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#1
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Stall Speed Converter
When I start the car cold and take off in first the converter stalls at about 2800, which is correct and what the converter is rated at, but when I continue driving and come to a stop sign and I take off again there is very little stall, maybe 1000 rpm. This is wrong isn't it ? I can't believe it should only stall the first time when cold. Do I need to stay stopped longer ? Any help would be appreciated.
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#2
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When you first start the car and take off, usually the converter is not full of fluid, so it slips more than normal. Once the converter is full (usually after driving a short distance) the converter stalls at it's normal speed.
If the "normal speed" is only 1,000 RPM (and is rated higher), you may have a bad converter or your engine has weak low RPM torque output. This almost sounds like the normal GER torque converter junk. |
#3
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Just a little more information
I have a 74 Dodge Truck with a 69 440 and a 727TF.
The stock stall torque convertor would stall high when first taking off but then would go at around 1000 rpm. I bought a so called 3000 stall off of ebay and it reacts similiar in that a real high stall when cold but once warmed up will take off at a lower rpm at around 1200. I can hold the brakes and get the rpm's up to about 2500 rpm's before it will overcome the brakes (drum). The original TQ would only let you get up to around 1500 before overcoming the brakes. |
#4
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1st, Happy Birthday jlcoffell. I'm thinking this one over and can't make sense of it. Why would it overcome the brakes at a different rpm with a different carb? The more torque an engine produces, the more stall it will have, i.e small block v big block. But if it made less torque (lower rpm) why wouldn't the brakes hold v the the higher stall?
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#5
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Sorry, type error
When I posted the reply I meant to say
with the original TC as in Torque Convertor not TQ. Sorry, I have a project where I have been working on a thermoquad (TQ) and just have it on the brain. |
#6
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The TC is a B&M 2400 Holeshot it is rated to stall between 2400 & 2800 RPM. Has anyone had problems with this brand ?
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#7
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How are you checking stall?? The best way is to check in Drive, moving,without the trans shiftiing down, floor it & see what RPM it goes to. If you are thinking the RPM that you can take it to on the brakes , that is not stall speed.
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#8
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Quote:
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#9
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Where the RPMs go to when you pull out is not the true stall speed. The way I described is the only true way to check stall. Stall in the converter is reached when the converter is "locked up" which will be at a higher RPM than what the it takes to move the vehicle.
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#10
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Just to clarify this a bit more. Stall speed is the point at which the converter "locks up". True, it's not really locking up the way a true lockup converter will, but it's that point at which, if the output shaft is not allowed to turn, the input shaft can turn no faster. Any additional power going into the converter will be converted to heat. That's why high-stall converters should have transmission coolers.
If your car wants to move at 1000 RPM, but you can hold it with the brakes, that is definitely NOT your stall speed. If you hold the brakes, and the converter overpowers the brakes at 2500 RPM, then 2500 RPM is STILL NOT your stall speed. Since most high-powered engines will overpower the brakes, the method Mopardad gives is the best way to telll what your true stall speed is. This will give you the speed that your converter will "flash" to, which should be up somewhere around 2800 RPM if you have what you think you do. This lets your engine move up into its torque band when you need the power, but still lets you cruise with some efficiency at lower engine speeds when you're not at full power. |
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