MustangTamer

iTrader: (1)

hi guys i know this may seem like a "noob" question but what is a transmission stall? how does it work and is it something i can have on my transmission and it still be a daily driver car? thanks for any input. i just got my f body a few months back so im still learning

Apeiron

"Stall" isn't a part, it's a characteristic of the torque converter.

89_RS

Simply put, stall is the point at which the turbine pump and input turbine are freewheeling around the stator coil. Before this point, the pump rotates one way and the input rotates another way. After the stall, the pump and input turbines reverse rotation and continue on there merry way.

For a clearer picture:
http://auto.howstuffworks.com/auto-p...-converter.htm

MustangTamer

iTrader: (1)

thanks for the info. but what does this do? quicker launch? im still confused.

ASE doc

"Stall speed" refers to the rpm at which a torque converter stops slipping. A converter is basically a turbine pump. As the input, or engine side is driven by the engine, it creates pessure against the internal turbine of the pump causing it to turn as well. At low engine speeds, the pressure and turning force against the turbine is small enough that the vehicle can sit still without the engine stalling. As engine speed increases, the pressure against the turbine increases and at the torque converter's "stall speed", the turbine becomes hydraulically locked to the converter body and turns at the same speed as the engine.

Every torque converter has a "stall speed". Converter stall speed is controlled by the design of the internal parts and varies by application. A stock converter in an 87 Z28 is 1,800 rpm. Increasing stall speed from stock allows the engine to reach higher rpm before the full load of pulling the vehicle is placed upon it. This is generally done with larger cams as the larger cam raises the rpm point at which the engine reaches its torque peak. The down side to higher stall speeds is that the converter spends more time slipping which heats the trans fluid, placing greater stress on the transmission.

Driving a 3,500 stall converter in town will get old very fast. It feels like the trans is in neutral as you take off from a light at anything less than 1/2 throttle. Stall speeds any greater than 3,000 are really only intended for drag strip use. However, there is a vast array of stall speeds between stock and 3,500. I run a 2,300 stall speed converter. With the low first gear of the 700R4 (3.06:1) and 3.42 rear gears, 2,300 seems to be plenty for my engine, even with the huge cam.

ASE doc

And yes, a higher stall converter creates quicker launches. Not really helpful with stock tires though since tire spin will be your biggest problem anyway.

89_RS

It depends on the stall speed. Stall speed is listed in rpm's, so a converter with a 2000rpm stall will stall when the engine reaches 2000rpm.

Lower stall speeds are good for fuel economy and towing and are what come from the factory. 2000-3000 stalls are what you can expect to see in street cars. Anything over 3000 is pretty much for a race car unless you have the proper setup

MustangTamer

iTrader: (1)

i understand now. thanks ASE doc and 89_rs.

AlkyIROC

A higher stall converter allows the engine to get into the cam's powerband quicker. For street/strip use, a converter that stalls about 500 rpm into the powerband is good. For full race, a converter that stalls about 1000 rpm into the powerband is better.

It a camshaft is rated as 1800-6500 rpm, you would want a converter that stalls around 2300 to achieve the best performance.

Too much stall speed can be just as bad as not enough. As mentioned above, when driving around at less than the converter's stall speed, the converter has to slip. This slipping builds heat. Heat kills transmissions. Any transmission with a converter with a higher than stock stall speed needs an external oil cooler.

A rated stall speed is just that. A rating. The speed it actually stalls at depends on how much torque is put into it. A converter that stalls at 2300 behind one engine may stall higher or lower behind another. The only way to know a converter's true stall speed is with a transbrake.

My converter is for full race. With the transbrake on and the engine at WOT, the converter stalls at 6200 rpm. I've launched anywhere between 4500 and 6200 rpm. I shift at 7400 and the rpms drop to 6400 after the shift. I cross the finish line at 7400. I want some deeper gears in the diff and the only way to do that is to get this converter's stall speed lowered a few hundred rpm.

Torque converter info
http://www.hardtail.com/techtips/sel...converter.html
http://www.hardtail.com/techtips/torqueconverters.html
http://www.hardtail.com/techtips/converter%20stall.html

stealthroc89

Should a vehicles weight be factored into selecting a stall? If so how much?

Zepher

iTrader: (1)

Here is my brothers 96 Trans Am with an LS1 conversion and a 4000 stall.
The high stall keeps the engines RPM up higher during shifts to maximize power.
http://www.youtube.com/watch?v=V7yhFo33ilQ