that they’ll actually fit into the grooves of the her for these CV shaft snap rings that are there so since I’ve had this entire transaxle apart before

and I’ll put it all back together I’ve removed those snap rings they’ll hold these output shafts in place so I can just pull them out by hand right now this big long left hand output shaft goes right through the center of the rotor of the electric motor itself it’s it’s hollow in the middle and it has a big heavy-duty bushing right here on the outside with the axle seal and this is our left-hand output shaft and then the CV shaft itself plugs into here that goes to the left front hub and bearing assembly and tire and we’ll assembly so there’s our left-hand axle shaft there’s a snap ring that fits in that groove right there typically and I’ve just removed and I’ve just removed that snap ring for ease for this demonstration here obviously I’ll need to put that back in when I reassemble so that’s the left-hand axle shaft on the other side we use the slide hammer again and pull out the right hand axle shaft as you can see this one is much shorter than the other one and it has the support bearing in the differential case itself that holds it in place and its own snap ring that I’ve already removed and of course an axle sill here on the other side as well okay the next thing on the list is to remove this transaxle case to remove the case I’ve got to take the linkage off and our actuator off and then we’ve got these bolts to go all the way around and then we’ll be able to see the gear reduction transfer gear and the final drive ring gear and differential gear set so I’ll take the clip out and lift up for a linkage on the shift actuator and then take the bolts out okay here’s the shift actuator assembly itself transmission range selector actuator kind of a great big piece I I’ve seen some of these that are smaller right I’m not sure why this one is so giant I’m not I’ve never seen one this big but it obviously does the job of mechanically shifting the transmission range lever since you have an electronic shifter on your center console alright let’s take these bolts out of the trans transmission case okay I’ve got all the bolts out of the transmission case now we can attempt to slide it off it has a couple of dowel pins they’ll hold it in place there’s a couple of pry points plus one right back here and another one right here there we go I’m going to come in with a plastic mallet here and just tap lightly there we go okay we can see inside of the transmission case itself and the only things in here of real interest are the transmission internal mode switch right here we got the electrical connector right here harness right there that connects to this outer blue connection connector that will read which Range Park reverse neutral low you have selected with your transmission shift lever and then we have the parking linkage right here we’ve got Park reverse neutral Drive and low now of course normally transmission fluid would would be pouring out of here of whatever didn’t get drained out when you drained it previously but I’ve had this apart and cleaned everything up before we have our ring gear right here and our differential gear set and as notice we have real nice ball bearings here these

bearings since their ball bearings instead of tapered roller bearings have to have in place shims so there’s a special shimming procedure to control the end play of these bearings that will have to go through when we reassemble it so you’re supposed to take these shims off and throw them away well and then replace them with new new ones when you go back together I suggest that you take them off and measure them and then hang on to them because you might you might need them again when I took these off previously and measured them they were almost all identical in the thickness so there are six of these shims for the six ball bearings that are in this transaxle four of these shims measured exactly half a millimeter in in with the other two one of a measure one millimeter in width and the other one measured 0.9 millimeters so you need to keep track of what thickness shim you had where and write those down so that you you’ll have an idea of at least what it was before you took it apart now if you’re just going back together and you haven’t changed any shims or any parts inside just reuse the old shims but if you’re changing a bearing or any of these internal pieces you need to go through the special measurement procedure that we’ll see when we go back together to determine if these shims are correct okay so there’s there’s special shims on each of these bearings I’ve measured all of them RIT written their dimensions on the ziploc bag here that I keep them in and will refer to those when we go back together all right now we just need to remove the counter gear right here and the final drive a ring gear and differential gear set this is where our short little output shaft plugged in right here and then our long one came all the way through on the other side okay before we remove these gears there is a an aluminum gasket with a rubber seal embedded into it the instructions tell us that is not reusable there is also an oil baffle right down here to channel transmission fluid away from the ring gear to reduce losses as it rotates into it and to splash oil up into different channels to lubricate the the bearings if we look in this case half right here you can almost see what looks like a funnel right there for the fluid to drain back down and lubricate this outer bearing and a similar one here on this other other side for that bearing so we’ve got a oil baffle to remove all right I’ve got the oil baffle removed on the other side of that is our magnet for metallic particles from gear normal gear wear and other malfunctions okay now we’re ready ready to remove these gears pull out on the counter gear and then pull out on the final drive and it’ll come right out if you don’t pull out on that counter gear first there’s not enough clearance for the final drive Unit two clear so here’s our final drive you can see our open differential gear set inside there here’s our sim on the other side as well all right the instructions tell us that we can if we won’t want to remove the park linkage in the internal notes which I don’t really care about that that’s just regular stuff that you’d see in any other automatic transmission so let’s continue on with things that are unique to the bolt evie drive unit here the one ET 25 transaxle so let’s turn the transmission case around and we’ll take off the transmission case cover here on the driver’s side now the SAE document the details the the bolt evey drive unit here that I told you about in the high voltage component video tells us that the drive unit

