Springs - Front

One of the most difficult codes to break are the front springs. That's because there were many different applications to match up as the pages (above) from the Master Parts Catalog will illustrate. Then on 2/14/66 Ford changed the applications; which spring went with which options. That being said, it doesn't appear that they changed the part number - load rating - paint marking system they were using. What they did change was which options a particular spring was used for. At this point I believe that the build sheet codes specified a certain spring part number, and since this remained unchanged, the code remained unchanged as well. Therefore, I have begun the following table. I'm sorry but I don't have enough build sheets yet to provide the codes for the Green or Violet colored springs.

Code	Part Number	Load	Markings
O	C5ZZ-5310-A	1279 lbs.	PINK
	C5ZZ-5310-B	1344 lbs.	GREEN
4	C5ZZ-5310-C	1490 lbs.	GRAY
	C5ZZ-5310-D	1413 lbs.	VIOLET
W	C5ZZ-5310-E	1491 lbs.	BROWN
X	C5ZZ-5310-F	1413 lbs.	RED

In order to verify the paint markings on your springs, it may be necessary to soak them in Evaporust. Above are some photos of a green 1344 lb. spring. It may be necessary to confirm the actual spring used in order to  verify what Ford installed. The MPC application table isn't enough of a guide; as Ford sometimes changed things for unknown reasons.

Springs - Rear

The rear springs came in four versions depending upon the body style and whether it came equipped with the increased rate Special Handling Package (SHP).

Rear springs can be identified by the part number stamping and paint dots or stripes. Below are some examples. The first picture shows the part number followed by 16  6E. It's currently believed that the (16) identifies the day of the year, in this case January 16th. And the (6E) identifies the year (6 being 1966) and the plant (E).

If you haven’t done anything to your leaf springs yet, try soaking them in Evaporust. It can be found at your car parts store. It will clean up the surface rust on the springs, and will enhance the paint markings.

Below is a table of information for rear springs:

Rear Springs – 4 leaf – 2-1/2” wide
Model	Load Rate	Spring Rate	Deflection	Markings	Build Sheet Code
Standard Coupe Part # C5ZZ-5560-C	610 lb.	85 lb.	7.176	C4ZA-5556-C-E-M-T (2) white dots/stripes	W
SHP Coupe Part # C5ZZ-5560-F	610 lb.	110 lb.	5.545	C4ZA 5556-H-J-R-V (2) red dots/stripes	Y
Standard Convertible & Fastback Part # C5ZZ-5560-D	650 lb.	85 lb.	7.647	C4ZA-5556-B-D-F-N-U (2) green dots/stripes	X
SHP Convertible & Fastback Part # C5ZZ-5560-E	650 lb.	110 lb.	5.909	C4ZA-5556-K-L-S-Y (1) green & (1) yellow dot/stripe	Z

Springs & Ride Height

If it's been awhile since my last post, it's because the codes and related information are getting a bit more difficult to decipher.

This post will begin a series on Springs. The build sheet had separate codes for the front and rear springs under a general heading named Springs on the second row, fifth column from the left. I'll discussed the front and rear springs in separate posts, but first would like to make an entry on the Ride Height.

The Ride Height is a function of the type of spring used and the weight of the vehicle it carries. Coupes, Fastbacks, and Convertibles were all treated a little differently because of the weight distribution of their particular body style. Options such as air conditioning, power steering, and the type of transmission also influenced the weight distribution, and as a result the load rating of the springs used. Therefore, there's a little bit of variability in the Ride Height of vehicles.

Following is a table of information provided by Mustang Concours Judge, Jeff Speegle. It was taken from a 1966 Technical Service Bulletin. It provides the measurements and a process for obtaining them. Remember, these dimensions were based upon the stock tire diameter of 25.3". In order to apply these measurements to your vehicle, it may be necessary to convert the measurements by factoring in your tire size.

You'll notice that the front of the vehicle originally sat a bit higher (approx. 1-1/2") than the rear.

TSB#727
Ride Height

Dated 4-1-66

To measure:

Place car on level surface. Push down on front and rear bumper by at least 1 inch then let off (to settle suspension). Measure at the center of the front and rear wheel wells - at the center of the wheel. Then lift up on the bumper and let settle and repeat process. Average both measurements. Do the front completely before doing the rear.

For tire sizes other than stock tires, calculate actual tire diameter. Subtract the stock diameter from the actual diameter (if the actual tires are larger in diameter). Divide this number by 2, and add the result to the tables below. If the actual tires are smaller, subtract the difference between the two tire sizes from the tables.

Front Ride Height
Model	Min.	Normal	Max.	Tire Size	Tire Diameter
6-Cylinder	25-27/32	26-13/32	27-13/32	6.95 x 14	25.3”
6 & 8 Cyl. w/ AC	25-3/4	26-19/64	27-19/64	6.95 x 14	25.3”
HiPo	25-3/64	25-19/32	26-19/32	6.95 x 14	25.3”

Rear Ride Height
Model	Min.	Normal	Max.	Tire Size	Tire Diameter
All except HiPo	24-1/2	25-17/64	26-17/64	6.95 x 14	25.3”
HiPo	24-7/64	24-55/64	26-19/32	6.95 x 14	25.3”