69 rear spring question

[Greg L.]

My original rear spring is sagging and needs help but to preserve the originality of my car I would like to save it by having it re-arched. Is this a good idea or will it just sag again in a short time. If replacement is the only good option, does anyone make a correct reproduction or are they all just service replacements out there? Oh ya, it's a standard 9 leaf.

[Dick W.]

Re: 69 rear spring question

Having it re-arched is a very good idea. Find a good spring shop in your area and have it re-arched to original specifications. If you do not have a shop in your area, there was a thread sometime back about a company, Eaton Detroit Springs, that does the re-arching

[john lokay]

Re: 69 rear spring question

I spoke with Eaton Detroit Spring this past summer about having the rear spring from my 66' re-arched and they advised against it, stating that it would weaken the spring. I wound up buying a new spring. If you want to call them to discuss, their number is 313 963-3839.

[Dick W.]

Re: 69 rear spring question

Over the years I have had 100's of springs re-arched. They always took them apart, heated them cherry red in a forge, oil quenched, and then hammer arched them back to the original arch. It makes me wonder what has changed. Here is a spring that carries less than 2,000# and it weakens it? Some of the springs that I had done carried 22,000# + per side.

[Duke W.]

Re: 69 rear spring question

There are many discussions in the archives on this subject with differences of opinion. Here's mine.

The most common cause of rear ride height loss is compressed spring link cushions. As they compress and harden they also dramatically increase rear ride harshness, so my first question is how old are yours?

On average they should probably be replaced every five years regardless of mileage. I consider them to be a maintenance item. A set of eight costs about ten bucks and they take less than an hour to replace.

Leaf springs normally retain their shape/rate unless they are significantly or severely corroded. Re-arching may only be a temporary fix, and since no one has the specific arch dimensions or heat treat process used by the OEM, re-arching in the field is going to have mixed results and anecdotal evidence supports this.

My recommendation would be to replace the spring link cushions and verify that your link bolts are correct. If this doesn't solve the problem, remove the spring, disassemble it, and give it a thorough inspection. If any leaves have signficant corrosion damage, you might be able to find used, serviceable replacement leaves. I also recommend treating the spring to a good corrosion preventative finish. Though not OE "correct" it should arrest further corrosion.

Reassemble the spring with new liners and reinstall it with the new cushions. If the ride height is still low, and you are certain that the proper length link bolts are installed, they can be shimmed to raise ride height.

Duke

[John H.]

Re: 69 rear spring question

I have an Eaton-Detroit reproduction 9-leaf spring on my '67, installed about a year ago; I had them leave it unpainted, then I cleaned it up, painted it with the Quanta spring paint and installed the Quanta liners, and it looks great. The leaf ends are tapered and "curled", and looks very close to the original. Ride height was about an inch too high after installation, but after a few hundred miles, the "D" height was in spec and the car now sits dead level.

[Greg L.]

Re: 69 rear spring question

Thanks for your thoughts guys. I think I'll take it apart to check for corrosion but I'm pretty sure it is shot. My spring cushions are also shot but my main concern was that before the body came off, the weight of the car did cause the spring to sag(each end turned up slightly) and I thought that the bottom of the spring should be more or less straight...correct? I'll talk to some local spring shops and see what they say.

[Joe L.]

Re: 69 rear spring question

Greg------

I've looked at quite a few 63-79 Corvette rear suspensions over the years. So far, I've yet to see a single one that actually "sagged" in the middle. Usually, when the car is observed with the suspension normalized (i.e. at ride height) and the spare tire carrier removed for easy "eye-balling", the spring appears "flat" or with an almost imperceptible "rise" at the center. Either one indicates a spring that is fine for re-use. I have NEVER seen one that had a noticeable "rise" at the center, although this is what most folks expect to see or they figure their spring is shot.

Absent significant corrosion of the spring leaves, the springs are usually fine for re-use after rebuilding. Rebuilding involves cleaning all of the leaves of surface rust, etc., coating the tension surface (or, the whole of each spring leaf if you want to ensure complete rust protection) with Ionoklad as available from Quanta, installing new spring leaf insulators, and installing a new center bolt. Usually, this results in a spring as good as new or nearly as good as new.

[Greg L.]

Re: 69 rear spring question

Thanks for your input Joe. Maybe I shouldn't say it is sagged because, with the weight on it the majority of it is flat across the bottom, except for about a foot or so from each end where it has a noticable "curling up-ward". Not sure if you know much about archery but it sort of looks like a recurve bow. Maybe I could get away with just re-arching the bottom two leafs. What do you think?

[Gary B.]

One option is to replace just the main leaf

Greg,

Failure of the main leaf is the one thing that will certainly ruin your day. If your main leaf is indeed past saving, my suggesting is to replace just the main leaf with a repro main leaf from Eaton Detroit Spring. Mike Eaton might let you purchase just the main leaf and, if so, that will certainly save you some shipping costs. Mike can and will re-arch your leaves if you really want it done and Eaton is one place that I believe can do the re-arching correctly. Even if you choose not to re-arch, you still might consider replacing the main leaf as I outlined in my Restorer article from a few years ago.

Gary

[Dick W.]

Re: One option is to replace just the main leaf

I believe that Gary has a very sound recommendation. I would at least replace the main leaf. If you break a main leaf you will most certainly have a bad, if not very bad, day. Close kin to a "quick fall-off" wheel coming off. If you break anotherleaf, you just lose carrying capacity, not alignment of the rear control arm

[Greg L.]

Re: One option is to replace just the main leaf

Actually I just got an e-mail back from Eaton-Detoit...$100.00 for the main leaf. I'll check my other leafs and if they look okay, I'll probably go this route. What do you all think?