'63 rear leaf spring combinations?

['63split]

Hello,

I recently purchased a '63 coupe. I'm now in the process of a frame on restoration. While under the car during gas tank replacement I noticed that there are 8 leaf springs mounted and not the 7 or 9 springs that I've read about here on other forum threads. Was there an eight leaf option available from GM or aftermarket source?

Thanks,
Mike

[JohnZ]

No GM option - all 63's had a 9-leaf rear spring (#3794095, 192#/inch rate); the first three leaves (from the bottom) were .214" thick, and the other six were .194" thick; all were 2-1/4" wide, and the top three were flat - there were no bands of any kind on the spring.

The '64-'67 9-leaf rear spring (#3850839, 196 #/inch rate) was identical, except the bottom (main) leaf was 2.24" shorter in overall length (which increased the spring's rate slightly).

[WayneC]

Actually, John, the original 9-leaf 63 rear spring did not have the 3 flat leaves... all were curved. I think 64 was the start of the flat leaves. I have a May-build '63 that I know was original and it had all curved leaves.

I agree that an 8-leaf spring is not an original, except of course that someone could have removed a leaf.

I'm curious, though... wouldn't a shorter main leaf have screwed up the geometry of the end hanger bolts?

['63split]

I'm not sure what has been done to the springs. It looks stock and everything fits well, but there are only 8 springs in the stack.

Thanks,
Mike

[JohnZ]

Originally posted by WayneC
Actually, John, the original 9-leaf 63 rear spring did not have the 3 flat leaves... all were curved. I think 64 was the start of the flat leaves. I have a May-build '63 that I know was original and it had all curved leaves.I'm curious, though... wouldn't a shorter main leaf have screwed up the geometry of the end hanger bolts?

Yup, should have clarified that - the '63 (only) spring had all nine leaves curved; from '64-up the top three leaves were flat, but were the same overall length end-to-end as the curved '63 leaves.

The bottom leaf was shortened 1" per side for '64-up to increase clearance to the tire inner sidewall. The angle from vertical of the link bolts isn't that critical, as the dynamic geometry of the rear suspension is established by the half-shaft and camber strut rod acting as the upper and lower control arms; the link bolts just support the load, independent of the geometry.