this is a demonstration and discussion
of the operation a rear-wheel-drive manual transmission. The information in
this video is applicable to just about any rear-wheel drive manual transmission, although this particular one is a 1992 Toyota Truck five-speed manual transmission,
the the R-150E, it really doesn't matter
because we could be looking at a brand new rear-wheel drive transmission, from just about any manufacturer, and
they will have the same basic components in them. So this video is
intended to give you the theory of operation, not so much what's unique to each manufacture, so to begin with, over here we have the input shaft that your clutch disk is going to connect to, and that's going to give us power from the
engine. Underneath here we have the countershaft, and since it is geared directly to the input shaft,
it's going to turn anytime the input shaft turns. But notice the output shaft back here that goes
to the rear wheels, isn't turning it all the when I turn the
input shaft, and that's because we are in neutral.
now if I zoom in a little bit here you can see that we have four different shifts
shafts here and the shift mechanism that sticks
through floor board going to come down and connect and operate these shift shafts. so the top shift shaft is the 3-4 sure shaft, it connects to the
3-4 shift fork right here to give us fourth gear or
neutral or 3rd gear. The next one down is the 1-2 shift shaft, and it connects to the
1-2 shift fork so we can have 2nd gear or 1st-gear right here We have the reverse shift shaft, so it connects to a shift
fork down below, that moves the reverse idler into
contact with the counter gear and drives the output shaft backwards.
and then we have a 5th gear shift shaft for 5th gear right back here in the back of the
transmission. This could be a 4-speed if we didn't have the 5th gear shift shaft, this could be a 6-speed and if in the back to the
transmission we had two gears instead of just one. 7-speed, 8-speed, it doesn't matter they all have shift forks, some sort of
shift shaft mechanism, and they all have an input shaft, at least one counter shaft, some of the heavier trucks have two counter shafts and then an output shaft. I am going to rotate this transmission around and zoom back out, let's just look at the front here for a
moment, you can see the input shaft right here,
we have some splines, we have a little machined area right
there, those splines are where our clutch disc is going to come in it has splines if its own and damper Springs, and so it's going to
slide on to those splines, and when the clutch is
applied, it will turn the input shaft of the transmission. Also in the front here on
this machine area we have a pilot bearing it's going to fit right here, and that fits
into the back at the engine's crankshaft, and when ever you change the clutch or the
transmission, you should install a new pilot bearing there also. so let me continue rotating transmission
around to where we've got the back of the
transmission, the output shaft over here, the front with our clutch disk and our input shaft over here, and now if we zoom in we can look at the synchronizer assemblies, because manual transmissions - in order to shift
from one gear to the next, when all of these gears are spinning at
different speeds, so in order to complete a shift from first gear into second, second to
third, third to fourth, fourh to fifth and so on, we have to synchronize the
speed of those gears, which means the speed of the input shaft
and whatever gears it happens to be turning needs to be synchronized to the speed of
the output shaft, and so that's done with synchronizer assembles. and so right here is our 3-4 shift fork, here is our 1-2 shift fork
back here and we have a shift sleeve and then right down here you can see
this little brass blocker ring, sometimes is called a
synchronizer ring the synchronizer typically is a brass ring, it actually has a tapered edge on the inside in other words it's not perpendicular, it is on an angle like this and that's going to ride up against a gear that also has a tapered cone, and the
synchronizer sleeve is going to push that tapered
cone of the brass ring of the synchronizer up into the cone of the gear itself, this shiny surface
right here. so we've got a tapered area here on the synchronizer, we've got a tapered
area here on the gear itself and the
synchronizer will be turning the speed the output shaft the gear will be turning the speed of the input shaft when you step on your clutch and we quit delivering power from the engine, we want
to synchronize the speed of those two to make them be the same, and so this
synchronizer sleeve right here will push onto the brass synchronizer
ring and shove it onto the gear that's turning
a different speed than the synchronizer hub and it will either slow it down or speed it up to where it would match the speed of the input shaft to the output shaft and
so let me give you the little better
demonstration, a different demonstration of that, let me zoom out just a little bit, I'm going to grab the output shaft right
here am going to grab input shaft where the
clutch connects and notice when I spin the output shaft, and let me zoom in so we can see what's moving here I'm just going to spin the output shaft
the input shaft not going to move notice the only thing spinning is the 1-2 synchronizer sleeve and the 3-4 synchronizer sleeve the 1-2 synchronize sleeve also happens
to be the reverse gear that we slide the idler into down here to get reverse but those two synchronize sleeves spin the same speed, and notice 5th gear does back here also, the fifth gear
synchronizer sleeve watch this back here, they all spin with the output shaft. Now I'm going to hold the output shaft still and turn the input shaft notice now everything else in the
