Technical Description For Leaf Springs ?
07-17-2011, 05:28 PM
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Technical Description For Leaf Springs ?
Does anyone have a web site that they know of which describes the correct technical way to describe an automotive leaf spring, other that the linear dimensions.
All the sales folks say; medium or heavy duty, some give arch dimension, some give lift dimension; but few if any give the spring deflection. I believe that spring deflection is the more descriptive nomenclature to use when describing a leaf spring. I believe it is X number of pound will deflect the spring one inch.
I was talking with the folks at "Rusty's" and was duscussing spring arch. They said the measured arch is meaningless, it is the rated deflection which reveals what a particular spring will do after installation.
Webb
All the sales folks say; medium or heavy duty, some give arch dimension, some give lift dimension; but few if any give the spring deflection. I believe that spring deflection is the more descriptive nomenclature to use when describing a leaf spring. I believe it is X number of pound will deflect the spring one inch.
I was talking with the folks at "Rusty's" and was duscussing spring arch. They said the measured arch is meaningless, it is the rated deflection which reveals what a particular spring will do after installation.
Webb
07-17-2011, 06:33 PM
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Year: 1988
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Engine: AMC242
As I recall, there are three important dimensions when measuring a leaf spring physically:
- Spring arch. This is typically measured at rest, from the centre of the screw eyes to the centre of the pack at peak arch.
- Spring width. Self-explanatory.
- Spring length. This can be further divided, but is typically measured along the proper. However, I've seen four useful numbers for length:
-- Spring length, measured from spring eye to spring eye, along the arch.
-- Spring length, measured directly from eye-to-eye (absolute length between mounting points.)
-- "Short" length - distance between the centre pin and the closest spring eye, measured along the arch.
-- "Long" length - distance between the centre pin and the farthest spring eye, measured along the arch.
The other significant measurements would be spring eye ID (which corresponds to bushing OD,) centre pin size, and bushing ID - but the latter two can be changed (within reason.)
Spring rate (pounds of force per inch of deflection) can generally be calculated once spring characteristics are known, just as it can be calculated from measurements for coil springs. I don't recall the formulae, but they may be readily referenced. Check Machinery's Handbook or Bosch Automotive Handbook, and they may be online as well. Also, any decent text on suspension design should be able to tell you what you want to know. (The only variable left out of the calculation for spring rate would be steel temper & alloy, but springs steels are generally close enough to each other that you'll get a useful number without it.)
- Spring arch. This is typically measured at rest, from the centre of the screw eyes to the centre of the pack at peak arch.
- Spring width. Self-explanatory.
- Spring length. This can be further divided, but is typically measured along the proper. However, I've seen four useful numbers for length:
-- Spring length, measured from spring eye to spring eye, along the arch.
-- Spring length, measured directly from eye-to-eye (absolute length between mounting points.)
-- "Short" length - distance between the centre pin and the closest spring eye, measured along the arch.
-- "Long" length - distance between the centre pin and the farthest spring eye, measured along the arch.
The other significant measurements would be spring eye ID (which corresponds to bushing OD,) centre pin size, and bushing ID - but the latter two can be changed (within reason.)
Spring rate (pounds of force per inch of deflection) can generally be calculated once spring characteristics are known, just as it can be calculated from measurements for coil springs. I don't recall the formulae, but they may be readily referenced. Check Machinery's Handbook or Bosch Automotive Handbook, and they may be online as well. Also, any decent text on suspension design should be able to tell you what you want to know. (The only variable left out of the calculation for spring rate would be steel temper & alloy, but springs steels are generally close enough to each other that you'll get a useful number without it.)
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