[Sport69]

I know it's been a few years since I addressed this issue but it's still there, and I finally made my way back to it. A couple things I did do was to get rid of the shock extensions and remove one short leaf in the springs, it didn't make much difference at all. I also changed the KYB Gas adjust shocks to the stock version, again, no difference. I did notice while I had the shocks removed to switch them, I pushed down on the rear of the car and still had very little travel, this would seem to point directly at the leaf springs, what do you all think? I'm thinking I need to swap the set that's on there out for an original, less stiff, set, any suggestions?

[Sport69]

I just found the picture I took before I cleaned and painted the springs that were on the car when I bought it, seems like they may be made for a truck, or a heavy duty/performance application (660 lb. load capacity/5-leaf) and wrong for my car.

Here's the number off the leaf spring, S&G21-339-42, and here's the info I found matching that number:
Product Specs for Leaf Springs 21-339
Length (A): 25 Inches
Length (B):31 Inches
Width:2-1/2 Inches
Location:Rear
Number of Leaves:5
SRI Number:21-339
OEM Number:337230
Arc (C):7-1/4 Inches
Pack Thickness (D):1-3/8 Inches
Capacity:660 lbs.
Front Bushing:Included / RB-95
Rear Bushing:None - Berlin 1-5/8" Eye
Spring Construction:2/291 3/262
Note:1-5/8" eye uses (2) HB-1000 bushings; Order separately
MPN: 21-339

[rohrt]

660 lbs must be the load capacity not the spring rate.

A little google search
Stock leafs are 125 lbs/inch, Hotchkiss are 150-180 Variable Rate. 68 Z28 rear "BR" springs have a 135 lb rate, and a 690 lb load.

Loosen your leaf shackles completely and see if you are able to get some movement in the rear.

[Sport69]

Yes it is.

[Sport69]

Put the new 4-leaf leaf springs on and it solved the problem. It now rides like it's should, the car absorbs the shock, not me.
Like a friend of mine said, who had the same issue, I could've run over a dime and told you if it was heads or tails, lol.

[JEC3039]

Sport - what spring brand and part number did you buy?

[Sport69]

Part #3932719. I got them from a local spring shop (Penn Public in Altoona, Pa), not sure of the brand.