5AT Transmission basics....Info
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5AT Transmission basics....Info
I pulled together some of my notes on Torque converters/transmissions for those with the 5AT. Most of this is not Nissan specific, and may not include some of the features we enjoy with the Nissan 5AT, but these are the basics. Enjoy!
"What is stall speed and how do I determine what stall I have now?
Stall speed is a term used to describe the rpm at which the torque converter transfers the power from the engine to the transmission. There are different ways to test stall speed. "Foot brake stall" is when you press the brake pedal and then press the gas pedal. When the car doesn't go anymore or the tires start to spin that is "brake stall". (DO NOT TRY THIS! THIS MEASUREMENT IS MEANINGLESS AND POTENTIALLY DANGEROUS TO YOU AND THE TORQUE CONVERTER!) "Flash stall" is when you, from a dead stop, press the gas pedal to wide open throttle (wot). Watch your tach needle, you will see the needle jump to a certain rpm, that is "flash stall". A drag racing-style trans brake will give you closer to the true stall speed of a torque converter.
What is torque multiplication?
Torque multiplication is a term used to describe the amount of torque the torque converter will multiply. A torque converter is basically a fluid coupling between your engine and transmission. There is no direct mechanical link until the torque converter is in lockup mode. The pump assembly of the torque converter is directly linked to the crankshaft of the engine, however the turbine assembly of the torque converter is not. It is connected to the transmission input shaft. When the oil is pumped to move the turbine it is actually pushing the turbine at a higher rate. Each torque converter pump and design pushes the fluid differently, therefore giving you different rates of turbine speed . All of this only means that different torque converters will give you different torque multiplication rates simply by design.
What does torque converter efficiency mean?
Once the torque converter does it's job multiplying torque for take off, the function of the torque converter is to be a link (sometimes called a fluid coupling)from the engine to the transmission. Keeping in mind that the pump assembly and the turbine assembly spin at different speeds, every torque converter has a different rate of slippage between the two. The amount of slippage is what determines efficiency. This is why auto manufacturers created lockup torque converters. Rather than having a torque converter that is let's say 92% efficient, they mechanically link the engine to the transmission, giving it a 1:1 ratio or creating 100% efficiency. This lowers the rpm of the engine, therefore increasing fuel efficiency.
Why do I need a higher stall speed converter?
Theoretically, for maximum acceleration the stall speed of the torque converter should match the peak torque rpm of the engine. A good explanation for the way it works is this: when you go outside jogging you start to breathe in and out faster and harder. Well the same thing goes for a performance engine. The engine is breathing in and out harder and faster, at a higher rpm. If a high performance engine makes power at a higher rpm, then a higher stall speed torque converter is what you need to put more power to the ground quicker.
Are there any other upgrades that I should consider when installing a new torque converter?
You might want to consider a performance tire upgrade such as a "drag radial" tire. Traction will be your biggest problem..... By putting power to the wheels, at a higher rpm, you begin to realize that a suspension upgrade might be a necessary upgrade as well. The only other recommendation is, depending on the application, some performance torque converters create more heat and long term heat kills transmission life. A light bulb that burns twice as bright burns half as long. ... Tests have shown that coolers can increase your cooling capacity by 100%. "
Protorque....
"What is stall speed and how do I determine what stall I have now?
Stall speed is a term used to describe the rpm at which the torque converter transfers the power from the engine to the transmission. There are different ways to test stall speed. "Foot brake stall" is when you press the brake pedal and then press the gas pedal. When the car doesn't go anymore or the tires start to spin that is "brake stall". (DO NOT TRY THIS! THIS MEASUREMENT IS MEANINGLESS AND POTENTIALLY DANGEROUS TO YOU AND THE TORQUE CONVERTER!) "Flash stall" is when you, from a dead stop, press the gas pedal to wide open throttle (wot). Watch your tach needle, you will see the needle jump to a certain rpm, that is "flash stall". A drag racing-style trans brake will give you closer to the true stall speed of a torque converter.
What is torque multiplication?
