Posted by Charlie on June 12, 1999 at 00:07:28:
In Reply to: Leaf Springs posted by Ken on June 11, 1999 at 07:33:19:
I had Alaska Spring build me a pair of fronts with 6 leaves of 0.320" to replace 11 leaves of 0.260". It's 20% softer but still too stiff. To match my M37 fronts (which are bit overloaded with the winch, diesel, Clark 5spd, pto, hydraulic pump and hyd. reservoir) I'd need to go down to 4 leaves. I may simply remove the bottom leaf which would get it down to 400-420 lbs/in down from 600 lbs/in originally with the HD fronts. You must of course ask the spring maker to build in more arch to compensate. My rears are 10 leaves of 0.350" replacing 14 of 0.320". Overloads of 5 X 0.320" replacing 6 X 0.260", actually 25% stiffer.
The rule of leaf spring stiffness: Proportional to 1st power of width, 2nd power of stiffness, inverse 3rd power of length.
When calculating "sprung weight" for purposes of specifying unloaded free arch, be sure to subtract ~500 lbs per end for weight of axle and wheels/tires.
Source: Machinery's Handbook 25th Ed., pp. 234-235, "Stresses and deflections in beams", case 2.
Charlie