Tampa Spring Company

Heavy duty truck and trailer suspension parts and repairs.


Three ways to identify a Leaf Spring

The following information details the three ways in which a leaf spring may be identified for a specific application. These methods are listed in order of difficulty, therefore always attempt to identify by O.E.M. part number first before using identification by model or spring dimensions. In many cases the spring may be identified without the need for any measurements.


Identification by O.E.M. part number


The following information details the three ways in which a leaf spring may be identified for a specific application. These methods are listed in order of difficulty, therefore always attempt to identify by O.E.M. part number first before using identification by model or spring dimensions. In many cases the spring may be identified without the need for any measurements.


How can the O.E.M part number be obtained? Use one of the following methods:


1. Call the local dealer with the vehicle serial number

2. Truck-build sheet (line setting sheet) will often list the front or rear spring

3. Check the spring for a stamping number as follows:


Full Taper Springs: Part numbers may be found in one of these locations: (see illustrations below)

A. On the end of the last leaf

B. At the end of the wrapper

C. On the side, bottom or top of the clip


Multi Leaf Springs: Part numbers may be found in one of these locations:

C. On the side, bottom or top of the clip (most common)

D. On the end of the shortest leaf

E. On bottom of the last leaf beside the center bolt (sometimes this is hidden until the spring is removed)


Three Leaf Trailer Springs:

F. On the outside of the hook


In many cases, the number stampings may contain only a

part of the O.E.M part number.


Usually, Ford only stamps the prefix and the suffix and the base

must be added to complete the part number.


Example: Adding the 5310 base number to the F3HT prefix and

JA suffix completes the Ford Part number of F3HT5310JA which

interchanges to the SRI part number 43-434.

(Note: Other Ford OE part numbers could interchange with SRI 43-434).

Identification by vehicle make, model and year:


Where can the make, model and year be found?

1. Ask the customer

2. The truck-build sheet (line setting sheet)

3. On the vehicle's cab plaque (See Example)

4. Model may be displayed on the vehicle

Identification by spring dimensions:


This is by far the most difficult way to identify a spring and

should only be used if the first two methods detailed above

are unsuccessful.

What are the important measurements?

1. Main Leaf Length:

a. Eye to Eye - Measured from the center bolt to the center of the eye in both directions along the arch.

b. Eye to Slipper - Measured from the center bolt to the center of the eye and to the end where there is no

eye along the arch.

c. Slipper to Slipper - Measured from the center bolt to the end in both directions along the arch.

d. Camel Back (used on Mack only) - Measured from the center bolt to the end of the main leaf in both

directions along the arch.

e. Single Point (5" wide springs used on heavy duty trailers) - Measured from the center bolt to the end of

the main leaf in both directions along the arch. End hole size and distance from the center bolt must be

checked.

2. Spring Width:

a. Measured at the center bolt from side to side across the leaf.


3. Pack Thickness:

a. Measured at the center bolt down the side of the spring

including all leaves, tow eyes, shock eyes and pads.

Do not include any cast wedges or brackets.


4. Spring Arch: (always measure to the top of the main leaf, do not include any pads or spacers.)


a. Eye to Eye - Use a straight edge to mark the center of the eyes and measure the arch at the center bolt.

b. Eye to Slipper - Use a straight edge to mark the center of the eye and the top of the slipper and measure the

arch at the center bolt.

c. Slipper to Slipper - Use a straight edge on the top of the slipper ends and measure the arch directly over the

center bolt.

d. Camel Back and Single Point - Use a straight edge to mark the top of the main leaf in both directions and

measure the arch at the center bolt.

5. Eye Leaf Length: (radius leaf springs only)

a. Measured from the center of the eye to the center bolt.

Spring Eye Information:

1. No Eyes:

Typically no eyes are used on helper, trailer and rear single axle springs.

