School me on transmission stalls... v.2800

Discussion in 'OT Driven' started by uofapeter, Apr 24, 2008.

  1. uofapeter

    uofapeter New Member

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    My Chevelle is running a 327 w/ a TH350 transmission with a 2800 tranny stall. I am still at a loss to exactly what the thing does. I've read a ton of shit online and just can't seem to fully understand the purpose nor how it relates to a faster launch. Help me out guys.
     
  2. Mjolnir

    Mjolnir WHM6D > *

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    I'm going to quote stuff from Banks website because I think their write-up is one of the better ones.

    It relates to faster launches based on that highlighted sentence.

    If your engine is spinning faster and making more power when you "engage the clutch" the car will launch harder.

    If you drop the clutch at 500 RPM you get a different result than if you dump it at 4500.

    If your converter has a stall speed of (let's choose random numbers) 1500 RPM your car will drive like you let the clutch out at... 1500 RPM. If your stall is 3000 your car will begin moving as though you let the clutch out at 3000 RPM.

    That's a very rough explanation, but it's a good start.

    Are you experiencing driveability issues on the Chevelle, or are you just wondering if a higher stall would be better?
     
  3. uofapeter

    uofapeter New Member

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    No driveability issues at all. It handles the street and freeway just fine. I just want to know what its all about.

    If this is the case, wouldn't the car not move forward in first till it hit 2800 rpm?

    According to my tach it rolls at about 1500. Is the tach inaccurate or am i still off base?

    The transmission is an automatic btw
     
    Last edited: Apr 24, 2008
  4. Camaro > rice

    Camaro > rice New Member

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    no, it just means that if you torque it up against the brakes, that is the maximum rpm it will go to before it starts to scoot or spin the tires, however if you're not holding the brakes it will still move it a lower rpm. it will still rev up slightly higher than a stock convertor before it starts moving but not all the way to the stall speed.
     
  5. Mjolnir

    Mjolnir WHM6D > *

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    TC's are actually big fluid pumps so even though you aren't at stall speed you're still transmitting power to the tranny from the motor.

    It's kind of like you're slipping the clutch. The car will still move, just not as fast as if you simply dumped it. (I know your Chevelle is an automatic, but comparing an auto stall speed to the engagement point on a clutch helps some people with envisioning the process.)

    In your car it sounds like the TC is pumping enough fluid to get you rolling around 1500, but it won't be at "max" capacity until 2800. If you power brake it the tach should go to around 2800 and hold there. If you're cruising on Friday night and want to crush some kid in a Civic that'll be useful but it doesn't really matter for a DD.

    Unless you plan on racing or swapping out the motor I wouldn't worry about it. If the car drives fine and you don't feel like it's bogging at the start or "jumping" unintentionally, leave it alone.

    If you're going to race and aren't worried about streetability you could dyno the car and get a converter that stalls closer to your peak power.

    If you're going to swap motors (maybe a BBC?) and build a cruiser/driver you might consider a lower stall to take advantage of big block torque.
     
  6. uofapeter

    uofapeter New Member

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    OK i see. That makes sense. I'm not looking to change it, just wanted to be a little more in tune to what i've got here. Thanks for the help.
     
  7. deusexaethera

    deusexaethera OT Supporter

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    Saying that the stall speed is the speed at which the torque converter "engages" is misleading; the torque converter is always engaged. (It can lock up to bypass the fluid coupling to get better highway MPG, but that's a totally different thing.) The stall speed is the RPM at which, when the wheels are stopped and the gas pedal is floored, the immovable output turbine will create so much drag on the spinning input turbine that the engine will be unable to continue revving up. It represents the torque converter's mazimum ability to convert engine RPM back into low-speed torque that the car can use to start moving.

    Also, the torque converter isn't really a fluid pump, so much as it is two impellers designed to catch the fluid being thrown at them and throw it back, transmitting torque in the process. The motion of the transmission fluid looks like a torus, sort of like a coil spring wrapped around into a circle.

    EDIT: I DID NOT FUCKING GOOGLE THAT. Just wanted to get that out of the way before someone gave me shit about it.
     
  8. Smelly-Kitten

    Smelly-Kitten Dept. of Redundancy Department *Side Pipes

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    I'ma keep my eye on this thread so people don't steer the the thread into too much BS and hearsay
     
  9. dr.zed

    dr.zed DR.ZED OT Supporter

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    you just googled that
     
  10. CJPA

    CJPA New Member

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    :rofl:
     
  11. Toke

    Toke New Member

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    :rofl::rofl::rofl:
     

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