Torque multiplication is a term used to describe the amount of torque the torque converter will multiply. A torque converter is basically a fluid coupling between your engine and transmission. There is no direct mechanical link until the torque converter is in lockup mode. The pump assembly of the torque converter is directly linked to the crankshaft of the engine, however the turbine assembly of the torque converter is not. It is connected to the transmission input shaft. When the oil is pumped to move the turbine it is actually pushing the turbine at a higher rate. Each torque converter pump and design pushes the fluid differently, therefore giving you different rates of turbine speed . All of this only means that different torque converters will give you different torque multiplication rates simply by design.
What does torque converter efficiency mean?
Once the torque converter does it's job multiplying torque for take off, the function of the torque converter is to be a link (sometimes called a fluid coupling)from the engine to the transmission. Keeping in mind that the pump assembly and the turbine assembly spin at different speeds, every torque converter has a different rate of slippage between the two. The amount of slippage is what determines efficiency. This is why auto manufacturers created lockup torque converters. Rather than having a torque converter that is let's say 92% efficient, they mechanically link the engine to the transmission, giving it a 1:1 ratio or creating 100% efficiency. This lowers the rpm of the engine, therefore increasing fuel efficiency.
Why do I need a higher stall speed converter?
Theoretically, for maximum acceleration the stall speed of the torque converter should match the peak torque rpm of the engine. A good explanation for the way it works is this: when you go outside jogging you start to breathe in and out faster and harder. Well the same thing goes for a performance engine. The engine is breathing in and out harder and faster, at a higher rpm. If a high performance engine makes power at a higher rpm, then a higher stall speed torque converter is what you need to put more power to the ground quicker.
Are there any other upgrades that I should consider when installing a new torque converter?
You might want to consider a performance tire upgrade such as a "drag radial" tire. Traction will be your biggest problem..... By putting power to the wheels, at a higher rpm, you begin to realize that a suspension upgrade might be a necessary upgrade as well. The only other recommendation is, depending on the application, some performance torque converters create more heat and long term heat kills transmission life. A light bulb that burns twice as bright burns half as long. ... Tests have shown that coolers can increase your cooling capacity by 100%. "
Protorque....
Last edited by JoneZZZ; Dec 26, 2005 at 08:02 PM.
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When you dyno the 5AT......
"THE TRUTH ABOUT DYNAMOMETER READINGS AND HIGH STALL TORQUE CONVERTERS
There is a misconception and a lot of misinformation about the poor vehicle performance numbers that are generated by testing a car with a high stall torque converter on a dynamometer. Most people that are not familiar with how a torque converter operates will automatically think that the torque converter is inefficient. This is totally false and the following facts are why you should not believe the dynamometer numbers while using an unlocked
high stall torque converter. All late model dynamometers have a software program that commands the loading and speed of the vehicle over a certain period of time while making a test pull. The software used in these dynamometers is setup to be used with a locked 1:1 connection between the engine and the rear wheels, such as using a standard shift transmission in 3rd gear or when an automatic transmission has the torque converter clutch
locked. When an unlocked high stall torque converter is used to make the pull and the dynamometer software has not been changed to allow for the fluid coupling differences the dynamometer readings will all be bogus. For instance, the low rpm torque readings will be high due to the torque multiplication of the torque converter being run in partial stall. Likewise,
the high rpm torque readings will be low due to the long period of time the dynamometer takes to allow the torque converter to transition from partial torque multiplication to a hydraulic locked condition. The only cure for this phenomenon is to rewrite the dynamometer software to prevent this from happening. Torque converters with a low STR or low stall are not as adversely affected by this phenomenon. The high rpm transition problems
never occur when the vehicle is being driven or raced normally. Therefore, worrying about what the dynamometer numbers are is a total waste of time. If your dynamometer operator refuses to alter the software to give correct readings then the only things you can do is (1.) lock the torque converter clutch and do the testing, (2.) use the readings you get with an unlocked torque converter as a baseline and continue to tune the car like normal
until you get the best numbers remembering these are just numbers and not the actual horsepower and torque or (3.) use a dynamometer shop that gives you the service you deserve for your hard earned money. The only really true test of the performance of a vehicle is to take it to the track and see what
ET and MPH the car will run."
