C3: Rear spring restoration

[Rob M.]

Hi all,

Another question on my first bits of restoration of our C3 '69 car:

I've ordered a new rear spring from Eaton which arived last Friday. But when I compare the spring with my original one I noticed the stack of leafs (incl. the liners) is appr. 3/8" thicker than the original (2" for the original versus 2"3/8' for the repro). It seems like the individual leafs are slightly thicker.

Did anyone else had this happening in the past? I persume I could just you slightly larger bolts to mount it all in place but I can't figure out why they not simply using the same dimensions leafs...

greetings,
Rob.

[Gary B.]

C3: Rear spring restoration

Rob,

Is your spring a 9-leaf or a 7-leaf? Can you measure the thickness of each leaf? When I wrote one of my articles on leaf springs for the Restorer I had a chance to inspect an Eaton repro spring and at that time the leaves (at least leaves 1-3) were thicker than the original GM leaves 1-3 and the resulting assembled repro spring was approx. 0.30" thicker than my orginal assembled spring. In the past year or so, I heard that it was possible to request a spring from Eaton that used spring stock of the same thickness as was used by GM. This is second hand information, but if true, maybe you got the spring made from the thicker stock, like what I inspected in 2000.

Gary

[Thomas S.]

Re: C3: Rear spring restoration

Rob:

I went through the rear leaf spring nightmare about 3-4 years ago. I own a C2, and if I recall, the 9-leaf spring is the same as in the C3. I too bought it from Eaton. I first was sent a single stage with leaves that were too thin. When I returned that one, I was given a two-stage with leaves that were too thick. While it had the correct arch, it made my car ride about 3-4 inches too high. When I approached Eaton on this problem, they finally admitted that they could not get the correct thickness of steel. Eaton took about 3 inches of arch out of the spring for me and the ride height is about correct. Since then, I have heard rumors that they have obtained the correct thickness of steel, but I don't know if it is true, so it may depend on how long ago you ordered the spring. I ran across Gary Beaupreau's excellent articles in "The Restorer" and spent some time on line discussing the issue with Gary. If you haven't read his two articles, I highly recommend you do before going further. I purchased an original used spring and plan on rebuilding it based on Gary's article.

Tom

[Rob C.]

Re: C3: Rear spring restoration

Hi Rob,
I allso bought one for my 72 wich was a 9 leaf. I just stripped off all the black junk and will put the last cote of paint on it tomorrow. I hope when I put it togather I dont have the same problem. Time will tell.
Rob

[Rob M.]

Re: C3: Rear spring restoration

Hi Gary,

It is a 9 leaf spring. I'll compare the thickness of each spring leaf tonight and compare it with the original.

I'm currently in the middle of the process of dis-assembling the spring. cleaning each leaf (since the liners are melted a bit on each leaf) and spraying them zinc gry.

I'll let you know the result...

thanks for your reply,
Rob.

[Rob M.]

Re: C3: Rear spring restoration

Rob,

let me know your findings. I'm a bit reluctant to send it back (all the way from the Netherlands to the States considering the shipping costs and tax duty problems). But I'm a bit disappointed with the result, considering I bought it from Eaton because I thought they should be able to make the best repro...

I hope it won't show that much when mounted, I still think it is a good decision to replace the old, weak spring from a safety perspective though...

greetings,
Rob.

[Rob M.]

Re: C3: Rear spring restoration

PS what should the correct thickness of the pack of leafs and liner should be?

[Gary B.]

Assembled thickness

Rob,

The GM spec on the assembled thickness of the '64-'74 two-stage, 9-leaf spring is 2.121"

Gary

[Rob C.]

Re: C3: Rear spring restoration

Rob I put my spring togather tonight and the spring was a total of 2and 9/16th thick. I donot think that is good.
Rob