What breaks automatic transmissions and torque converters - horsepower or torque?
#1
What breaks automatic transmissions and torque converters - horsepower or torque?
It seems like automatic transmissions and torque converters are rated at either a max horsepower, or max torque, or sometimes but not always both. So which one actually causes them to fail?
My first guess is torque because that is how hard something is turning... and by turning too hard against resistance, eventually something's going to break. But where does that leave horsepower? And why is it used in rating transmissions and converters?
My first guess is torque because that is how hard something is turning... and by turning too hard against resistance, eventually something's going to break. But where does that leave horsepower? And why is it used in rating transmissions and converters?
#3
TECH Fanatic
HEAT is the #1 cause of transmission failure. Horsepower and Torque would be secondary. Some companies like FLT doesn't even advertise a "Max" hp/tq number because it depends on the application.
#4
Yea, I know heat is really bad for transmissions... I'm thinking more about catastrophic failures, not the failures that result from continuously high trans temps.
So if it's all about torque, why do some companies use max horsepower specs on converters and transmissions?
So if it's all about torque, why do some companies use max horsepower specs on converters and transmissions?
#5
Moderator
HP is basically Torque multiplied by RPM.
There certainly is a maximum torque for any mechanical device.
But RPM is also an issue as excessive RPM will cause centrifugal force to cause bulging, bending and therefore bearing failure. Excessive RPM in an automatic transmission will cause the fluid to pool/move in unintended ways reducing clutch pressure.
I would "guess" that unless you are exceeding 7000 rpm, then max torque is what you have to worry about. And as mentioned, overheating will kill things long before the max torque is reached.
There certainly is a maximum torque for any mechanical device.
But RPM is also an issue as excessive RPM will cause centrifugal force to cause bulging, bending and therefore bearing failure. Excessive RPM in an automatic transmission will cause the fluid to pool/move in unintended ways reducing clutch pressure.
I would "guess" that unless you are exceeding 7000 rpm, then max torque is what you have to worry about. And as mentioned, overheating will kill things long before the max torque is reached.