checking stall
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Its all very vague-it would seem in this day of modern technology they could bolt on a converter to some kind of spinning machine and a digital gauge could tell you what stall speed it locks up at or if the converter is good. i cant imagine they would have to take the whole converter apart to tell if its still good or what the stall is.
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pat83t
Guest
UNDERSTANDING STALL SPEED
All torque converters have a specific "stall speed" which can vary from one vehicle application to another, even when similar transmissions are used. So if the torque converter needs to be replaced for any reason, it's very important to make sure the replacement unit is the correct one for the application. If the stall speed is not correct, it can have an adverse effect on driveability, performance and transmission longevity.
If you're not familiar with stall speed, it is the maximum rpm at which the engine will turn before the converter will allow no more slippage. In other words, it's the maximum speed at which the impeller will turn before the turbine starts to move.
The stall speed of a torque converter is determined by its diameter and the size of the stator wheel. Generally speaking, the smaller the converter, the higher the stall speed. A 10-inch torque converter, for example, typically has a higher stall speed than an 11-inch converter.
A higher stall speed generally gives more torque multiplication, which improves acceleration. The highest amount of torque multiplication is achieved when the engine reaches its maximum stall speed just before the car starts to move. It peaks out as the transmission starts to turn, and then diminishes as the speed of the turbine wheel catches up with the impeller.
I got this from: http://www.babcox.com/editorial/bf/bf90054.htm
All torque converters have a specific "stall speed" which can vary from one vehicle application to another, even when similar transmissions are used. So if the torque converter needs to be replaced for any reason, it's very important to make sure the replacement unit is the correct one for the application. If the stall speed is not correct, it can have an adverse effect on driveability, performance and transmission longevity.
If you're not familiar with stall speed, it is the maximum rpm at which the engine will turn before the converter will allow no more slippage. In other words, it's the maximum speed at which the impeller will turn before the turbine starts to move.
The stall speed of a torque converter is determined by its diameter and the size of the stator wheel. Generally speaking, the smaller the converter, the higher the stall speed. A 10-inch torque converter, for example, typically has a higher stall speed than an 11-inch converter.
A higher stall speed generally gives more torque multiplication, which improves acceleration. The highest amount of torque multiplication is achieved when the engine reaches its maximum stall speed just before the car starts to move. It peaks out as the transmission starts to turn, and then diminishes as the speed of the turbine wheel catches up with the impeller.
I got this from: http://www.babcox.com/editorial/bf/bf90054.htm
The problem is that converters stall differently with each different combination. It all depends on alot of things, like tranny, pressure, torque, etc... A converter that stalls to only 2800 behind a 350 may stall to 3200 behind a 454. There's also foot break stall and flash stall. If I'm correct, converters normally have a higher "Flash" stall than FB stall. At least the three I ran did.
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pat83t
Guest
I agree, but according to my stock specs the OEM converter was to have a stall speed of 2025 rpm. By doing this "test" the other day I topped out at 1350rpm. I already suspected my converter was pulling an Elvis on me but now I am sure.
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pat83t
Guest
"To perform a stall test:
1. Block the wheels. Do not allow anyone to stand in front of or behind the vehicle.
2. Start the engine and place the transmission in Drive.
3. While pressing firmly on the brake pedal with your left foot, use your right foot to press down on the accelerator pedal. Increase engine speed until engine rpm will go no higher. Then release the accelerator pedal and allow the engine to return to idle. Note the maximum stall speed rpm (typically 1,500 to 2,200 rpm) and compare to specs.
If the engine stall speed is higher than specifications, the transmission is slipping (probably a holding clutch or band).
If the engine stall speed is lower than specifications, the torque converter is defective (stator is slipping), or the engine is not producing normal power (engine problem)."
That is how I did mine. I know the motor is not the problem. with the way it is built I should be alot faster than I am and used to be faster. then when I serviced the tranny I found some clutch material but it wasn't from the tranny. Tranny shifts fine but it just seems as though the car is fighting itself and is being held back. Almost like carburation problems but it isn't, and it is getting worse.
