This is a demonstration of the power flow through a General Motors Hydra-Matic 6T70trans axle this
is a 6-speed transaxle that has been used since 2007 in front-wheel drive GM passenger cars
typically with small V-8s or larger V-6 engines there is a 6T75 version of this as it's been
beefed up a little bit more to handle higher input torque and there's a 6T40 and a 6T45 for smaller
four-cylinder engines that is patterned after the same trans axle this trans axle being a six-speed
has three planetary gear sets we have an input gear set a reaction gear set and an output gear
set that are in this inside of all of this with your standard planetary Sun gear planet carrier
with planet gears and ring gears we have three separate Sun gears three separate planet carriers
and three separate ring gears on this transmission so we don't have a Simpson gear set or any other
type of gear set here it's just three simple planetary gear sets in line with each other
there are several clutch packs in this trans axle to be aware of we have a 4-5-6 clutch pack that is
going to spline to this housing that connects to the reaction carrier we have a three five clutch
pack that's inside of this housing that will rotate with the turbine shaft in the input shaft
that took to the torque converter and then we also have a 2-6 clutch that splines to the outside of
the same housing that will stop it from rotating in second and sixth gears we have a Low-R clutch
that will grab these teeth that Low-R clutch is also used in conjunction with this one-way roller
clutch or one-way clutch it's not a roller clutch and it's not a Sprag if you listen carefully it's
actually got a ratchet mechanism to lock it in one direction very much like a ratchet of a tool
set and then we have a 1-2-3-4 clutch pack that will be down here and by the way the 2-6 clutch
the long reverse clutch and the 1-2-3-4 clutches these are all holding clutches they're going to
grab these housings and stop them from rotating in the gears that their name represents and then down
here we have the output foot to the final drive there's a idler gear and then the final drive
gear in this transaxle and then we have an input shaft that goes into the torque converter into
the turbine and this shaft goes all the way down through the center of all of these three planetary
gears and it actually splines to one of those inside and if there's set of splines right here
I think it's the reaction Sun gear if I remember correctly so when our engine turns the torque
converter is going to turn this housing down or the turbine shaft down below that's the same as
turning this upper housing here because they're connected together so what I'd like to do is run
you through the six forward gears and reverse on this trans axle so to get started with we will do
reverse for Reverse we're going to have the 3-5-R clutch come on and this is inside of this housing
so it's going to turn and then we're going to have the Low-R clutch come on and it will hold
this piece from turning and we've got a reverse gear ratio of 2.880 to one so if I hold this
solid and we watch this sticker here I should turn this 3-5-R clutch housing 2.8 eight times
to get one full turn of this output gear so here we go and notice it's turning backwards of the
up the direction I'm turning the 3-5-R clutch there's one two and not quite three 2.880 turns
of the input to one turn of the output alright now let's go to first gear in first gear we're
going to have the 1-2-3-4 clutch apply which is going to hold this housings steady and then
we're also in first year just going to turn the input shaft the spline to the reaction
Sun gear so first gear is very low on this transmission it's actually a 4.484 to 1 gear
ratio extremely low gear ratio so if we watch the input turning here to the output turning whoops,
I’ve got to hold the Low-R clutch also so here we go one turn two turns at the input three turns of
the input four turns of the input and there we are 4.484 so four and a half turns of the input to get
one turn of our output so that's first gear second gear we're going to continue to hold the 1-2-3-4
clutch and now we're going to turn or I'm sorry now we're going to hold also the 2-6 clutch so
I'm going to hold both of these this housing and this housing and turn the input and our second
gear ratio is 2.872 to one so I'm going to hold both of those the best I can and turn the input
well actually let me get the sticker lined up here okay so here we go one input turn to input turns
and not quite three 2.872 input turns to one turn of the output for second year for third gear we'll
continue to hold the 1-2-3-4 clutch housing from turning and now we'll apply the 3-5-R clutch which
is inside of this housing so that means we're going to hold this housing we're going to turn
this housing the same speed as our input shaft and we should get 1.842 turns of the input two
one turn of the output so here we go there's one turn in and about 8/10 of a turn around 1.8 to 1
gear ratio for third gear fourth gear is a gear ratio of 1.41 to one and so now we're going to
have the 4-5-6 clutch apply well the 4-5-6 clutch if you recall is down inside of this housing and
it's going to spline to our input housing so I'm going to simulate that by putting that down in
there and wedging it in place with a paper towel just for this demonstration we'll put that whole
assembly back in here lined up so we were looking at fourth gear with the gear ratio of 1.4 turns
at the input to one turn of the output so we're going to hold the 1-2-3-4 for fourth gear clutch
and turn the four or five six clutch housing with the input and get 11.4 turns so here's
one turn of the input and we've got one turn of the output to 1.4 turns of the input now fifth
year on this trans axle is direct drive and so we're going to have the 4-5-6 clutch apply which
is inside of this this housing we just had that apart we're also going to have the 3-5-R clutch
apply so that means both of these are going to turn the same speed they're locked together so
I'm just simply going to hold these two together and turn it and one turn in equals one turn out
which is our fifth gear direct-drive on this trans axle so this trans axle is not a double overdrive
it's a single overdrive and only in sixth year in sixth gear we've got a gear ratio of 0.7 for
two to one so we're going to still drive the 4-5-6 clutch down inside of this housing but
now we are going to hold the 2-6 clutch housing right here steady so let me get this back around
so we can see our sticker here and so I'm going to hold this solid turn the 4-5-6 clutch and we
should get one full turn of the output to the final drive with only roughly three quarters
of a turn of the input so here we go notice it's turn the output is turning faster than
the input there's one full turn in and we did not get one full turn out we started right over
here so that's the 0.742 to 1 gear ratio in sixth gear so once again this has been a demonstration
of the power flow through a Hydra-Matic which is General Motors 6T70 front-wheel drive transaxle
used in 2007 and above General Motors select - General Motors front-wheel-drive passenger cars