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
There are so few details about the motors in EVs that anything is welcome.
The prof says that one of the members of the design team told the prof that this is intended to be the next, electric, SBC. That's helluva reputation to live up to. I guess we'll see in 50-60 years lol
God it's so funny to me that they have an electrical shifter connected to a mechanical shifter which actuates a lever with an electrical sensor to tell the drive unit if it's supposed to be in gear or park or reverse.
I wonder if this motor is gonna be used in future GM EV vehicles. The Bolt EV is honestly surprisingly fun to drive.
These fixed ratio gearboxes are so nice and simple compared to a modern automatic transmission.
e: is it normal for the front wheel differential to be integrated directly into the transmission?
q: where are all these aluminum gaskets not reusable?
That definitely looks a decently easy. I figured not many movable parts... but even less than I had thought!
I think this could probably be a thirty minute video if the guy talked at a normal rate.
Thanks for posting, very interesting.