MTE Tru-Ride Air Suspension Owner’s Manual GM 4500/5500

MTE Tru-Ride Air SuspensionOwner’s ManualGM 4500/5500 Operation Maintenance Troubleshooting Service PartsMONROE TRUCK EQUIPMENT1051 W. 7th Street Monroe, WI 53566800-356-8134 www.monroetruck.com05090311

NHTSA NotificationIf you believe that your vehicle has a defect which could cause a crash or could cause injury or death, you should immediately inform theNational Highway Traffic Safety Administration (NHSTA) in addition to notifying Monroe Truck Equipment.If NHTSA receives similar complaints, it may open an investigation, and if it finds a safety defect exists in a group of vehicles, it may order arecall and remedy campaign. However, NHTSA cannot become involved in individual problems between you, your dealer, or MonroeTruck Equipment.To contact NHTSA, you may either call the Auto Safety Hotline toll-free 1-800-424-9393 (or 366-0123) in Washington, DC area) or writeto: NHTSA, U.S. Department of Transportation, Washington, DC 20590. You can also obtain other information about motor vehiclesafety from the Hotline.NoticeSpecifications, parts descriptions, illustrations, and instructions in this manual were accurate at the time of publication. Monroe Truck Equipment, Inc. reserves the right to discontinue products and to change specifications anddesigns at any time without notice and without incurring obligation.Monroe Truck Equipment, Inc. is not responsible or liable for injury, damage, or loss caused by improper installation by the end user, misuse of the equipment, lack of maintenance, accidents, or failure to follow instructions. Incases where equipment application was determined by the end user, Monroe Truck Equipment, Inc. is not responsible or liable for injury, damage, or loss caused by misapplication of this equipmentMTE Air Suspension Owner’s ManualRevision Level July 28, 2008Copyright 2007Monroe Truck Equipment, Inc.1051 W. 7th StreetMonroe, WI 53566No part of this manual may be used, reproduced, or reprinted without the express written permission of Monroe Truck Equipment, Inc.

Table of ContentsSafety Warnings and Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Product Description & Specifications . . . . . . . . . . . . . . . . . . . . . . . . . 3Normal Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Emergency Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Routine Maintenance & Repairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-7Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-9Electrical Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Air Schematic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Service Parts4X2, 11K & 13.5K Axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13-204X4, 13.5K Axle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21-27Optional Equipment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-35Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36-371

Warnings & Safety StatementsDanger of electrical shock. High currentpotential at compressor power connection.WARNINGDisconnect the vehicle battery or removethe primary power fuse before removingthe compressor enclosure cover.Danger of injury from release of compressed air.The compressed air system normally operates at 120 psig. Sudden release of airpressure can cause eye injuries and loss ofWARNINGsight.Wear eye protection when working onthe air system components. Disconnectpower from the compressor and releaseall air pressure before working on the airsystem.Possible wiring damage or vehicle firefrom improper fusing.Do not bypass the supplied fuses in theelectrical circuits. Do not install fuseswith a higher current rating than thoseCAUTIONsupplied.If a fuse burns out, investigate and repairthe cause.The air suspension system is not considered to be user-serviceable.It is recommended that service and repairs be performed by a Monroe TruckEquipment facility or other truck equip-NOTEment repair shop.2

Product Description & SpecificationsProduct DescriptionThe MTE air suspension system replaces the OEM leaf spring suspension with swing arms and air springs (inflatable air bags). An airspring system provides a smoother ride and is self-leveling during all driving and normal loading conditions. Adjustable-dampening shockabsorbers are standard with all suspension kits.A rear sway bar is standard.The air suspension system requires an MTE air compressor unit and air reservoir.Operating Parameters and Specificationsx Required operating voltage (air compressor): 11 to 15 VDCx Operating air pressure (compressor shut-off) setpoint: 120 psig, 5 psigx Operating temperature range: -40 to 130o FShock Absorber SettingsSoftest SettingRStandard MTE SettingFHigh Center of Gravity Vehicles (Ambulances & Buses)XFTo adjust settings, follow directions on the shocks.Ride Height(Measurement “H” shown at right)4 x 2 wheel drive11.125”4 x 4 wheel drive12.0”So-Low 4 x 2 wheel drive8.625”HThe air suspension system is a loadleveling system designed to maintain aspecified ride height.The specified ride height sets the inflatable air bags at their mid-point of travelCAUTIONwhen the suspension is at rest.Operation of the vehicle with the rideheight set too high or too low may permanently damage the air bags.3

