Automatic Transmission Questions?

Question

I got a few questions that I have been wondering about when it comes to auto transmissions:
Why can't you feel them downshift when you slow down or come to a stop, and why wouldn't it automatically downshift when your slowing down to help you slow the vehicle??? I do that in a manual all the time and it is one of the reasons why I hate automatics. Being an automatic you would think that this would just be another thing that it should do automatically.

Answer 1

Below is a basic explanation for what you asked.

An automatic transmission is driven by the engine through a component called a torque converter. While the engine is applying power to the converter, the converter provides hydraulic pressure to the transmission for the clutches of the different gears and the speed of the driveshaft dictates which gear the transmission should be in. As long as there is pressure from either the engine or transmission, then the engine and transmission are somewhat locked together. When you release the gas on an automatic, the engine slows down and the pressure drops in the converter releasing the transmission lock. It is designed to do this so that the car does not automatically slow down just because the engine slowed down. It is very much like when you push in the clutch on a stick shift when you wish to coast, only the automatic does it automatically.

Now, that being said, this only occurs when the transmission is in drive. If you wish to use the transmission more like a manual transmission to slow the car down, simply move the gear shift into a lower gear and this will force the transmission to lock into a lower gear and provide that pressure I talked about earlier, just in reverse from the transmission to the engine, to engage the lock between the engine and transmission and slow the car down. The transmission will automatically downshift into lower gears as the cars slows down to within the limits of that gear so as not to blow out the transmission with RPM's that are too high for the gear based on the speed of the car. When in drive, the transmission will automatically lock back into the proper gear you need when you push on the gas again based on the speed of the car, just like you shift into the appropriate gear necessary for the stick shift depending on your speed and your judgement, just that the automatic does it automatically for you.

Below are some links that may help also.

Hope that helps.

Answer 2

on older trannys shifting is controled by govenor fluid pressure and shift valves in the valve body, as the output shaft spin, it turns the governor, as it turns it creates higher fluid pressures, which moves the valves against spring pressure, which directs tranny pump pressure to differanant clutch packs.

the reason the tranny doesn't solw the vehicle down when slowing/stopping is due to the torque converter. it is an automatic clutch, when engine speed falls below input shaft speed, the torque converter will freespin. this is the reason you don't feel the downshift, it happens, the converter hides it.

on newer trannys the converter is still the same, but shifting is done electronically with shift soleniods instead of governors and valves.

Answer 3

I consider maximum posts.. many times at idle the transmission oil pump is popping authentic slow and that's not lubing each and every of the aspects that are nevertheless turning... additionally it particularly is a marvel to the transmission once you shift from independent returned to force on an identical time as happening the line and which will actual kill it extra

Answer 4

well the reason you dont feel the downshift is a little valve called a "modulator" which irons out the bumps...secondly...automatic cars dont need to assist the braking in a modern car because braking systems have greately improved over the years and are quite capable of stopping your car.....when you drive a manual(stick shifter) you should always use brakes for slowing and gears for going!.....its cheaper to replace disc pads than gearboxes? eh...

Answer 5

When it slows down it pops it into neutral and waits to feel what gear it should go into next. Vehicles don't think like humans so I don't think it can grasp the concept of down shifting to slow. Hence the reason I hate automatics too.

Answer 6

You are't supposed to feel the downshift - it just does it!!

I hate autos too! Gimme a gearstick every time!

Answer 7

all the automatic tran should b slow down when u press break otherwise u have problem and go to doctor

Answer 8

People buy automatics so they wont feel it.Stick your stick,i mean stick with your stick.