Front Coil Spring Clearance Problem

[JohnIL]

I've run into a weird clearance problem on my '65 C10. See the pictures below for a visual explanation.

Here's the scenario.

When I bought the truck, the PO had installed a set of LMC 2" drop coils on the front. Occasionally, whenever I unloaded the front suspension over uneven ground, I would hear one of the front springs twang. I assumed it was just because the springs are shorter than the originals.

Fast forward to today. I'm approaching the end of a power brake conversion project. While I had the front suspension apart, I did the common caster correction mod. I moved the lower control arms 3/4" forward to add more caster. As you would expect, this mod adds a minor angle to the springs. I had the truck back on the street for the first time tonight and the driver side front spring twangs every time I hit a pebble. With the truck back up on blocks, it's clear that the driver side front spring is making contact with the front edge of the upper spring pocket. The passenger side spring, however, is nicely centered in the upper spring cup, with about 3/8" of clearance.

You can see the difference in the pictures below. The first picture is the passenger side spring with plenty of clearance. The second picture is the driver side spring, clearly making contact with the front edge of the spring pocket. I verified that both springs are centered in the upper spring pocket and lower spring cup. I verified that that ends of the coils are seated in the indentions the lower spring cups. As far as I can tell, the springs are properly seated.

I thought maybe the driver side lower control arm might be further forward than the passenger side. I measured the position of the control arms from fixed points on the frame rails. They measure exactly the same.

So, I'm stumped. I would expect the springs to vary a little bit from side to side, but this seems pretty extreme. Is it possible the springs are that much different from each other?

I appreciate any wisdom you can share.

John