converter.com
"THE TRUTH ABOUT DYNAMOMETER READINGS AND HIGH STALL TORQUE CONVERTERS
There is a misconception and a lot of misinformation about the poor vehicle performance numbers that are generated by testing a car with a high stall torque converter on a dynamometer. Most people that are not familiar with how a torque converter operates will automatically think that the torque converter is inefficient. This is totally false and the following facts are why you should not believe the dynamometer numbers while using an unlocked
high stall torque converter. All late model dynamometers have a software program that commands the loading and speed of the vehicle over a certain period of time while making a test pull. The software used in these dynamometers is setup to be used with a locked 1:1 connection between the engine and the rear wheels, such as using a standard shift transmission in 3rd gear or when an automatic transmission has the torque converter clutch
locked. When an unlocked high stall torque converter is used to make the pull and the dynamometer software has not been changed to allow for the fluid coupling differences the dynamometer readings will all be bogus. For instance, the low rpm torque readings will be high due to the torque multiplication of the torque converter being run in partial stall. Likewise,
the high rpm torque readings will be low due to the long period of time the dynamometer takes to allow the torque converter to transition from partial torque multiplication to a hydraulic locked condition. The only cure for this phenomenon is to rewrite the dynamometer software to prevent this from happening. Torque converters with a low STR or low stall are not as adversely affected by this phenomenon. The high rpm transition problems
never occur when the vehicle is being driven or raced normally. Therefore, worrying about what the dynamometer numbers are is a total waste of time. If your dynamometer operator refuses to alter the software to give correct readings then the only things you can do is (1.) lock the torque converter clutch and do the testing, (2.) use the readings you get with an unlocked torque converter as a baseline and continue to tune the car like normal
until you get the best numbers remembering these are just numbers and not the actual horsepower and torque or (3.) use a dynamometer shop that gives you the service you deserve for your hard earned money. The only really true test of the performance of a vehicle is to take it to the track and see what
ET and MPH the car will run."
converter.com
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Makeup of a torque converter:
The Impeller
Also known as the pump or driving member; the impeller is driven by the engine. The many curved vanes force fluid outside the converter, creating centrifugal force when spun by the engine.
Stator (w/ One Way Roller Sprag)
The reaction member is a smaller vained rotor located between and turbine. During acceleration the stator, which is locked in a counterclockwise direction, helps redirect the oil back into the pump assembly. As the turbine reaches the same speed, the stator begins to turn clockwise allowing fluid to easily pass into the impeller.
Turbine
Also known as the driven member, looks very similar to the impeller because of its shape and curved vanes. The outer blades of the turbine receive the force fluid of the impeller. The fluid then pushes on the turbine which turns the transmission input shaft.
Clutch and Damper Assembly
Only lock up units, this assembly is what mechanically links the turbine to the front cover. The clutch assembly, when activated by oil pressure, produces a one to one ratio between the motor and the transmission. this in turn lowers engine rpm's and increases fuel efficiency.
Front Cover
The front cover is what mechanically links the pump to the crankshaft of the motor. It also acts as the friction surface on lock up units.
Torque Converter Fact & Function
First, you need to understand the functions of a torque converter. One of the jobs of the converter is to act as a fluid coupling from the motor to the transmission. Another, and a very important function, is torque multiplication. What remains is stall speed, a very misunderstood term. Stall speed is directly related to the amount of torque your engine produces (the greater torque, the higher the stall speed). For example, a converter with a 2800 to 3200 rpm rating might provide approx. 3200 rpm of stall speed behind the big block making 500-plus lbs of torque and in a small block with less torque it's possible to only have a stall speed of 2800. Without knowing how much torque your engine produces, you cannot know how much stall speed a converter is capable of.
Important Factors That Affect A Converters Stall Speed
Vehicle Weight
Vane/Fin Angle
Horsepower
Impeller to Turbine Clearance
Powerband/CamShaft
Stator Design
Torque Rate
Converter Diameter
Gear Ratio
These can be some of the biggest questions you have when looking for a converter....