itself was designed to be serviceable in the vehicle that’s why they have a case removable case cover on one side and a case cover on the other side for the gear reduction unit you can leave this Center portion with the electric motor in it in the vehicle and just remove one or both case covers to do service work on components inside the case covers seal replacements resolver replacements internal modes with replacement and so on but anyway we’re going to take off this case cover next from the driver’s side all right this case cover is going to be a little harder to get off than the other one because the rotor that has internal magnets embedded inside of it has now magnetically pulled itself over to the stator because we are no longer centering it inside of the stator itself and so it puts a it pulls it off to the side just a little bit so there’s a prying right here and there’s a pride point right down here another prior point right here there we go okay so here’s our case cover and it has an aluminum gasket that’s not reusable as well our case cover has this long transmission filter that’s not serviceable without disassembling things as you can see has a temperature sensor down inside of it right there and then this is our resolver our serviceable resolver that measures the position speed and direction of rotation of the electric motor rotor inside the transaxle here let’s turn this around oh by the way down inside of the bearing housing there is a shim for the ball bearing right here on the rotor itself so we’re looking at the stator and the hairpin six conductor deep stator design a unique design we’ll talk about that a little bit more once we get the stator out we have a lubrication channel right here where fluid is going to drip out of our oil sump and run along and drop down on to the stator windings themselves and cool the the stator windings it also has a drip channel that comes over and goes down to this bearing here to lubricate it so we’ve just got an 8 millimeter head bolt holding the filter in place and as you can see the filter just has an o-ring seal on the one side and you can see the pick up filter screen filter element on the inside so this is going to reach all the way in up underneath the the stator itself to pick up the fluid on the back side of it and on the back side of it is the inlet of the coolant so that would be the cooler oil on the back side there all right then on the resolver it just has eight three eight millimeter head bolts to hold it in place and one electrical connector this resolver only bolts in in one location it’s not adjustable it has automatic learn unlike the older Toyota Prius resolvers that that would actually come out of alignment if you unbolted them and there was no way for you to line them back up okay so here is our resolver pull back on the connector position assurance clip depress the tab and remove the resolver itself the resolver is a serviceable unit when and if it ever goes bad but it should should never go bad all right then the remaining wire harness and the pass-through connector here just goes over to our temperature sensor okay next on the list we need to remove what is

