Spring rate?

[BoondocK5]

How do you determine spring rate needed for a particular vehicle?
Do you weigh whatever half the vehicle you working with, take that weight, divide it in half and then match a spring weight to that weight? One (set) of spring(s) per side.

call it curiosity...

 

[Greg72]

Close....

You'd also have to remove the weight of the axles, tires, and stuff that is not actually suspended by the springs (knows as "unsprung weight")

Remember, a spring rate is measured in Lbs/in.....not just Lbs. You will lose an inch of lift (free arch) as you add the rated weight to the spring.

A 400Lb/in spring can hold 800Lbs, but will lose 2" of arch in the process...etc.

 

[Hogback Fabrication]

The spring rate you want depends on what the vehicle is intended for.

As mentioned, the axles and tires/wheels are not sprung so don't count toward the weight the springs have to hold.

One more thing, leaf spring rates are not linear. The spring might be rated for 400 lbs/in but that only applies for the first inch. It might take 500 lbs to compress the spring another inch after that.

 

[blazinzuk]

http://www.therangerstation.com/tech_library/leafspringrate.htm

I have the formula written down somewhere, without an accurate way to measure the weight of you your truck it is just a point of curiosity.

Calculated rate and actual rate are going to be different too as has been said because a leaf spring rate changes