C1 Free Arc measurement

[Keith T.]

I recently had my rear leaf springs re-arched by Eaton Detroit springs. Before I sent them out, I was told by a few C1 owners that the free arc should be 5-1/4 inches. However, in talking to the rep at Eaton, he told me the blue print for 53-57s called for a 3-5/8 inch arc, which I went with. The 58-62 showed the 5-1/4 inch. Installed, the ride height on my car is good with the 3-5/8 inch arc.

My question is, why is the free arc different between the 53-57s compared with the 58-62s. I was under the impression the frame and suspension were essentially identical for these model years.

[Richard M.]

Re: C1 Free Arc measurement

Keith, Just a guess but I'd think the added weight of those huge rear bumpers and trunk irons on the '58's may have prompted Engineering to increase the arc. Then in '59, after dropping the trunk spears, with the added axle strut bars then later in '60 with the rear sway bar, decided to not change the arc spec back.

Admittedly all speculation, but to me it may have been why.

Rich

[Keith T.]

Re: C1 Free Arc measurement

Thanks, that makes sense. I was just curious, because I was told by some to set the arc at 5-1/4, but went with Eaton's suggestion of 3-5/8s. There obviously is a reason for the difference.