1. Block the wheels. Do not allow anyone to stand in front of or behind the vehicle.
2. Start the engine and place the transmission in Drive.
3. While pressing firmly on the brake pedal with your left foot, use your right foot to press down on the accelerator pedal. Increase engine speed until engine rpm will go no higher. Then release the accelerator pedal and allow the engine to return to idle. Note the maximum stall speed rpm (typically 1,500 to 2,200 rpm) and compare to specs.
If the engine stall speed is higher than specifications, the transmission is slipping (probably a holding clutch or band).
If the engine stall speed is lower than specifications, the torque converter is defective (stator is slipping), or the engine is not producing normal power (engine problem)."
That is how I did mine. I know the motor is not the problem. with the way it is built I should be alot faster than I am and used to be faster. then when I serviced the tranny I found some clutch material but it wasn't from the tranny. Tranny shifts fine but it just seems as though the car is fighting itself and is being held back. Almost like carburation problems but it isn't, and it is getting worse.
Jerryl
Tall Unvaccinated Chinese Guy
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- Dec 14, 2004
- Messages
- 9,644
Good thread!
Deserves a TTT IMO.
Deserves a TTT IMO.
JRNYMNDAVID
MACSTURBOTA
- Joined
- Jun 25, 2006
- Messages
- 152
This Is The Way
Providing you have a boost gauge w/vac reading hooked up.
Put car in 2ND and hold on foot brake.Accelerate until vacuum reaches "0".
Check RPMs."That" is your actual stall speed.Stall speeds differ from advertized specs,due to HP,torque,etc.This will work with stock or aftermarket converters.
49-blues said:
Providing you have a boost gauge w/vac reading hooked up.
Put car in 2ND and hold on foot brake.Accelerate until vacuum reaches "0".
Check RPMs."That" is your actual stall speed.Stall speeds differ from advertized specs,due to HP,torque,etc.This will work with stock or aftermarket converters.
Jerryl
Tall Unvaccinated Chinese Guy
- Joined
- Dec 14, 2004
- Messages
- 9,644
Understand. That is why it is SO DANG hard to get a converter with the "actual stall" you need. Someone correct me if I am wrong.JRNYMNDAVID said:Providing you have a boost gauge w/vac reading hooked up.
Put car in 2ND and hold on foot brake.Accelerate until vacuum reaches "0".
Check RPMs."That" is your actual stall speed.Stall speeds differ from advertized specs,due to HP,torque,etc.This will work with stock or aftermarket converters.
I think my 2800-3000 stall actually stalls around 2200.
Robert Kastle
New Member
- Joined
- Mar 12, 2004
- Messages
- 81
Thats why it is such a big help if the customer is able to provide a dyno chart that maps the torqure curve of the engine along with the vehical weight and other mods.
I am only able to floor brake my car to ~2300rpm before the rear tires start to spin (p235 radials). This is with a converter rated at 3400rpm. Now if I place my car in 3rd gear and floor it from a roll at about 2000rpm (~44mph) the tach runs up to ~4300-4500rpm and stays there till about 80mph then the rpm's start to increase with speed.
On this board you will here people talk about,,,foot stall,,,flash stall and stall on the "T-Brake".
I am only able to floor brake my car to ~2300rpm before the rear tires start to spin (p235 radials). This is with a converter rated at 3400rpm. Now if I place my car in 3rd gear and floor it from a roll at about 2000rpm (~44mph) the tach runs up to ~4300-4500rpm and stays there till about 80mph then the rpm's start to increase with speed.
On this board you will here people talk about,,,foot stall,,,flash stall and stall on the "T-Brake".
grocerygetter
Active Member
- Joined
- Mar 8, 2005
- Messages
- 1,203
My bathroom stall is about 2300...
good thread.
good thread.
