Help me confirm the new width of my frame spring mounts

Aug 15, 2005
Lemoore, CA (south of Fresno) / Cortes Island, B.C
I'm installing a 60 series axle in my 40. Before I start to tack the spring hangers in place (need to widen my springs) to mock it up before full weld, I wanted to run my logic for moving my frame hangers.

I took the old axle and measured the width between the center holes in spring perches. I then measured the width between the 60's center hole spring perches. The difference between the 60 series spring perch’s center holes was 2.5" wider than the 40 series axle’s center holes.

In order to move (widen) my stock frame mounts for the springs, I need to divide that distance by 2 and will need to move all my frame mounts out 1.25".

Is my logic off here? I know that the 60 series axle is about 3"s wider, but the important measurement is from where the old springs sat on the axle and frame to where they will sit on the new axle.

Unless the 60 series axle spring perches is off in relation to the 40 series axle, I should be good to go. With my luck, I will tack everything in place to find out, after measureing the distance from the frame to the knuckles, the axle has one of the perches off a bit.
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