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I am far from a mechanical doofus, but I can not understand how a stall converter in an Automatic gearbox works. I am 100% puzzled as to how it works, what it does & it's main function is. Someone explained it to me once, but I couldn't understand much of the explanation. I hear about a stall converter's "stall speed" increased to, say, 2500rpm. What the hell does all this mean? Can someone explain who, what, when, where & why a stall converter is?

Thanks
 

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stall speed is like dropping the clutch in a stick at that speed.

if you don't rev the motor to at least that speed before you take off, it's like riding the clutch...

there's more, but i'm sure that others will explain
 

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then why install higher stall speed TC's? i would want a lower stall speed TC
 

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Discussion Starter #4
flylwsi said:
stall speed is like dropping the clutch in a stick at that speed.

if you don't rev the motor to at least that speed before you take off, it's like riding the clutch...

there's more, but i'm sure that others will explain
Ah, sort of like dumping the clutch, correct? So, if the stall speed is set at 3000rpm, then the car will not take off/start moving (the torque converter will not "lock/engage") until 3000rpm?

I have an article in which a 2JZ-GTE was swapped into a Soarer (originally it had a 1JZ-GTE), & the article said that they needed to increase the automatic gearboxes stall speed to something like 5000rpm (the turbo was some huge thing like a T78 & they raised the stall speed to allow the turbine to spool up). Does this sound right?
 

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mls said:
Ah, sort of like dumping the clutch, correct? So, if the stall speed is set at 3000rpm, then the car will not take off/start moving (the torque converter will not "lock/engage") until 3000rpm?

I have an article in which a 2JZ-GTE was swapped into a Soarer (originally it had a 1JZ-GTE), & the article said that they needed to increase the automatic gearboxes stall speed to something like 5000rpm (the turbo was some huge thing like a T78 & they raised the stall speed to allow the turbine to spool up). Does this sound right?

yes it does
 

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from what i've read in honda tuning it controls the tranny fluid that runs through so when you have a stall speed of 3000 then the tc won't let the fluid through until after 3000 .....3000 is the max rpm it will let you go before the fluid comes through. They make the stall speed high and lower by controlling the amount of resistance on the tc. i'm pretty sure its something like that. Peace.
-Mike
 

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stall is approached when the tran shaft is locked and not rotating(ie locked via brake pedel pressed - wheels stopped). the fluid pressure builds to the stall point

under normal acceleration a higher stall converter , given same or better quality than stock, will accerlate the same unless the stall speed is drastically higher (~3000 higher than stock etc.)

high quality stall converters versus stock may improve regular acceleration and acceleration under full throttle.

take example of v8 car. installed with long duration cam, it lost say 75 lb feet of tq at 1000 rpms and gained power 1000 rpms higher. launching at 1200 rpms (stock converter) is slow as hell off the line. installing new converter that stalls at 2500, launch is now set at a point that is juicier in powerband and the off-line performance is restored.
 
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