called the center support this is what’s supported the driver’s side ball bearing of our differential case assembly okay this is our center support it’s held in place with six bolts and aligned with two dowel pins right there now with that removed there’s nothing to stop our transfer gear from sliding out it’s just a tight fit on the bearing in the bore as it should be just pray lightly sometimes these will just slide right out and right in and other times they’ll they’ll fight you here we go okay so here’s our transfer gear it’s ball bearing and shim so put that shit over here with the others okay right here in the end of the case we still have a lubrication channel right here from the oil trough the oil sump I mean right there and then we have a cover for the three-phase electrical connector right here as well then on the other side we have that oil distribution channel right here that cools the stator so we’ve got to remove that we are now to the point where we are ready to pull this rotor out but we just can’t grab on to it and pull it out it has some super strong neodymium magnets multiple layers envy configuration inside of this stator you’re not going to pull it out by hand and you sure don’t want to come in here and start prying on it so the only way to get that rotor out of there if you want to remove it for service replace a bit bearing on it or the gear on the other side or another bearing or just replace the rotor itself for whatever reason loss of magnetism and trouble code sets or whatever it takes a special tool to pull it out without having it rub on the stator frame itself and without having it injure you with you trying to pull it out and it’s pulling back in with all its magnetic strength so true get that out there’s a special guide tool that will hold it centered in the stator and we need to set that up next and it starts on the other side here so there’s a special tool kit that costs almost a thousand dollars to Center this rotor as you pull it out I found one on eBay for a little bit less than that but but it’s a very expensive tool but if you want to do service work on this transaxle you’ve got to have it so let’s bring in the special tools okay so I brought in the special tools to keep the rotor centered there’s a special spacer with a notch in it to clear that notch right there this is just gonna fit in there just like that then there’s a plate that bolts on over the top of this to hold it in place these don’t need to be super tight they’re just holding that little spacer in place so I’ll just lightly Snug those up then there’s a sleeve here that’s supposed to fit down the center of that rotor but these sleeves are a little bit too big I’ve had to take sandpaper and send them down to make them fit inside of this rotor and I don’t know if that’s because the tools were made for a first design rotor and then they changed it or if they just made the tools incorrectly but these tools are from what used to be can’t more tools the special tools supplier for General Motors it’s now Bosch service solutions so Bosch you may want to take a look at this this tool here the DT five two zero one one – one – three because it doesn’t fit it’s not doesn’t Center up inside the the rotor as well as it should i’ve had to sand it down just a little bit and then i’m able to tap it in a little bit there but I think that it’s

supposed to be if it’s supposed to be a tight fit but it should be able to slide in by hand I believe then we have a guide pin that’s going to go through the center of that then we have this outer housing the bolts in place to hold the guide pin in place so the blue sleeve this one here because there’s one for the other side also centers the rotor into this plate and then this sleeve is centered into this plate so we’ve now centered the rotor on this side of the stator so now we need to go to the other side to put additional tools in to get it centered and then pull it up and out okay at this point if I had the transaxle mounted in that special rotating holding fixture I would just simply rotate it on its side and get the get the rest of the tools hooked up but I don’t I’m not able to use that so I’m just going to put some extra long bolts in this side of the case to hold the case up off of this tool when I tip it over to support it as we pull the rotor out okay so here we go we’re going to tip the tip the whole thing up on its hand just like that so now we’ve got clearance for the tool underneath and we can get the upper tools set up to pull the rotor up and out all right while we’ve got the transaxle tipped on its side let’s take this oil sump cover off and show you what’s inside of there so it’s just a big empty trough and you can see has one two three four five six holes in it where fluid is going to go out and drip down on other parts inside of the transaxle for stator cooling and for the ball bearing lubrication the cover itself has that same aluminum gasket that’s not reusable also while we have this transaxle on its end let’s turn it over and take the coolant sump off next okay here’s our coolant sump you can see this pipe right here is where the coolant comes in and it has to wind back and forth back and forth and then come back out over here the coolant sump which is visible from the bottom of the car with the under car cover removed also has that same aluminum gasket that’s not not reusable why are they not reusable I don’t know maybe the aluminum crushes these I’m going to see if I can buy replacement gaskets at the local Chevrolet dealer it seems like I saw a service bulletin saying that all these parts are serviceable now and it gave the part numbers for them but if not none of these are damaged it only has 35 miles on it and I’ll reuse them and see what happens okay so coolant sump oil sump so now we are ready to pull out the rotor assembly so to pull out the rotor assembly we have a guide pin it’s going to come in and screw into that dowel they had a threaded end on it all right so this threaded guide pin did not line up exactly perfect with the guide pin down below I can’t tell if we’re just spinning the whole thing there we go all right it’s screwed all the way into