transmission rotates except for the synchronizer sleeves so to shift from one gear to the other somehow we have to connect those two
shafts together and once again it's done with
synchronizers so let me zoom out just a little bit
here and just going to take you through the
different gear ratios of the transmission and show you the shift sleeves and synchronizers moving, and so on the output shaft here I have a yellow label that says output
shaft on the input shaft right here have a
yellow label that reads input shaft and so I'm going to a shift this into first-gear now typically when you shift into
first gear the vehicle is stopped the engine is running typically, but if your clutch pedal is
pressed that releases the clutch disc and
disconnects it from the flywheel which is bolted to the engine's crankshaft and so the input shaft will stop and so here's our 1-2 synchronizer, right here the shift fork that comes and grabs the
synchronizer is just, we're just going to push it back to
the first gear position, maybe okay, I just shifted in the first gear by moving the
synchronizer sleeve back with the shift fork I've got the input
shaft label the output shaft label for this
particular transmission we should have a gear ratio of 3.83 to 1, (3.83:1) so that means I should turn the
engine with the clutch, input shaft, 3.8 times, so
there's 1, 2, 3, and 3.8 times to get one turn the output shaft back here, so that, that is our first gear, alright now to go to second gear we need to move
the synchronizer sleeve and disconnect the synchronizer hub from the first speed gear your and move it
over here to connect it to the second speed gear but while it shifted into the first speed gear, let me zoom in a little bit more
you can see a little better detail, we've got the synchronizer
sleeve, the synchronizer hub right below it, the brass
blocker ring right here and the gear, second speed gear
its self and so brass blocker ring, just like the
piece I showed you with the tapered cup, this gear right here is going to have, this is in the exact
year but it's it's just like it, it's going to have this tapered edge,
and so when we shift into second-gear this sleeve is going to come
over push against the brass block a ring and try to lock it to the same speed as the synchronizer sleeve which is
connected to the output shaft which with your foot on the clutch pedal,
because remember you have to have your foot on the clutch to shift that should allow the two shafts, the input shaft and the output shaft to connect together and shift into second-gear so we will pull that forward into second gear, there we go, now we're in 2nd gear the output shaft is connected to the input shaft but let me line up our stickers here, here's our
output shaft label let me zoom out so you can see it here's our output shaft label here, here is our input shaft with our gear, our shifter sleeve, moved
into the second gear position we should have a gear ratio of pretty much
to 2 to 1 (2:1) 2.062 to 1, so here we go there is one turn the input, two turns of the
input, and a tiny bit more 2.06 turns to 1 and all we did was connect to the output shaft through
our shift sleeve and hub to the second speed gear through the synchronize rings okay, now we're going to shift out of second-gear and here's our 3-4 shift sleeve and shift fork, so we are going to move to the 3rd gear position so let me shift that to third gear there we go, we moved back to the third gear position and now our gear ratio should be 1.4 to 1 (1.4:1) so here's one turn the input and about four-tenths of a turn of the input
and we get one turn of the output so 1.4 turns of the engine to 1 turn the
output shaft which goes to the rear
driveshaft and the rear axle to propel the vehicle. notice here for the
3-4 shifter, we have got the synchronizer sleeve, the synchronizer hub down below it, the brass blocker ring or synchronizer and the 4th speed gear right here these synchronizes, by the way, the material the brass, bronze alloy material there does wear out over time, there's a bunch
a little grooves there, I hope you can see it is this video, those grooves wear out and it gets the to where the synchronizer has a hard
time synchronizing the speed the input shaft to the output shaft, when
that happens, if you keep pushing on the shifter you can end
up with a grinding noise so, it grinds while you step on the clutch and try to shift. So when
you disassemble a transmission one of the checks you can do is to take a
feeler gauge setup, just take a feeler gauge, and there is, with everything assembled
properly, there is a minimum gap that's allowed between the brass
synchronizer blocker ring and the gear itself. If this synchronizer
ring is worn really bad that gap is going to be extra small
because it'll go farther up on that tapeed cone of the gear. If it's in good shape then
you will have a a bigger gap in there, so lot a vehicle
manufacturers have a specification for that gap for you to
measure also I've seen some of these that just
crack the grooves have not worn out of it, but
it's got a crack and so the whole thing just spreads instead of pushing and synchronizing
the speed of the gears so there we are in 3rd gear, we want to
move to 4th gear, so fourth gear is this gear right here, let me
zoom out just a little bit to show you the physical size of the gears first gear is giant gear right back
here and we have that gear ratio of 3.8 to 1 second gear is this gear, it is a little bit
smaller with a gear ratio of pretty much 2 to 1, 2.06 . third gear right here is even smaller than
second gear; 1.436 to 1 fourth gear on this particular
transmission is a 1 to 1 gear ratio so what's going to happen here is when we
