C2: When to replace rear spring

[Hans R.]

Is there a rule of thumb when it's time to replace the rear spring. I have a 1966 coupe with STD 9 leaf spring. Is there something that you can meassure or visualy check? Anyone have a good advice?
Hans Ryden #868

[Duke W.]

Re: C2: When to replace rear spring

If the spring is not severely corroded, it should still have its original design rate characterisitics and be okay for continued use.

Surface rust is not an issue, but pits or notches in the leaves can weaken the spring, cause it to loose rate, and eventually even break.

A careful visual inspection with the spring on the car is a starting point, however, to fully inspect the spring it should be removed, disassembled, and cleaned, and all leave surfaces carefully inspected, then reassembled with new liners if no major corrosion is noted.

Disassembly and cleaning the spring also affords an opportunity to apply a corrosion resistant coating (such as a good metal primer and enamel top coat) to all leaf surfaces, but this will likely result in a deduction if you have the car Flight judged.

As built, the springs had a grey paint applied to the tension (bottom) side of the leaves, only.

The most common cause of "spring sag" is actually compression of the rubber spring link cushions, and compressed cushions also significantly increase ride harshness. A "spring problem" can often be "fixed" by installing new cushions, and they should be replaced about every five years, even if the car is not driven as the continuous compression force on them continues to compress and harden them even when the car is sitting.

Duke

[William C.]

Re: C2: When to replace rear spring

If the lower (main) leaf has a curve in the upward direction from horizontal it needs help. A more precise method is to measure the chassis height from the ground on a flat surface using the method described in the Service manual

[Alan Drake]

Re: C2: Bottom Paint Only ?

I'm still talking about the rear spring not a boat.

At one time I understood that the entire spring was to be painted (may have misunderstood) Now my original spring did show signs that the top was also painted, however evidence on the top was only left around the center area. Also the edges showed remains of paint.

If only bottom is to be painted can I just remove the paint from the visible areas on the top? Assume top (that shows) needs to be bare metal?

Another question that I still have, the liners - does about 3/4" show past the leaf or cut flush?

[John H.]

Re: C2: Bottom Paint Only ?

Alan -

Full judging credit will result if the spring is fully-painted as described in the JG; the "real" paint process and appearance doesn't enjoy universal acceptance yet - maybe someday. The liners should be trimmed essentially flush with the ends of each leaf.

[Terry F.]

Re: C2: Bottom Paint Only ?

I believe there was considerable variability as to how the paint was applied to the rear spring. I have seen pictures of NOS and they looked painted all over to me and had considerable dripage. The one I saw was gray and the paint was chipping off in a lot of places. Terry

[Gary B.]

Terry: I agree 100% with your assessment

I have a GM NOS F41 spring and it definitely has paint on tbe edges and slobbered on the compression side as well as mroe complete converage on the tension side. It is not a neat and pretty thing by any stretch of the imagination.

Gary

[Terry F.]

Wow, I said something someone else agrees with! *NM*

[Gary B.]

Terry: A good day to buy a lottery ticket. *NM*

[Wayne M.]

Paint / Liner Extension

FWIW, here's an early '65 spring; top view. The only grey paint (?) was what oozed out between the center bolt hole (probably) as the spring assembly was being sandwiched via the bolt torquing. No grey paint anywhere else on top surface.

The bottom is a much different story. Same situation on a late '65 spring that I have apart.

Also, the spring in the pic had plastic liners that extended about 3/16" beyond the edge of the leaf above. So that's the way I cut the new liners. Also, a mid-production '64 spring (which is not apart and never has been) also has 3/16" liner extension. No sign of grey paint on upper leaf ends on this one, either.

[Barbara S.]

Re: C2: When to replace rear spring

Hans. I have a 67 Coupe. When I bought my car, it seemed a bit low in the rear of the car. When I restored it, I replaced all of the rubber cushions and it made a difference. You weren't specific why you were asking about the change out of your springs. If the metal is good and not bowing the wrong direction, maybe you just need to change the rubber cushions? It made a difference for me.

Good luck.
Tony

[Dick W.]

Re: Paint / Liner Extension

Wayne, your spring is typical of what it should look like if the line employees followed the specs. Protective coating on one side only. Would run out and cover the sides.

Franz Estericher has the all the prints and manufacturing specifications covering the springs and other suspension components.

[Gary B.]

The key phrase is...

Dick,

I think the key phrase is: "if the line employees followed the specs". The NOS F41 spring I have clearly shows the edges completely covered with paint, which is not according to the spec on the GM engineering drawings.

Gary

[Dick W.]

Re: The key phrase is...

Franz told me last year that a heavy coat would be applied and it would run down the edges. I believe that it was rolled??

[Gary B.]

Could have been rolled

Dick,

I can believe it was rolled, with no apparent worries on how sloppy it was done.

Gary