that alignment dowel from below now we have this tool that has three holes that go over the holes where the stator bolts are so we need to remove the stator bolts next these stator bolts are not reusable three stator bolts so we put this tool over the top of that we want to be very careful that we don’t damage pry lean or set anything on the stator windings here that could cause damage to them so we’ll get that lined up just like that now I’m going to reposition the camera so you can see how tall this next tool is that fits on here all right we have two clamshell type tools that are going to come in and clamp down over the resolver cam rotor there and this bearing they’re gonna go just like that except I need to split them apart so I can get the next tool in it says this big tall piece right here that’s going to go over and down into our stator bolt holes so we’ve got this threaded shaft we’ve got this adapter right here that these little clamshell tools are going to hook into and then the threaded shaft with a nut on the top of it we’re going to tighten that nut and pull the rotor up out okay so the tricky part of giving this hooked up is getting both of these clamshell tools over this lip right here so I have to loosen the nut on the top and let it come down let me turn this you can see what’s going on there we go okay so we slide that open clamp the clamshells around it put this sleeve over the top of it to lock the clamshell in place snug up this nut to hold the lock in place and then from the top here we start to pull up on the rotor itself I’m going to get repositioned bring my chair up a little higher here so I can reach that nut it takes quite a bit of turning to pull that out okay here we go thirty millimeter wrench we want to turn the nut and prevent the shaft from turning so I’m just going to hang on down here as it comes up those guide pins the guide dowels keep it from rubbing on the stator frame although although there’s almost a strange ratcheting sound as I’m pulling this out that makes me think it’s barely contacting the the stator laminations or the rotor laminations anyway we’ll pull it out and take a look see if we can see any witness marks you can see the top of the rotor now is starting to appear I think we’re finally clearing the top of the yes we are it all of a sudden got real easy to turn the nut so we no longer have the magnet pulling out or

resisting us pulling out okay you can see the entire length of the rotor here get another bearing down below it and a gear below that now we’re supposed to just lift up on this and and pull it out I’m not sure if I’m strong enough I may have to bring in the the engine hoist to pull it out of here but it’s just sitting on these three non-magnetic aluminum poles here and we’ve got the weight of the the rotor assembly itself I measured it earlier but I can’t remember what it is at this moment but let’s see if we can lift this up and out though I cannot so let me get the engine hoist we have to lift it up high enough to clear that alignment dowel so I’ve got to lift it up probably four more inches 100 millimeters or so okay I’ve never tried this before it’s just a lift strap let’s bring it up okay the lifting or the tool was getting stuck in one of the holes for the the stator bolts there we go okay here we go and we’ve cleared the alignment dowel so slide the case out of the way here and we’ll let that back down oh let’s see how much that weighs it says it weighs 60 pounds with the tool the tools probably 10 pounds of that okay we have to remember that this rotor is highly magnetic very strong eight pole magnetic field around this thing and so we need to keep it away from anything any metal particles or any tools or anything else that could cost cause it to receive damage on its laminations here in looking at the the laminations from removing it I don’t see any obvious damage at all there let’s let this down and take the the tool off and just look at the rotor itself little clamshell pieces out of there these tools are magnet earth iron some some sorts so we got to keep those away from the magnetic field as you can see these blue bars are aluminum they’re not sticking to the the rotor itself and then plastic of course works great with the magnetic fields so now we’ve just got our rotor we’ve got our drive gear down here I’ve got a ball bearing and another ball bearing there’s another shim down inside the case a bigger diameter shim for this bigger diameter bearing all right I’m going to get some wooden blocks to put this in all right here’s the rotor for the bolt evie as you can see this bearing seems to have some sort of a gray coating on the outer race where this one does not and on the counter gear bearings they also have this gray coating it doesn’t say anything about what that gray coating is for I suspect it’s to prevent corrosion from the dissimilar metals with possible induced currents going

