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