[69malibu3speed]

I don't do automatics, at least not in my toy cars. I keep seeing stall speed mentioned when referring to automatic transmissions. Someone explain please.......thanks

[gUmBaLL68Malibu]

Well i am no expert but what i understand is this. The stall is the speed @ which the motor and transmission are spinning and the same rate. The stall like lets say you had a 3000 stall, the motor would spin to 3000 much faster so the transmission and motor are spinning the same. That is what was told to me. I had a 3000 stall in my car for the last 4 years and basicly it would rev to 3000 real quick and then you could feel the car grab harder once it reached that point. I have also been told the higher the stall the more gas you waste but i have also been told that you shouldn't worry about gas mileage if you own an old car like this.

Anyway hope this helped and if i am totally wrong someone please chime in.

[Oldani Motorsports]

Stall is measured in three different ways. TRUE, BRAKE and FLASH Stall.

True stall is measured with the transmission locked (transbrake) and the drive shaft still. The throttle is then fully depressed and held to obtain the holding RPM of the torque converter. This is the true stall speed.

Foot brake stall is attained with the transmission in gear and the brakes depressed fully. Now slowly apply the accelerator. The RPM the engine reaches the moment before the tires spin is known as the brake stall. Brake stall is not a consistent way to measure your stall converter and has many variables. This method will be lower then true stall; often by at least 500 RPM

Flash stall is checked while the car is in motion. While rolling at a slow speed fully depress the throttle to see where the RPM will flash (or peak) to. This method will not be true if tires spin or the car is rolling too fast. Due to the turbine already turning in the torque converter (it is the part the input shaft is splined into) you end up with less torque multiplication. This will give you a lower stall reading than the same converter's true stall rating; often by at least 200 RPM and sometimes quite a bit more depending on the converter design.

[Herb]

How about this from a novice with a limited understanding and vocabulary:

The purpose of the torque converter is to smoothly transfer the power of the engine to the transmission and drive train, just as a clutch does. Below the stall speed of the converter, very little power (torque) of the engine is transfered because the converter (by design) is coasting. At or above the rated stall speed the converter transfers significant power (torque) of the engine.


Here's a link to explain how it works.
http://auto.howstuffworks.com/torque-converter.htm


Stall Speed:
Think of the propeller of a single engine plane that is idling at the end of a runway. There is very little thrust created by the propeller due to the low speed at idle. Increase the engie speed (and the propeller speed) and it really pulls the plane forward because the prop really bites into the air. The vanes inside a torque converter do the same thing in the transmission fluid inside the converter. Change the angle or pitch of the vanes during manufacturing and you change the speed at which they "really bite" into the fluid and transfer that spin (and torque or force) to the other half of the converter which is connected to the drive train. Below that speed, just like the idling plane propeller, there is still bite, but not as much. That's the speed at which the converter "stalls" so to speak, or doesn't really transfer much power.

I belive the advantage of this is to allow the engine to rev up into the area of the power band in which it is developing torque, before the coverter begins to load it down by transfering that torque to the drive train.

Like I said, I'm just a novice so if I'm wrong Steve can correct me.