through them with the the motor running vehicle going down the road I’ve seen this type of coating on universal joints in universal joint caps universal joint caps bearing caps in an aluminum driveshaft the same color I don’t know if it’s the same material but if any of you know what this coating is for if you’d please put that in the comments below I’d appreciate that I’m just speculating okay so we’ve got the rotor out of the way this is a serviceable piece now the last piece to remove is the stator assembly itself and it has three special guide pins that go into the stator bolt holes and screw into the transaxle case and then they’re tapered on the top here and that’s to allow you to slide the stator out without it binding inside so I’ll slide that over there rotate it down and just pull out slightly here it comes just like that so here’s the stator for the Chevrolet bolt Eevee if we zoom in close and look at the stator windings you can actually see there are 1 2 3 rows of these hairpin conductors which means they are 6 conductors deep in this stator and from what I read in the SAE document on this new improved motor that helps reduce the AC power losses at the higher motor rpm a typical stator like in the previous Chevrolet Volt had 2 rows instead of 3 so they were four conductors deep in the Chevrolet Volts and six conductors deep here and one of the people that was on the original design team for the Chevrolet Volt told me that when they designed this electric motor and it’s designed for maximum efficiency and hand power that there was no other motor out there that could even match the efficiency of this motor and they said that they designed this motor to be the next small-block Chevrolet so to say of power trains so the small-block Chevrolet was and still is a very popular very powerful v8 engine and has been for many many years and their intent was to have this motor design maybe even this drive unit be in multiple platforms with the same high power high efficiency motor system if we look at the other side here of the stator windings you can see the the other end of the hairpin conductors and then there’s a drip channel right here for oil to come out of that oil sump and to drip down and go down and lubricate the stator windings because these get really hot this is the heat source inside of the transmission and it and although it gets hot it doesn’t get as hot as the fluid although the fluid gets hot it doesn’t get hot as a normal planetary gearset style automatic transmission and the cooling system surge tank reservoir cap was only pressurized to 5 psi for this loop of the cooling system so much lower amounts of heat compared to an internal combustion engine with a torque converter heat generating planetary gearset style of automatic transmission now just a couple of things to get wrapped up with this disassembly video because we will reassemble it showing the special measurements for the shims and everything when we go back together but one thing I wanted to show you about these electric vehicles is how simple

they are and when I mean when I say simple I don’t mean simple design meaning it was easy to design these simplicity is not necessarily easy but if we look at the number of rotating parts in this entire drive unit there are basically three main rotating parts we’ve got the rotor assembly that then turns the counter gear right here that then turns the final drive three pieces no clutch packs no bands and no sprags no roller clutches no Pistons none of those hundreds of parts that you would see in a typical automatic transmission let alone the internal combustion engine that this is replacing of course there are three main moving parts these pieces here but each one has two bearings on it so there’s six more pieces so there’s nine total and then inside of the differential here we have two side gears and two differential pinion gears so that makes for a total of 13 possible moving parts inside the of this drive unit and only when you’re turning corners would the side gears in the differentials be rotating at a different speed than the differential case so a real basic very reliable system these electric vehicles and and this one is is very efficient and that the design is very compact to where this left-hand output shaft remember goes right through the center of the rotor instead of being offset like on the the Nissan Leaf and other electric vehicles out there so congratulations to Chevrolet and the design team that came up with this amazing and efficient and simplistic evie drive unit and I think it’s absolutely beautiful so coming up I hope to shoot a reassembly video with all the measurements for this drive unit and then we’ve got all of these parts out the drive unit all of the electronics and our and our Chevy bolt back here on the hoist is totally empty yeah under the under the hood so we’ve got to put that all back together and and make it work again even the battery is out the whole thing is stripped as far as the powertrain is concerned and we’re gonna put that back together and and make it work and hopefully get it converted to a DC fast charge thank you for watching