Topic: Spring Rate ?

[Brian Conway]

     Looking around for a resource or a reference for information on the spring rates.  The leafs on my 65 are stamped C4ZA 5556 and the leafs on my 69 are stamped C9ZA-5556-G.  The front springs carry no ID at all.  The different body styles and different suspensions had different spring rates/loads ?  How to find out what these were ?  So far; MUSTANG Recognition Guide-Dobbs, Farr, Heasley and Kopec 1989 pg. 80 and MUSTANG 64.5-73 Restoration Guide Corcoran and Davis 1998 pg. 261.  Not much there. 
     On the 65; does the yellow belong there ?  Any help with the ID ?  Thanks,  Brian

[jwc66k]

Brian,
  The only place I know where any spring rates are displayed is Ford Car Parts. It's on the line for the replacement spring for a specific year, model and options. The dash letter for your rear springs should be stamped in a third line. Mine are very faint, so clean up that area and look again. Fronts are not marked but identified by color stripe or a label/tag for service. They probably came to the assembly plants in a big wooden box with an ID on the box. In the box, they were all the same. Faithful minions painted stripes for assembly line ID.
Jim

[WT8095]

The MPCs show rated load ("load rate"). Not the same as spring rate, but can be used for comparison.

[Brian Conway]

Thanks Jim.  On line search's are fruitless, never ending and frustrating.  The other leaf spring stamps seem to be 1  3  and E5.  The E5 is a date ?  The 1 and 3 who knows. Was thinking the yellowish stain might suggest something ?   Brian

[WT8095]

Look really closely, I think I imagine I see a faint ghost of a "K".

"13E5" is the 13th day of 1965.

[J_Speegle]

Thanks Jim.  On line search's are fruitless, never ending and frustrating.  The other leaf spring stamps seem to be 1  3  and E5.  The E5 is a date ?  The 1 and 3 who knows.

Current understanding is that 1 3 E5 decodes into 13th day of 1965 and the E identifies the supplier/plant

Originally these were measured by deflection. A specific weight is applied to the center of the spring and the amount of compression was measured according to one of the engineers 

The MPC grouped together similar springs in groups with similar rates to cut down on need to inventory all the different original rates and springs

[Brian Conway]

Thanks guys.  Dave if you see a ' K ' I 'am on board with that.  In any event the rate is either 610 or 650 and no special call out for a GT ?  Interesting about lumping them all together.  So not all that highly fine tuned as the different load and rate numbers would suggest ?  About the supplier code letter ' E '  everything back there is May.  Pinion support, diff case, axle tag and, I thought, leaf springs.  Coincidental ?  Brian   

[WT8095]

...no special call out for a GT ?  Interesting about lumping them all together.  So not all that highly fine tuned as the different load and rate numbers would suggest?

Maybe not, but keep in mind that the MPC shows service parts, and as Jeff explained the service parts could be on a "close enough" basis. For example, the C5ZZ-D is listed as replacement for five separate original part numbers. There's nothing in the MPC to explain if those five were all designed with the same load rating, or if they were each slightly different.

And don't read too much into me seeing a "K"     That's a long shot, but that's the spot the suffix should be, so a different lighting angle or some careful cleaning may reveal what's really there, if it hasn't succumbed to corrosion.

[sgl66]

This may help answer your question http://mustangcodex.blogspot.com/2011_06_01_archive.html

A friend who owns a spring shop referred me to this last year to cross reference replacement numbers...if you're thinking of going down that road. http://www.springresearch.org/PDF/volume_16.pdf

If you want to see a different year, change the volume # at the end of the URL

[J_Speegle]

...........  About the supplier code letter ' E '  everything back there is May.  Pinion support, diff case, axle tag and, I thought, leaf springs.  Coincidental ?  Brian

Coincidental - have dozens of spring pictures (likely allot more   All with E's With the day of the year called out in the 2 or 300's its not going to decode as  may

No "special call out" for GT since it was easier for the parts guys to look up the markings on the springs your replacing to see what they carried in stock (current, at that time, replacements) Plus its allot more hassle to figure out from a trim package on a used car. After a few years thee were likely allot more GT's than they had built originally so those springs would not match (normally) the original springs installed on GT' s

For those look for the -S

[WT8095]

Just ran across a source I forgot about. The AMA Specifications sheets list actual spring rates for various engine and suspension combinations. For example, the 1968 sheets list the following for 390-4V engine:

Front springs: 260lb/in (115lb/in at wheel) - 320lb/in with GT package
Rear springs: 85lb/in (110lb/in at wheel) - 115lb/in with GT package

Also lists spring dimensions, SAE steel grade used, and other technical details. These sheets go into great detail on many other parts of the car - want to know the depth of the piston ring grooves? Distributor advance in degrees at a given amount of vacuum? How many revolutions/mile for F70-14 WSW tires? It's in there.

The copy I have has a revised date of 4/15/68, and includes data for 428CJs. As much detail as it goes into, I would take the information with a grain of salt. It may not reflect running changes or combinations of options that aren't listed.

[Toploader]

And yet another source for the 65s. Go to page 22. Both front and rear included.

http://www.mustangtek.com/Library2/MustangaCompleteGuide.html

[WT8095]

And yet another source for the 65s. Go to page 22. Both front and rear included.

http://www.mustangtek.com/Library2/MustangaCompleteGuide.html

Looks like they reprinted a small portion of the '65 AMA Specifications. Interesting guide!