Clutch Drop @3k & 7k Shock Loads?
03-06-2004, 09:49 AM
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Clutch Drop @3k & 7k Shock Loads?
I did a search and could not find anything but I was wondering if there is a way to quantify the type of shock loading for a 3k compared to 7k cluth drop. Assuming the transmission receives the brunt of the load. Also not sure of how slip verses wheel hop would make a difference. I know the torque at 3k and 7k would come into play but would you relate that to RPM? Any thoughts? I just thought it would be nice to see the difference between the two hopefully showing how terrible a 7k drop is.
03-06-2004, 07:56 PM
#2
Well, I can't give you an exact answer, but I can take a stab at it using basic physics.
When you are talking about shock loading, you are talking about a system (the driveline in this case) absorbing a significant amount of energy in a short period of time. One way to look at the quantities involved is to look at how much kinetic energy is stored in the spinning rotors at 3,000 and 7,000 rpms.
Normally, the kinetic energy of a rotating mass is proportional to the square of the angular velocity. In otherwords, if you double the engine speed, the amount of kinetic energy stored in the spinning rotors is 4x. So, at 7,000 rpm the engine has 5.44 times as mutch potential to do damage as when it is spinning at 3,000 rpm (yes, I know the rotors spin at 1/3 the crank speed, but the 5.44 ratio is still the same).
Now, this is really sophomoric - there is much more going on, especially when you consider that you are adding throttle to keep the rpms high, so most of the kinetic energy isn't transferred immediatly. The truth is, the actual shock loading is limited by traction - you could launch at 9,000 rpm and the actual shock loads probably wouldn't be much worse than a 7,000 rpm launch- you would just spin the tires more (and be slower because of it).
In the end a good dose of mechanical empathy goes along way towords extending the life of your car.
Anybody else have a better description?
When you are talking about shock loading, you are talking about a system (the driveline in this case) absorbing a significant amount of energy in a short period of time. One way to look at the quantities involved is to look at how much kinetic energy is stored in the spinning rotors at 3,000 and 7,000 rpms.
Normally, the kinetic energy of a rotating mass is proportional to the square of the angular velocity. In otherwords, if you double the engine speed, the amount of kinetic energy stored in the spinning rotors is 4x. So, at 7,000 rpm the engine has 5.44 times as mutch potential to do damage as when it is spinning at 3,000 rpm (yes, I know the rotors spin at 1/3 the crank speed, but the 5.44 ratio is still the same).
Now, this is really sophomoric - there is much more going on, especially when you consider that you are adding throttle to keep the rpms high, so most of the kinetic energy isn't transferred immediatly. The truth is, the actual shock loading is limited by traction - you could launch at 9,000 rpm and the actual shock loads probably wouldn't be much worse than a 7,000 rpm launch- you would just spin the tires more (and be slower because of it).
In the end a good dose of mechanical empathy goes along way towords extending the life of your car.
Anybody else have a better description?
Last edited by GeorgeH; 03-06-2004 at 08:09 PM.
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