Ok all you tranny techs, i got a good one for ya. I recently traded some parts to get an HD Tranny upgrade. comes with the axle, diff, and even an input shaft....just gotta find a cover for it.

My question is, could somebody walk me through exactly how a transmission for our cars is setup? what part connect with other parts, how the torque converter works, different things like that. start with foot on the gas and go from there. im trying to figure out what i'd need.

does the differential connect to the input shaft? im just trying to connect all the pieces lol.

thanks!

maybe we could make it a sticky if the writeup is good enough??

 

tripleedgeperformance.com

that dude will talk to you about Transmissions.

 

i've talked to him before, but seeing as im not planning on buying a new tranny from him, i didnt really wanna waste his time. just hoping for a good writeup on what and how parts connect to each other in the drivetrain.

 

I really don't think he'd mind the conversation haha

wish I could help you a little further.

 

Its been awhile since I've had the tranny apart- so I'm a little fuzzy on some stuff, but here is the general idea:

Obviously your crankshaft spins from combustion- at the back of the crankshaft, your flexplate bolts to it with a small diameter bolt pattern (the outside rim of the flexplate has the teeth that your starter spins to start your car), the torque converter bolts to the flexplate with 3 bolts far away towards the edge of the flexplate. The flexplate and torque converter are housed in that big bubble part of the trans right behind the engine.

The torque converter slides onto the input shaft of the transmission which transmits power to a sprocket. There is another sprocket down in line with the long tailshaft of the transmission- and these two sprockets are connected via a chain (it works just like a bicycle- your power output and drive axle are connected via a chain and a couple of sprockets). So the power comes through the torque converter, into the input shaft which is connected to a sprocket which spins a chain which spins another sprocket down by the tailshaft of the transmission (roughly in line with the wheels).

From here, that lower sprocket connects to the big stack of clutches and bands for the various gears that extends most of the way through that tailshaft. At the end of this is a small shaft called the sun gear shaft which spins the final drive internal gear and the differential at the end of it. Out of the differential come your two axles- your passenger side axle is driven right off this end of the differential. However, your drivers side axle is all the way on the other side of the car- so to get power over there, a long output shaft connects in the drivers side of the differential and goes all the way through the transmission and transmits power to the drivers side axle. Obviously this means that everything in that long 'tail' of the transmission is hollow to allow for the output shaft to connect the differential to the drivers side axle.

Thinking about it in simpler terms like a RWD setup- your differential or "rear end" has a driveshaft come in the front, and one axle comes out of each side of it. This is the same idea with our differential- except we have a hollow final drive sun gear shaft instead of a driveshaft that spins the differential, and instead of 2 axles coming out, you have 1 axle and 1 output shaft to connect to the other axle.


So here is the general flow:
engine crankshaft > flexplate > torque converter > input shaft > sprocket > drive chain > sprocket > clutch/band gear assembly > final drive sun gear shaft > differential > axles (1 axle, 1 output shaft connecting to the other axle) > wheels

Its a bit more complicated than that, but thats the general idea. Here is a nice site about the diff:

http://www.thrashercharged.com/tech_...ferential.shtm


Also, the reason you can pull up to a stoplight and not kill the engine is because the engine in an automatic transmission isn't mechanically connected. The torque converter connects the flexplate/crankshaft to the transmission input shaft via basically two fan blades immersed in transmission fluid. As you hit the gas, the fan connected to the crankshaft starts to spin very fast, thus spinning the fluid as well- which causes the fan hooked to the transmission's input shaft to spin- and the car to move. However, when you come to a stop, your brakes are enough to hold the car from moving as the input fan from the engine is spinning slowly at idle. Obviously power transmission between these two "fans" is never perfect, you will always have an RPM difference between the two, and that is why most modern torque converters have a lockup clutch. This basically hooks the input and output of the torque converter together directly with a clutch to eliminate slipping (ever notice how when taking off, the car seems to shift/drop RPM 4 times even though there should only be 3 shifts for a 4 speed?)- the extra RPM drop is from the torque converter "locking up" and forcing your engine speed to exactly match your transmission speed. Without this, you would always be wasting extra gas to compensate for the losses.


I know my description isn't very clear- more images would be helpful- but hopefully you get the idea. Maybe someone can find a link to a teardown of a 4t65 somewhere that has all the stuff labelled.

 

wow.


as always bumpin', im in awe of what you know.

thanks!