1965 Leaf Spring Help

[brandosaac]

I am looking for some insight on a set of leaf springs I have.
I have owned a few sets of C4ZA-5556-S leaf springs and they have always been 3 main leafs and the 4th small one with the engineering number, for a total of 4 leafs.
The set in question are the same C4ZA-5556-S with a date of 137, but they have a 5th leaf (the second longest one was added in the pack) the one added is the one with the square end.

My questions are:
Do these look factory?,
Did Ford offer a tow package option for a 65FB K code or Shelby where they would have possibly added a leaf with a tow package??
Did the Competition R models have the same 4 leaf pack as the standard Shelbys and K codes? or could the R models have had an added leaf as std equipment

thank you in advance

[brandosaac]

more pics

[Bob Gaines]

I am looking for some insight on a set of leaf springs I have.
I have owned a few sets of C4ZA-5556-S leaf springs and they have always been 3 main leafs and the 4th small one with the engineering number, for a total of 4 leafs.
The set in question are the same C4ZA-5556-S with a date of 137, but they have a 5th leaf (the second longest one was added in the pack) the one added is the one with the square end.

My questions are:
Do these look factory?,
Did Ford offer a tow package option for a 65FB K code or Shelby where they would have possibly added a leaf with a tow package??
Did the Competition R models have the same 4 leaf pack as the standard Shelbys and K codes? or could the R models have had an added leaf as std equipment

thank you in advance

My guess is added by previous owner. I have not seen that on a original unmolested Shelby or R model.

[J_Speegle]

+1 Helper leaves added to increase the ratio.

Pretty typical in some circles decades ago

Larger clamps used also to make up for the increased thickness of the new stack of leaves

[KR500]

Not factory. The leaf spring band clamp is unlike any factory installed band I have ever seen, but is a Ford universal service part that they sold to fit many different applications with one part number.
Rodney

[OldGuy]

This set up looks exactly like one that I did on one of my early Mustangs many years ago (before one could buy "heavy duty" after-market springs) to increase the spring rate of the rear springs. I cut the "eyes" off a pair of extra main spring leafs and added them to the stack. The end result definitely added more weight carrying capacity and stiffened the ride of the car. I also had to add lowering blocks between the springs and the housing to get the car back down to an acceptable ride height.

[EdwardGT350]

what is the original spring rate and is there a source to buy original spec leaf springs?

[pbf777]

     Obviously, an "add-on" component from the after-market as it lacks proper engineering in the leafs' termination; adopting a simple (cheap) squared sheared profile, this concentrating the load transition and compounding the tendency for the upper leaf to break (fold) over the lower shorter leaf, and if aggravated may lead to its' breaking (separation). This vs. the as presented by the O.E.M. of a radius terminations thereby providing a more gradual ramping effect of the load applied by the lower onto the longer leaf above.  If the additional leaf extended beyond the supporting main spring eyelet turning up radius, then the squared sheared ending would be acceptable.       

     Scott.

[brandosaac]

thanks for all the info