Re-Installing 1960 Leaf Springs

[Joe M.]

Prior to removing my original leaf springs in the winter of 2010, I did not measure the distance from the top of the axle tube to the underside of the frame "kickup." GM listed 6 inches with body on, but no passengers. I have no way now to determine how worn out they really were.

I am almost finished with cosmetic restoration without re-arching and considering re-installing one side only as a test case. I am not a structural engineer, but I doubt if the tensile strength of my leaf springs today is the same as it was when they were new in December 1959.

Can 52 year old leaf springs still have tensile strength that is similar to when they were new? I can't define "similar."

[Thomas H.]

Re: Re-Installing 1960 Leaf Springs

Joe,

Just last night I was doing some ride height measurements on my 60 and could not find anything that mentioned the rear ride height in the AIM. My C3 had several ride height measurements in the AIM, not this one.

Where did you find reference to the 6" number? I rebuilt my original springs and I'll make that measurement tonight and post the results.

Tom

[Joe M.]

Re: Re-Installing 1960 Leaf Springs

A.I.M. Section 3, Sheet 4.00, View C, Rear Dimension B = 5.3 inches (theoretical measurement) with full tank of gas, but no people; or 4.49 inches with 2-150 pound people (actual design load condition).

[Gary C.]

Re: Re-Installing 1960 Leaf Springs

Joe,

Can you scan and post as I don't have a '60 AIM?

The only measurement in the '57 AIM Section 3 sheet 4 from top of the rear axle to the underside of the frame = 3.8" curb weight.

Thanks,

Gary
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[Dick W.]

Re: Re-Installing 1960 Leaf Springs

Typically springs that have the load removed with regain most, if not, their original arch. When reinstalled they will measure close +/- of original, but will eventually sag back to the previous installed measurements.

Old Indian Trick. If your cars sags, jack the car up and store it on jackstands. I have seen cars "grow" ground clearance by doing that and nothing else.

[Joe M.]

Re-Installing 1960 Leaf Springs

The AIM page is attached ( I think).

The only way I will answer my own question is to remove the aftermarket spring set on one side and replace with original spring set and measure Dimension B; then decide if I can live with the result.original spring sag.

If anyone has another trick for flattening the leaf springs so that the shackles line up with the holes, please let me know. I found a historical Restorer article on the subject.

[Joe M.]

Re: Re-Installing 1960 Leaf Springs

The attachment showed that it uploaded, but I don't see it in the previous response. i had to reduce file size. Now it is attached.

[Paul J.]

Re: Re-Installing 1960 Leaf Springs

Can 52 year old leaf springs still have tensile strength that is similar to when they were new? I can't define "similar."

The short answer is "yes". Springs had a tensile specification, and old springs can still be within that. However, this does'nt correlate to ride height by itself. It is the arch that you are interested in first, as it sets the ride height for your particular car. If the arch is OK then the tensile strenght is what holds the arch under load, and also determines your ride height. Springs were hardened, but they go through cycles of flexing which can cause strain hardening in some areas, but weaken others. As you know, the end result can be "sagging", and that's what you want to know.

[Joe M.]

Re-Installing 1960 Leaf Springs

The arch dimension is still the same as it was originally, but that is not going to tell me anything with them off the car. I will have to re-install to find out how much tensile strength they have lost and if it is acceptable to me. Not looking forward to the job, but want to know the answer. First thing I have to do is wait until my garage is not 93 - 97 degrees every day and night. That should be another month away!

[Gary C.]

Re: Re-Installing 1960 Leaf Springs

Joe,

Thanks. Same measurement location - different measurement from '57.

Gary
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[Thomas H.]

Re: Re-Installing 1960 Leaf Springs

Joe,

I got to measure mine this evening and I'm getting 6.5" on the drivers side and 6.75" on the passenger side. Right now, the car has no gas, oil or coolant in it. I'm hoping to get the car running on Sunday (first time since 1985). I expect it will come down a bit more once the fluids are in.

Interesting thing is that I thought it was sitting a bit low in the rear, but according to the dimensions, it is about 1" high right now.

Tom

[Paul J.]

Re: Re-Installing 1960 Leaf Springs

The arch dimension is still the same as it was originally, but that is not going to tell me anything with them off the car. I will have to re-install to find out how much tensile strength they have lost and if it is acceptable to me. Not looking forward to the job, but want to know the answer. First thing I have to do is wait until my garage is not 93 - 97 degrees every day and night. That should be another month away!

Joe, you can get an idea of the tensile strength by putting weight on the leaves individually. Turn each leaf over and put a known weight on it and measure the deflection. You don't need to know the actual spring strength, just the amount of deflection. This method was discussed in this forum some time back (I'm too lazy to look it up right now) but unfortunately I think it was for a C2. If you can find someone who has done this and can give you the deflection for a specific weight, you can find out if your spring is OK while it's still off of the car.

Paul

P.S. I can relate to the garage temps. We had some 100+ degree days two weeks ago, and I was under a Honda changing the timing belt. If it had not been for the high ceilings in the shop and the box fan beside of me, I would have melted.