move the gear selector into fourth gear, right there move our shifter sleeve up and in, we are going to have one turn of the input shaft, so here's our label, let me zoom out a little bit you can
see here our input shaft label just starting to
show right here, here's our output shaft label in full view, but notice now we have one turn i equals 1 turn out, that is a 1 to 1 (1:1) gear ratio, also called direct drive some transmissions its fourth gear, some
it is fifth, some its third, it just depends, some don't
even have a direct drive, it is just something a little higher than 1 to 1 or
lower than a 1 to 1 gear ratio so, that his direct drive, but this is a five-speed
transmission that has overdrive, so if we shift back into neutral on the shifter here we are in neutral, there's no connection
to the output shaft, now on the back over here we've got a
5th gear with its own brass blocker ring and
shifter and shift fork and if we move it into the fifth gear position here we go, now we are in overdrive where we should turn the input shaft just eight-tenths of a turn to get one turn of the output shaft, so here's our label back
here and I am going to just hang on to the the clutch
housing here, notice as a turn the
clutch not the housing, the clutch disc itself,
we are going to get a full turn the output shaft before I can bring my fingers all we
back around to one full turn here so we are in overdrive, you get a full turm the output shaft, but I'm still two-tenths of a turn away from a full turn
on the input shaft that's overdrive which gets us better fuel
economy on a six-speed transmission, some six
speeds fifth gear is the direct-drive, the 1 to 1 gear
ratio but anymore because of the fuel economy
regulations fifth gear, like on this transmission is
overdrive and then sixth here is a double
overdrive so you may have and instead of the
0.8 to 1 gear ratio that we have here fifth gear you might have a 0.6
or I have even seen as low as a 0.5 to 1 gear ratio like on a Viper or a Corvette mad for really high vehicle speeds, it also gets you some pretty decent fuel economy but that gives us overdrive, so now lets take it out of fifth gear, go back to neutral so here we are in neutral again, now we
want to go to reverse notice right here in the front we've got
a reverse idler gear that's not doing anything so when we move to reverse we're going to
move this idler gear over in its going to mesh with the 1-2
synchronize sleeve and the counter shaft at the same time there we go, so we move that over with its own little shift fork, reversed does
not have a brass blocker there's no synchronization of reverse, so
for reverse you need to be stopped to shift into reverse or it will grind so now, when we turn the input shaft clockwise as viewed from the front here,
notice the output shaft is turning the opposite direction so lets see what the reverse gear ratio might be, there is one, two, three, four, a little bit more, about 4.1 to 1 gear ratio in reverse let me take it back out of reverse and go
right back to neutral. These manual transmissions
have bearings they can go bad, they have some end play
checks, there's selective shims that are designed to hold everything in the correct position the proper lubrication type and level is
important a lot of manual transmissions and front-wheel drive transaxles, manual transaxles, are using a
special synthetic gear lube now for improved fuel economy so even though this is a 1992 rear-wheel drive transmission, if you
open the 2012 rear-wheel drive transmission you would see the same parts about the only difference you see pretty
much any more is the 1-2 synchronizer instead of having
just a single cone the 1-2 synchronizer like this it will have a dual cone or even a
triple cone synchronizer which allows for
high-speed performance type shifts from 1st to 2nd
gear or from third back down in the second
but on every single shift, you have to go to
neutral between the shifts I was looking at 2010 rear-wheel
drive transmission that we've got here and it's this exact
same model or looks just like this except this
housing, instead of being cast iron, is is aluminum so they are making it lighter
weight to save on fuel economy. This has been a demonstration of the
operation of a rear-wheel drive manual transaxle, or, transmission, I'm sorry, the
rear-wheel-drive transaxle, sorry, front-wheel drive transaxle, operates just like it except instead of
having the output shaft sticking straight out the
back think of on a transactional as this
output shaft being cut off turned back around and headed around frontwards here to where you can drive the final drive
unit of the front-wheel drive, but it still has the same gears same type of synchronizers, the same precautions during service as well. Probably the most difficult thing
working on these transmissions is you it requires a lot of hydraulic
press work, and you have got to be real careful as you are pressing these gears on and off that you don't break the gears or
break any of the parts, because they are very expensive
Just when you think he's cleared his throat for the last time, he hits you again.
This video does a good job showing a manual transmission using an actual transmission itself. Good overview of how synchros work as well.
I so very badly wanted to watch this video. I am VERY interested in how a manual transmission works. This fucking guy though...he single-handedly killed my enthusiasm. I'm just going to stare at a wall for a while now.
The magic voodoo box is less magical now.
His voice reminded me a little of Ron Swanson. Although I now understand how selecting gears works better now.
Man sweet video. I have to come back here and watch when im less tired.
Does that guy have a manicure? He has some beautiful nails for being a mechanic.
Great video, explanation, and demo. Coming from an engineering student, this guy is SUCH an engineer.