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Just got to thinking the other day; we're always talking about the spring rates of coils, but never leaf springs. Are leafs more dynamic than coils? Does the spring rate change as it cycles through it's travel (i.e.-progressive)?
 

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mudferret said:
Just got to thinking the other day; we're always talking about the spring rates of coils, but never leaf springs. Are leafs more dynamic than coils? Does the spring rate change as it cycles through it's travel (i.e.-progressive)?
Bump, because I want to know why you care. ;) Are you going to phone me back or what? I sold your coils for you.
 

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SteveO said:
Bump, because I want to know why you care. ;) Are you going to phone me back or what? I sold your coils for you.
It's about 11pm so I'm sure you've been asleep for at least two hours now :)

I'll get in contact with you tomorrow.
 

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mudferret said:
It's about 11pm so I'm sure you've been asleep for at least two hours now :)

I'll get in contact with you tomorrow.
2.5 actually, you sleep when you can get it with the baby. Give me a shout at work if you want between 10-1 210-5628 ..Steve
 

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Mr Mud. I looked in a book titled "Chassis Engineering" by Herb Adams, and it has a fomula to calcuate leaf sping rates:

Leaf Spring Rate = (WN/12) x (1000t/L)^3

W = Width of leaves
N = Number of Leaves
T = Thickness of 1 leaf (inches)
L = Length of spings (inches)
12 = a contant for all leaf springs
 

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Ted said:
Mr Mud. I looked in a book titled "Chassis Engineering" by Herb Adams, and it has a fomula to calcuate leaf sping rates:

Leaf Spring Rate = (WN/12) x (1000t/L)^3

W = Width of leaves
N = Number of Leaves
T = Thickness of 1 leaf (inches)
L = Length of spings (inches)
12 = a contant for all leaf springs

That’s a good equation that you posted!!!

That equation is for a specific “idealized” spring that does not apply to everything. It is intended to calculate what is known as a “uniform stress spring”
It is assuming that the center pin is in the middle of the spring “most are not”
And that the leafs are arranged in certain lengths were each leaf is progressively shorter so that if you disassembled the pack and lay the leafs side by side it would form a triangle from the center pin outward. “I will post a diagram soon”
Almost all springs have 2 full length leafs, this changes rate from the equation
The factory springs have an overload that makes the rate more progressive. And harder to calculate
Shackle angle can also be used to make the rate progressive or even digressive. A poorly designed spring can put the shackle at an angle that makes it digressive and prone to bottom out even if its initial rate is good.

You can use that equation to get a ROUGH estimate of an aftermarket spring but the factory spring with mostly full length leafs and an overload would not work.

To use it for an aftermarket spring you will have to analyze the front and back of the springs separately and then add them together because of the center pin not being in the middle
 

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DylanDr said:
That’s a good equation that you posted!!!

That equation is for a specific “idealized” spring that does not apply to everything. It is intended to calculate what is known as a “uniform stress spring”
It is assuming that the center pin is in the middle of the spring “most are not”
And that the leafs are arranged in certain lengths were each leaf is progressively shorter so that if you disassembled the pack and lay the leafs side by side it would form a triangle from the center pin outward. “I will post a diagram soon”
Almost all springs have 2 full length leafs, this changes rate from the equation
The factory springs have an overload that makes the rate more progressive. And harder to calculate
Shackle angle can also be used to make the rate progressive or even digressive. A poorly designed spring can put the shackle at an angle that makes it digressive and prone to bottom out even if its initial rate is good.

You can use that equation to get a ROUGH estimate of an aftermarket spring but the factory spring with mostly full length leafs and an overload would not work.

To use it for an aftermarket spring you will have to analyze the front and back of the springs separately and then add them together because of the center pin not being in the middle
Thanks for the input. I know my deavers have offcenter pins. I look foward to your diagram.
 
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