IK1400023 ­ IROS Suspension Lean

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Countries:

CANADA, UNITED STATES, PUERTO RICO Document ID: IK1400023

Availability:

ISIS, Bus ISIS, FleetISIS

Revision:

8

Major System:

REAR AXLE

Created:

9/4/2012

Current Language: English

Last Modified: 6/25/2014

Other Languages: NONE

Author:

Viewed:

Jon Pierce

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Title : IROS Suspension Lean
Applies To : All Buses and Trucks with IROS Suspension

Dealers: Please refer to the change log text box below for recent changes to this article:
6/25/2014 - Requested Spanish Translation
6/5/2014 - Published to field

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DESCRIPTION
This article is to be used when diagnosing chassis leans on Buses and Trucks with IROS suspension only. This does not apply to Tractors. By
following the steps below and giving the information requested we can expedite the troubleshooting process.
CAUTION :
Shimming is not an acceptable practice for chassis lean created by the addition of auxiliary equipment or loading practices resulting in vehicle lean.
These procedures are intended to assist the service technician in making industry acceptable corrections for nominal lean issues and are not intended
to compensate for over/uneven loading or un-repaired vehicle damage - regardless of cause.

• On an air ride suspension, replacing the air spring or the MSM (main support member, aka – rear spring) will not have any effect on lean.
• Warranty will NOT COVER replacing a spring for the following complaints:
◦ Weak spring
◦ Leaning
◦ Bottoming out
◦ Lost arch
You will need to fill out THIS FORM using the Troubleshooting information below to obtain accurate information.

TROUBLESHOOTING
1. Check the unit for any offset loading
◦ Note any items that may cause offset loading
2. Inspect the suspension for any third party (bodybuilder) installed components such as stabilizer bars
◦ International does not install stabilizer bars on most suspensions
◦ Execptions: BE Buses, Front suspension on CityStars, and the Multi-Link front air suspension (These will have stabilizer bars)
3. Check the tire pressure for all tires.
◦ Adjust pressures if needed.
◦ Record current tire pressures.
4. Verify ride height is properly set per instructions below.
◦ Park the vehicle unloaded on a level surface with a light application of the brakes.
◦ Do not apply the parking brake. Chock wheels to prevent vehicle movement.
◦ Make sure 120 psi is in the vehicle air system, and then shut off engine.
◦ Dump air from system, then re-pressurize and allow it to return to the ride height.
◦ Measurements are taken at the air spring assembly closest to the height control valve (usually forward left).
◦ Measure the vertical distance from the bottom of the straight edge that is resting against the u-bolts, to the bottommost position of the axle
stop.
◦ There should be no angle created between the two measurement points.

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IK1400023 ­ IROS Suspension Lean

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◦ If your outside the listed values on the table below, the height control valve will need to be adjusted. If adjustment is needed CLICK HERE
Table 2 - IROS Suspension Height Adjustment Specification Chart
Conf.

Model

IROS Suspension Feature Code

Axle Travel in Inches (measured from axle stop, see Figure
2)

14UNN, 14UNM, 14UNL, 14UNS, 14UNT, 14UNU

6x4

All

2.75 ± 0.125 or 2 3/4 ± 1/8

14TBJ

4x2

7000, 8000, 9000

2.75 ± 0.125 or 2 3/4 ± 1/8

14TBJ, 14TBG, 14TBH, 14TBK, 14TBR, 14TBS,
14TBT
NOTE: Above Codes are not with 14WAW
NOTE: For 14TBS, 14TBT Verify Model

4x2

3200, 4000. CE 200, CE 300, FE
300

3.0 ± 0.125 or 3 ± 1/8

4x2

RE 200, RE 300

14TBS, 14TBT

2.375 ± 0.125 or 2 3/8 ± 1/8

NOTE: For 14TBS, 14TBT Verify Model
14TBL, 14TBM, 14TBN
NOTE: Verify Build Date

4x2

4000

4.6 ± 0.125 or 4 5/8 ± 1/8
Models built before 02/23/2004

­

­

­

3.2 ± 0.125 or 3 3/16 ± 1/8
Models built starting 02/23/2004

14UNH

6x4

9000

1.55 ± 0.125 or 1 9/16 ± 1/8

14TBY

4x4

CXT, 7000

3.1 ± 0.125 or 3 3/32 ± 1/8

14WAW (Flat Floor)

4x2

3000

2.7 ± 0.125 or 2 11/16 ± 1/8

14TCH

4x2

TerraStar

3.0 ± 0.125 or 3 ± 1/8

14TCP, 14TCR

4x2

AE Bus

3.0 ± 0.125 or 3 ± 1/8

All dimensions are in inches.

5. Once the proper ride height is set, and air bags are inflated with 120 psi, measure each corner of the vehicle from the bottom of the frame to the
ground and record measurements.
6. Measure from the center of the bar pin to the ground and record.
◦ You must remove the Spring Eye Bushing mounting bolts.
◦ Using a frame jack at the rear of the vehicle, raise the frame evenly until the Bar Pin clears the Mounting Bracket on both sides.
◾ The rear tires should still be on the ground during this procedure. Only lift the rear of the frame until the Bar Pin clears the mounting
bracket.
◾ This will help determine if there is an issue with a rear seat or rear seat mounting.
◦ See image below.

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IK1400023 ­ IROS Suspension Lean

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7. Take a 1 1/2" to 2" inch block and drive on top of it so the block is located under the Front tire with the lowest reading.
◦ Remeasure from the bottom of the frame to ground and record.
◾ This will show us how the suspension reacts and if shimming will help to correct the issue. (If the lean is present in the front only)
8. Dump the air from the suspension and verify the frame stop is touching the axle U bolt on both sides of the truck.
◦ Remeasure from the bottom of the frame to the ground and record with the suspension dumped.
9. Record the axle seats degrees or part number on the physical part if possible. See images below.

PARTS INFORMATION
PART NUMBER
493720C3
540069C3
493721C3
N/A

DESCRIPTION
4 Inch Wide x 1/4 Inch Thick Spacer
4 Inch Wide x 3/8 Inch Thick Spacer
4 Inch Wide x 1/2 Inch Thick Spacer
3 Inch Wide x 1/2 Inch Thick Spacer**

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IK1400023 ­ IROS Suspension Lean

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**Obtain Locally
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