Outer Limits 4x4 Board

Hi , well im finishing the details of my suspension , but everything i try seems to not to be correct , so after HOURS trying to figure out what's the REAL spring rate equations , i started looking for help.. so here we go:

1st) What's the spring rate equation for the normal leaf springs application, i mean those that form a parabolic path (3rd leaf = half of 2nd , 4th half of 3rd) etc

2nd) what's the spring rate for a Quarter Elliptic setup?

i've these ones, but they seems not to be correct in any way ,

for normal semi-eliptic => ((b*n)/12) * (1000*h/L)^3

for QE : a really weird => 293943 *b*n*(h/L)^3

where h=height of the leaf , b=width L=length from eye to eye , all in inches , n number of leaves

PLEASE help.... i cant finish my damnly late proyect without this info..

Thanks a lot!
Plafo

Writting from Very very far....

Try and get hold of a book called the "Leaf Spring Design Manual" by the "Society of Automotive Engineers". It has all the equations you want for any possible spring application. If you are in Brisbane you can go to Uni of QLD library and photocopy the bits you need from it.

Sorry I don't have the equations off the top of my head.

We have built these setups on both of my previous Zooks the first one was way to soft.We used Pajero leaves.
Second time around we use rear IFS hilux springs. But as you cut the spring in half we used the cut off load leaf and second leave on top of the rest. This was a lot better and made the truck heaps stable.
The rate was very stiff standing on the back of the buggy it would hardly move at all.
The buggie weighed around the 800kg mark.
SAM

ISUZUROVER wrote:Try and get hold of a book called the "Leaf Spring Design Manual" by the "Society of Automotive Engineers". It has all the equations you want for any possible spring application. If you are in Brisbane you can go to Uni of QLD library and photocopy the bits you need from it.

Sorry I don't have the equations off the top of my head.

Hey thanks a lot anyway , but Im in CHILE , i'll take a look at the university , in this case the web isnt a good resource...

just another question , what are NORMAL spring rates? i used to belive that for example , 250 lb/in for a Hilux is normal... or not?

Greetings!
Plafo