Torque Converter explanation?

[rogcontact]

Could someone please give me details on exactly how a torque converter works, or a link to one?

Does it have different levels of how much torque conversion happens? Can it loosen or tighten? etc...

[franka]

Could someone please give me details on exactly how a torque converter works, or a link to one?

Does it have different levels of how much torque conversion happens? Can it loosen or tighten? etc...

Yes.

Try google.

Basically there are two fan wheels face to face in a fluid. When one fan turns it drags the oil with it which makes the other turn. There is no solid connection between them.

Lots of the fan details and space between can be changed to get all sorts of different responses.

[NNY528I]

Most torque converters have only one mode,(ie they are not adjustable) However by the nature of the design, as the rpms of the shell increase the amount of torque transfered also increases up to the point know as the stall speed at which maximum torque transfer occurs(the point at which maximum rotor speed is obtained and the shell and rotor match speed) Throughout the RPM range there is a certain amount of energy lost to heat and friction due to turbulence in the fluid, to offset this most transmissions are equipped with a Locking torque converter, this is a misnomer at what actually happens is that a clutch between the input shaft and the shell engages and physically locks the two pieces of the converter together allowing for direct driving of the transmission with no hydralic enegy loss.

Converters are available in a variety of different stall speeds to suite the needs of the engine, power, use etc. High stall coverters are used in drag racing applications where as many cars use a lower stall speed to allow for better economy. I do not know if such converters are available for BMWs.

Most transmissions(ours especially so) have an adaptable shifting pattern to tune the gearing, rpms etc to the driving conditions. These things do not impact or adjust the TC operation only how the TC output is used. The action of the Torque Converter clutch can sometimes be felt as a hesitation, vibration or pause when jumping ont he throttle or when coming to a sudden stop. You can also notice it by jumps in the RPMs while driving on the highway(small 500rpm, drop while cruising or 500rpm rise while accelerating, also many times the brake pedal will automatically disengage the clutch, when climbing hills this can also be seen depending on the amount of throttle that is applied)

There is a lot of info online as well.

Do you have a specific problem that is occurring prompting you to ask the question?

[franka]

You can get a variety of street to racing torque converters for BMWs from folks like TCI or B&M, etc.

[00BMW540i6]

http://auto.howstuffworks.com/torque-converter.htm

[rogcontact]

Most torque converters have only one mode,(ie they are not adjustable) However by the nature of the design, as the rpms of the shell increase the amount of torque transfered also increases up to the point know as the stall speed at which maximum torque transfer occurs(the point at which maximum rotor speed is obtained and the shell and rotor match speed) Throughout the RPM range there is a certain amount of energy lost to heat and friction due to turbulence in the fluid, to offset this most transmissions are equipped with a Locking torque converter, this is a misnomer at what actually happens is that a clutch between the input shaft and the shell engages and physically locks the two pieces of the converter together allowing for direct driving of the transmission with no hydralic enegy loss.

Converters are available in a variety of different stall speeds to suite the needs of the engine, power, use etc. High stall coverters are used in drag racing applications where as many cars use a lower stall speed to allow for better economy. I do not know if such converters are available for BMWs.

Most transmissions(ours especially so) have an adaptable shifting pattern to tune the gearing, rpms etc to the driving conditions. These things do not impact or adjust the TC operation only how the TC output is used. The action of the Torque Converter clutch can sometimes be felt as a hesitation, vibration or pause when jumping ont he throttle or when coming to a sudden stop. You can also notice it by jumps in the RPMs while driving on the highway(small 500rpm, drop while cruising or 500rpm rise while accelerating, also many times the brake pedal will automatically disengage the clutch, when climbing hills this can also be seen depending on the amount of throttle that is applied)

There is a lot of info online as well.

Do you have a specific problem that is occurring prompting you to ask the question?




most transmissions are equipped with a Locking torque converter

Do our e39's have this locking torque converter? If so, does releasing the throttle pedal free this lock and do you notice your car locking in the torque converter on the 3-4th gear?

[rogcontact]

http://auto.howstuffworks.com/torque-converter.htm


Awsome link... Does anyone really understand exactly what they are talking about when they say that there is a change at around 40MPH?

[franka]

Awsome link... Does anyone really understand exactly what they are talking about when they say that there is a change at around 40MPH?

The finned units start to match speed.

[rogcontact]

well then... that explains it

[NNY528I]

most transmissions are equipped with a Locking torque converter

Do our e39's have this locking torque converter? If so, does releasing the throttle pedal free this lock and do you notice your car locking in the torque converter on the 3-4th gear?

Yes

[franka]

The 40 mph thing actually is explained right in the article.....

Something a little bit tricky happens when the car gets moving. There is a point, around 40 mph (64 kph), at which both the pump and the turbine are spinning at almost the same speed (the pump always spins slightly faster). At this point, the fluid returns from the turbine, entering the pump already moving in the same direction as the pump, so the stator is not needed.

[rogcontact]

I think I basically understand it... Question now is, can you notice these changes while driving your car? Is this the reason why my car up shift to a much lower rpm going into the 4th gear? Because by then the Turbine and the Pump are going close to the same speed and lower rpm's are needed to maintain\accelerate that speed?