Thread: spring identification

you could try looking here, although your springs may have settled in height a little.
http://members.shaw.ca/jbarge/springinfo.html

For same material eg. steel (type of steel doesn't matter as modulus of rigidity does not change much):

Increasing wire diameter (d). increases spring rate. For reasonably small increases in wire diameter, the rate is proportional to d^4. ie. (d X d X d X d).

Say rover spring 1 is identical to rover spring 2 except wire dia of spring 1 is 17mm and wire dia of spring 2 is 19mm.

Then spring rate of spring 2 is spring rate of spring 1 X 19^4 / 17^4
ie. spring rate 1 X 1.56 or 56% stiffer.

Increasing number of active coils (n), reduces the spring rate. The spring rate is proportional to 1 / n.

Say rover spring 1 has 6 active coils and spring 2 has 8 active coils.

Then spring rate of spring 2 is spring rate of spring 1 X 6 / 8
ie. spring rate 1 X 0.75 or 75%

The difficulty of calculating an accurate spring rate for your unknown springs is to know the number of active coils.

Typically the coils at the ends are squashed together and the wire diameter is tapered to form a square seat for the spring (the terminology is squared and ground). These end coils are not active and it can be difficult to determine how many coils are active.

Spring rate is the load on the spring / the deflection of the spring. Usually given in lbs/inch or Newtons/mm.

So a 220 lb/in spring would need 220 lb to deflect it 1 inch.

the rules of thumb for the different spring ends are generally,

squared and ground -1.75 turns
plain ends -0.5 turns
plain ends ground -1.0 turns

this is usually pretty damn close for most calcs.

To add to what John has said, you add the total # of turns, then subtract 1.75 turns for your calc on Landy coils.

i don't think my brain can handle all those calculations, way to technical for me

i guess i will find out they sit if i ever fit them

phew

mate, give us an accurate wire diameter, ie. take it in a couple of spots, sans paint/powdercoat with an accurate vernier/dial caliper, the exact ID of the spring and an accurate (as close as you can tell) number of turns.