Jump to content

Cutting Springs: Rate per coil calculation


Recommended Posts

Maybe someone's already done this but I couldn't find it. I was curious how much the spring rate increased with the amount of coil removed.

 

According to the Blue Book, the spring wire diameter and spring OD is the same, front and rear, for 1502, 1602, 1802, 2002, 2002ti, & 2002tii

With that information all you need to do is count the amount of active coils you have to figure out rate:

 

image.png

 

(* ignore "front" in the above pic. This is the same for the front & rear.)

 

I.E. - My 1975 2002 had 6 active coils in front, stock. I cut 1.5 coils so the front rate went from 120.7 in/lbs to 161 in/lbs. 

 

...of course this is all in a perfect world where deterioration doesn't exist and all materials are identical, but hey, it's a ballpark. 

________________________________________________________

 

Formula:  in/lbs = Gd^4 / (8ND^3)

 

d = wire size (inches)
D = Mean Diameter (inches)
N = Number of active coils
G = Shear Modulus of Material

 

d = .465"

Spring outer diameter = 4.992"
D = 4.527"
N = 6 (front on my '75 2002)
G = 11,500,000 (Oil Tempered MB - ASTM A229 gen. purpose spring steel) 
 

 

(Calculator here: https://www.engineersedge.com/calculators/comp_spring_k_pop.htm)

 

Dimensions from the Blue Book:

 

 

image.png

image.png

 

 

 

 

Edited by Mucci
duplicate images
  • Like 4
Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.



×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.