The Impeller
Also known as the pump or driving member; the impeller is driven by the engine. The many curved vanes force fluid outside the converter, creating centrifugal force when spun by the engine.
Stator (w/ One Way Roller Sprag)
The reaction member is a smaller vained rotor located between and turbine. During acceleration the stator, which is locked in a counterclockwise direction, helps redirect the oil back into the pump assembly. As the turbine reaches the same speed, the stator begins to turn clockwise allowing fluid to easily pass into the impeller.
Turbine
Also known as the driven member, looks very similar to the impeller because of its shape and curved vanes. The outer blades of the turbine receive the force fluid of the impeller. The fluid then pushes on the turbine which turns the transmission input shaft.
Clutch and Damper Assembly
Only lock up units, this assembly is what mechanically links the turbine to the front cover. The clutch assembly, when activated by oil pressure, produces a one to one ratio between the motor and the transmission. this in turn lowers engine rpm's and increases fuel efficiency.
Front Cover
The front cover is what mechanically links the pump to the crankshaft of the motor. It also acts as the friction surface on lock up units.
Torque Converter Fact & Function
First, you need to understand the functions of a torque converter. One of the jobs of the converter is to act as a fluid coupling from the motor to the transmission. Another, and a very important function, is torque multiplication. What remains is stall speed, a very misunderstood term. Stall speed is directly related to the amount of torque your engine produces (the greater torque, the higher the stall speed). For example, a converter with a 2800 to 3200 rpm rating might provide approx. 3200 rpm of stall speed behind the big block making 500-plus lbs of torque and in a small block with less torque it's possible to only have a stall speed of 2800. Without knowing how much torque your engine produces, you cannot know how much stall speed a converter is capable of.
Important Factors That Affect A Converters Stall Speed
Vehicle Weight
Vane/Fin Angle
Horsepower
Impeller to Turbine Clearance
Powerband/CamShaft
Stator Design
Torque Rate
Converter Diameter
Gear Ratio
These can be some of the biggest questions you have when looking for a converter....
Great write up A+. Man i sure would like to see the tranny's from the stock z modified to hold more power and have great response in triptronic and those fast crisp shifts.
By the way i tried what you said in the other thread about when you load the torque converter and your getting to the shift point to release the gas just quite bit to get a faster shift well you can actually tell the difference.
When you just have the gas all the way down throgh the shift you actually feel the torque converter trying to process that power to the next gear kinda like the car gets grabed by the back but instantly gets release but with your method the tranny just goes through the shift super fast. Very good technique just have to get use to do that process. Thanks alot and keep us posted on your finding thanks alot.
By the way i tried what you said in the other thread about when you load the torque converter and your getting to the shift point to release the gas just quite bit to get a faster shift well you can actually tell the difference.
When you just have the gas all the way down throgh the shift you actually feel the torque converter trying to process that power to the next gear kinda like the car gets grabed by the back but instantly gets release but with your method the tranny just goes through the shift super fast. Very good technique just have to get use to do that process. Thanks alot and keep us posted on your finding thanks alot.
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Originally Posted by Fairlady_z33
Great write up A+. Man i sure would like to see the tranny's from the stock z modified to hold more power and have great response in triptronic and those fast crisp shifts.
By the way i tried what you said in the other thread about when you load the torque converter and your getting to the shift point to release the gas just quite bit to get a faster shift well you can actually tell the difference.
When you just have the gas all the way down throgh the shift you actually feel the torque converter trying to process that power to the next gear kinda like the car gets grabed by the back but instantly gets release but with your method the tranny just goes through the shift super fast. Very good technique just have to get use to do that process. Thanks alot and keep us posted on your finding thanks alot.
By the way i tried what you said in the other thread about when you load the torque converter and your getting to the shift point to release the gas just quite bit to get a faster shift well you can actually tell the difference.
When you just have the gas all the way down throgh the shift you actually feel the torque converter trying to process that power to the next gear kinda like the car gets grabed by the back but instantly gets release but with your method the tranny just goes through the shift super fast. Very good technique just have to get use to do that process. Thanks alot and keep us posted on your finding thanks alot.
