Identifying Air Bags Replacement Air Suspension Springs for Trucks
Air springs also called air bags may appear simple but air suspension components are actually highly sophisticated and complex. Air springs are produced in 1T reversible sleeve and convoluted styles and in many different configurations beyond that. The most common air suspension spring is the 1T reversible sleeve style. This guide will help determine the replacement product needed to replace failed air suspension springs. In some cases the Firestone Airide catalog is needed to augment this information. Our experienced customer service staf will gladly assist to find the replacement air suspension spring you need.
Read AON and bellows number.
The first step to identifying an air suspension spring for replacement is to read the assembly order number on the label adhered to the bead plate (i.e., W01-358-9082). If the number is illegible, read the bellows number which is normally molded directly underneath the Firestone logo on the air spring. A style number such as 1T15M-6 or 22 would tell exactly which bellows is needed and one could skip steps 2 and 3.
If the bellows number is illegible then determine whether it is a convoluted style or a 1T style by comparing it to the pictures in this guide. Proceed to step 2 if 1T style or step 3 if convoluted.
1T Style Air Springs
Measure the bead plate diameter and molded (unintiated) diameter of the rubber bellows on the air spring and compare this with the 1T styles in the bellows index in the catalog until a match is found (please note
that the molded diameter can grow slightly with years of service). Then measure from the bottom of the piston to the top of the bead plate while the part is uninflated and extended. Next, find this same or similar measurement in the specific bellows section that was previously determined. When this has been done, skip to step 4.
Convoluted style Air Springs
First determine whether the convoluted air spring is a single, double, or triple convoluted style by comparing it to the pictures in this guide. Then measure the bead plate diameter and the diameter of the bellows across its widest area (uninflated) and compare these dimensions with those given in the bellows index in the Airide catalog. Once a match has been made, proceed to step 4.
Many Airide air springs include a rubber bumper inside the spring. To determine if one is present, compress the air spring to its minimum height and measure from the bottom plate or piston to the top of the bead plate. Compare this compressed height with the pictures in the appropriate bellows section that was determined in step 2 (1T style) or step 3 (convoluted style). Proceed to step 5 if you have a 1 T style spring or step 6 if you have a convoluted spring.
1T Style Air Spring (bead plate and piston)
The same bellows is used with many different combinations of air springs, bead plates and pistons, so be sure to check closely to get the right air spring. Compare the bead plate and piston with the pictures from the "Cross Section View", "Bead Plate Top View" and "Piston Bottom View" columns from the appropriate bellows section that was previously determined. Also, verify that the alignment (bead plate mounting in reference to piston mounting holes, see catalog) is correct. In addition, the piston can be further verified by reading the identification numbers inside the piston on the air spring and comparing these with those shown in the "Piston Bottom View" or piston index in the catalog. Once a match has been determined, the corresponding assembly order number (i.e. W01 -358-9082) can be used to order the part.
Convoluted Style Air Spring (bead plates)
The same bellows is used with many different combinations of bead plates to make an air spring. Compare these bead plates with those diagrammed in this guide for the specific style convoluted part that was previously determined and find the unit with the identical hardware, measurements and alignment (top bead plate mounting in reference to lower bead plate mounting, see catalog). Once a match has been determined, the corresponding air spring assembly order number (i.e., W01-358-7135) can be used to order the part. The last 4 digits determine the Ryder Fleet Products number (W01-358-7135 equals U71 7135).
This documentation was provided by Firestone / Airide Springs.