2. Eye Types:

Standard (Std) or Straight Eye

with or without bushing

Berlin (Ber) Eye with or without bushing

Reverse (Rev) Eye with or without

bushings (common on Dodge)

3. Bushings:

a. HB or Harris bushings (2 piece rubber bushing used in automotive and light duty applications). HB bushings are

not considered part of the spring and must be ordered separately. Catalog lists spring eye type and inside

diameter. (Example: Std/ 7⁄8")

b. RB or Rubber Encased bushings (metal encased rubber bushing used on most automotive, light, medium and

some heavy duty applications). Catalog lists spring eye type and bushing part number. (Example: Ber/RB-159)

c. TB or Threaded bushings (metal bushing with a threaded interior used on many old automotive, light, medium-duty

applications but more widely used on heavy duty applications). Catalog lists spring eye type and bushing part

number. (Example: Std/TB-68)

d. Bronze or Bimetal bushings (greasable bushing using spring pins with grease fittings). Catalog lists spring eye

type and bushing part number. (Example: Std/RNK)

Explanation of bronze and bimetal bushing part numbers

First (1st): Outside Diameter (OD)Second Second (2nd): Inside Diameter (ID)

Third (3rd): Length

Characters stand for certain sizes as listed

Even with complete measurements it can still be difficult to track down the correct spring unless the

make and model of the vehicle are known. Always try to obtain the make and model before beginning

the search.


Spring Ratings and Capacities:

Spring Ratings:

Springs are rated in several different ways throughout this catalog. A basic understanding of each and how they relate to the ratings of other components in a suspension are shown below.


Axle Capacity: Axles are rated several ways. The rating which is most important when discussing

springs is GAWR (Gross Axle Weight Rating). This is the maximum allowable load

which the manufacturer approves to be carried by that axle. Axle capacity is

measured at the ground and means the weight which a scale would read when

placed under the tires.


Sprung Weight: This is the weight of the vehicle that is supported by the springs themselves. This

includes the weight of the truck “above” the axles plus the weight of the driver, fuel

and any cargo.


Unsprung Weight: This is the weight not supported by the springs. It includes the axle(s), brakes,

wheels, tires and a portion of the steering components in the case of front axles.


Spring Capacities:

Published Spring Capacities (or ratings) may be given for either the sprung weight (at pad) or at the ground (sprung plus unsprung weight).


At Pad: The manufacturer’s maximum load rating of one spring as measured at the spring

mounting pad on the axle. This is the capacity that the spring itself is designed to

support. The balance of the weight is supported directly by the wheels and tires and

is not seen by the springs.


At Ground: This rating includes the At Pad capacity plus a portion of the unsprung weight. In

single axle applications, it equals the At Pad capacity plus one-half (1/2) of the

weight of the entire axle assembly.


Example:

Part Number 62-830

Spring Capacity At Pad 5,400 lbs.

+ 1/2 Axle Assembly Weight+600 lbs.

= Spring Capacity At Ground = 6,000 lbs. (12,000 lb. Axle)

Common Spring and Suspension Capacities:

Front Axle Rear Single Axle Rear Tandem 4 Spring

Spring Capacity

At Pad

Suspension Capacity

At Ground

Spring Capacity

At Pad

Suspension Capacity

At Ground

Spring Capacity

At Pad

Suspension Capacity

At Ground

3,150

3,550

3,800

4,050

4,500

4,850

5,400

6,000

6,300

6,500

7,200

8,200

9,200

10,100

10,600

7,000

8,000

8,500

9,000

10,000

10,800

12,000

13,200

14,000

14,600

16,000

18,000

20,000

22,000

23,000

6,750

7,500

8,000

8,500

8,900

9,400

10,400

12,000

13,000

14,000

15,000

17,000

18,000

19,000

20,000

21,000

23,000

26,000

28,000

31,000

7,500

8,000

8,500

9,000

10,000

10,500

34,000

36,000

38,000

40,000

44,000

46,000