No problem....glad you found it....."enjoy the ride"....
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Originally Posted by Fairlady_z33
Speaking of the TC which has best put up so far for the Z?
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GEAR RATIOS....
2003 - 2004 Nissan 350Z
Automatic Transmission
Trans Model Code First Second Third Fourth Fifth
RE5R05A All 3.540 2.264 1.417 1.000 0.834
Manual Transmission
Trans Model First Second Third Fourth Fifth Sixth
FS6R31A 3.794 2.324 1.624 1.271 1.000 0.794
Nissanusa....
2003 - 2004 Nissan 350Z
Automatic Transmission
Trans Model Code First Second Third Fourth Fifth
RE5R05A All 3.540 2.264 1.417 1.000 0.834
Manual Transmission
Trans Model First Second Third Fourth Fifth Sixth
FS6R31A 3.794 2.324 1.624 1.271 1.000 0.794
Nissanusa....
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-"the RE5R05A uses a computer inside the transmission on some vehicles (350z for example)"
Power Control Solutions
"The other-on the rear-drive automatics-notes that the rear-drive RE5R05A five-speed automatic transmission is factory-filled with Type J fluid, a new fluid with tailored frictional characteristics to smooth out and also ensure good engagement of the torque converter clutch. It may be similar to some of the other special fluids designed for that purpose, but no one at Nissan can say for sure....."
motor.com
Power Control Solutions
"The other-on the rear-drive automatics-notes that the rear-drive RE5R05A five-speed automatic transmission is factory-filled with Type J fluid, a new fluid with tailored frictional characteristics to smooth out and also ensure good engagement of the torque converter clutch. It may be similar to some of the other special fluids designed for that purpose, but no one at Nissan can say for sure....."
motor.com
Last edited by JoneZZZ; Dec 27, 2005 at 10:27 AM.
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Here's a cut-and-paste from the Nissan-Infiniti TSB (Technical Service Bulletin) addressing Nissan Matic-J fluid, the ATF flavor that's spec-ed for the G35/350Z.......
SERVICE INFORMATION
If the automatic transmission in the new Q45 (F50) or G35 (V35) requires service, a new type of
automatic transmission fluid MUST be used. The new fluid is Nissan Matic-J.
The New Nissan Matic-J
• Only Nissan Matic-J automatic transmission fluid (P/N 999MP-MTJ00P) is specially formulated to meet the
exacting requirements of Infiniti's new 5-speed automatic transmission (RE5R05A).
• The RE5R05A transmission contains new internal components that require the use of
Nissan Matic-J only!
CAUTION:
• Usage of Nissan Matic-D or any other automatic transmission fluid in the RE5R05A 5-speed automatic
transmission will cause deterioration in driveability and transmission durability.
• Do NOT use any other fluid for the RE5R05A 5-speed automatic transmission, only use Nissan Matic-J.
• Use of any other fluid may result in damage to the RE5R05A 5-speed automatic transmission, which will
not be covered by the INFINITI warranty......"
SERVICE INFORMATION
If the automatic transmission in the new Q45 (F50) or G35 (V35) requires service, a new type of
automatic transmission fluid MUST be used. The new fluid is Nissan Matic-J.
The New Nissan Matic-J
• Only Nissan Matic-J automatic transmission fluid (P/N 999MP-MTJ00P) is specially formulated to meet the
exacting requirements of Infiniti's new 5-speed automatic transmission (RE5R05A).
• The RE5R05A transmission contains new internal components that require the use of
Nissan Matic-J only!
CAUTION:
• Usage of Nissan Matic-D or any other automatic transmission fluid in the RE5R05A 5-speed automatic
transmission will cause deterioration in driveability and transmission durability.
• Do NOT use any other fluid for the RE5R05A 5-speed automatic transmission, only use Nissan Matic-J.
• Use of any other fluid may result in damage to the RE5R05A 5-speed automatic transmission, which will
not be covered by the INFINITI warranty......"
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