1963 rear leaf spring question

[Joseph W.]

I don't have a 1963 corvette, but I do have a rear 7 leaf spring for a 1963 car (supposedly).
I referenced my NCRS pocket spec guide book and see no reference for a F40/41 option.
Yet in virtually all listings for 7 leaf rear springs for sale, they list the year 1963-74.

I came across a big sale of Corvette parts from a long time corvette guy out of Carpinteria CA and he told me that 63 springs were one year only spring. And that the spring I was looking at was a 1963 spring.
It has 7 leafs, but the part where the spring leaves widen slightly from the end of the leaf is missing.
I compared it to an original F41 spring I have and the height and contour matches exactly.

Can anyone enlighten me on 1963 Corvette rear leaf springs and what is unique to them from other years?

Thank you

[Duke W.]

Re: 1963 rear leaf spring question

The base 1963 rear spring was nine-leaf with a constant rate of about 163 lbs/inch. This was a one year only spring as the base suspension '64 through '67 rear spring was variable rate. This spring is easy to identity as the leaves do not have constant curvature as do the '63 leaves.

The 1963 Z-06 Special Performance Equipment package included a seven-leaf constant rate 305 lb/in rear spring along with other HD suspension components. For 1964 all these HD suspension components were unbundled to a separate option, F-40, which carried over to 1965, and was restricted to certain engines like L-84 and L-78. For the L-78 all substituted HD suspension parts were the same the '63 Z-06 option, and L-78 with F-40 retained the 9/16" rear anti-roll bar that was standard on all big blocks through 1974.

These HD suspension parts that were substituted for base suspension parts, 1963 to 1974, are as follows:

1. 550 lb/in constant rate front springs.
2. 15/16" diameter front anti roll bar.
3. 305 lb/in constant rate seven leaf rear spring
4. Heavy duty front and rear shocks.
5. Heavy duty lower rear shock/strut mounts

The option number changed to F-41 in 1966, only available with L-72 (with reports of it appearing with L-36). Why the option number changed is unknown as the parts substitutions were the same as F-40 for the '65 L-78.

The bottom line is that the rear seven-leaf 305 lb/in rear spring that was introduced with the '63 Z-06 package continued as part of the F-40 and F-41 HD suspension options and the later ZR-1 and ZR-2 Special Performance Equipment packages.

For 1975 the option was changed to FE7 Gymkhana suspension, and the same parts were substituted except the front anti-roll bar. The front bar increased to 1 1/8" and a rear 7/16" bar was added. Of course this option was for small blocks only as the last year for the big block was 1974, and it was the first time in the C2/3 era that a small block Corvette was available with a rear anti-roll bar.

If you post a photo of the seven leaf spring you have, several on the TDB will likely be able to confirm if is is an original Corvette HD rear spring or an aftermarket spring.

Duke

[Joseph W.]

Re: 1963 rear leaf spring question

Thanks Duke
I will take a few pics and post it up tomorrow
Curious as to what I purchased.

[Joseph W.]

Re: 1963 rear leaf spring question

7E71244C-F2C9-4527-8173-DBD7E93DD466.jpg6269265C-644C-427B-9223-DCA04DE8F43C.jpg5BB198B1-EE0B-42BA-9940-E7BAF50334F0.jpg4E84E58C-B764-4D0B-B727-A01952A69569.jpg