1968 Original Rear Spring Restoration

[William H.]

This winter I am going to rebuild the rear suspension and differential on my 427 '68. Everything is original. What is your recommendation on the rear springs? The car has 65000 miles and sits drivers side low. Does anyone rebuild them or should I replace or leave alone? Also, any recommendations on refinishing the half and drive shafts? Is this something I can do myself? Thanks for your suggestions. Bill

[Jack H.]

Re: 1968 Original Rear Spring Restoration

On the rear spring, to my knowledge there is SOME level of detectable difference between todays' replacement/reproduction parts and what was factory original to your car. IF the original is in good condition (not eaten into by rust AND not overstressed), it's simply a matter of cleaning it up, adding fresh paint, new liners and reinstalling it. But, especially on BB or hi performance SB cars that have gone through multiple owner hands, the spring might not be a good candidate (driven hard, overstressed and fatigued).

If that's the case, you're on the horns of a dilemma. Some have had good luck with having their original springs re-arched. But, others have experienced failure. By this I mean the spring was re-arched, but very quickly reverted to its worn out geometry upon re-installation and use. So, it can be a crap shoot here. If there's a competent suspension shop in your neck of the woods (one who has time/experience on their side and DOES re-arch springs), get their opinion once you have your original spring off the car.

How to tell if your spring is in 'spec' once you get it off? Shake it and lay it on the garage floor on its side. Lay a straight edge across the bottom connecting the center lines of the two end point mounting holes. Now measure the springs' "free arch". That's the distance from the mid-point of the connecting straight edge up to the bottom center surface of the spring.

A standard 9-leaf spring should exhibit about 10.0 inches of free arch. The optional high performance 7-leaf spring should show roughly 6.25 inches of free arch.

[Steve L.]

Re: 1968 Original Rear Spring Restoration

This was extensively covered back in Apr 2010 by myself and Gary Beaupre,. We showed how you could actually measure the forces on each leaf using only household scales and a few other simple items and showed some numbers you can use as a guide. Have a look:

https://www.forums.ncrs.org/showthread.php?77439-Rear-Leaf-spring-force-measurement

[Erik S.]

Re: 1968 Original Rear Spring Restoration

I have good experiences with rebuilding / rearching my original L46 spring for my 69. Done by Werner Meier's shop in MI

[William H.]

Re: 1968 Original Rear Spring Restoration

Thanks for everyone's ideas.