Normal OperationNormal Operation of the Air Systemy For normal operation, keep the Dump (Kneel) switch off.y Start the vehicle engine.If the air pressure in the system is low, the compressor will start immediately. When thepressure reaches the normal operating pressure, the compressor will stop automatically.y Normal maximum operating pressure is 120 psig.The compressor will start whenever the pressure drops to about100 psig.y Whenever the vehicle is running, you will hear the compressor start and stop occasionally.The frequency of com-pressor cycling depends on the amount of movement at the rear suspension. As the suspension moves, it consumesand releases air pressure to keep the chassis level. The more the suspension moves up and down, the more frequently the compressor will have to run.y To lower the rear of the vehicle when connecting a trailer, activate the Dump (Kneel) switch.The suspension willimmediately deflate. When the trailer is connected, shut off the Dump switch and verify that the suspension returnsto the normal ride height. Never drive the vehicle with the suspension in the Kneel position.y It is normal for the compressor to start when the Dump function is shut off and the suspension begins to inflate.Dump/Kneel Switch4

Emergency OperationSystem Operation During Compressor FailureIf the compressor or other component in the enclosure fails and the compressor will not run, air pressure can still bemaintained in the suspension system until repairs can be made. Use a compressed air source and a standard tire valvechuck to add air at the Schrader valve in the end of the air tank.y Do not exceed 120 psig when adding air to the tank manually.y If the vehicle must be operated for an extended period in the failure mode, air will have to be added occasionally tocompensate for losses due to movement of the suspension.y If there is an air leak in the system, manual filling of the tank may not be effective except for moving the vehicle ashort distance.y Do not use the Dump (Kneel) function if the system is operating in the failure mode.Manual air fill valveNever drive the vehicle with the air bagsdeflated. Permanent damage to the airbags may occur.If the compressor system fails, add airmanually to the air tank to allow the vehi-CAUTIONcle to be moved to a repair location.Repair the cause of the compressor system failure as soon as possible.5

Routine MaintenanceThe vehicle owner is responsible for inspection afterfirst 1,000 miles of operation, periodic inspections,maintenance, and proper use of the system.Suspension components must be inspected and allfasteners and U-bolts retightened after the first 1,000CAUTIONmiles of operation.Failure to retighten all suspension fasteners at 1,000miles may result in damage to suspension components or the axle.Refer to the Air Compressor Owner’s manual formaintenance information on the air system.NOTEFrequencyTaskBlow down moisture in air tank 1, 2WeeklyMonthlyAnnuallyOtherXActivate Dump (Kneel) functionXObserve/check ride heightXInspect wiring harnesses & air tubingXInspect shock absorbersXInspect suspension components and bushingsXInspect condition of air bagsXTighten suspension component fastenersXReplace at 50,000miles.Initial inspection afterfirst 1,000 miles.Initial check after first1,000 miles.Tighten every 25,000Notes1.Pull cable attached to drain valve at bottom of tank.2.If the air tank is equipped with the optional automatic drain valve, the valve should open briefly each time the compressor runs.6

Routine MaintenanceFASTENER TORQUE VALUESSpring Hanger to Frame:80 ft-lbsAir Spring Bracket to Frame:80 ft-lbsLateral Control Rod Bracket to Frame:80 ft-lbsLateral Control Rod Bracket to Axle (U-Bolts)150 ft-lbsLateral Control Rod Flange Nuts140 ft-lbsAir Spring mount to Spring Arm30 ft-lbsSpring Arm Axle Mount (U-Bolts)275 ft-lbsSpring Arm Front Mount Pivot240 ft-lbsShock Absorber Nuts60 ft-lbsRepairsy Major repairs and suspension component replacement should be performed by a qualifiedservice technician.7

Troubleshooting—SuspensionRefer to the Air Compressor Owner’s manual forinformation on troubleshooting air system problems.NOTEProblemPossible CausesSolutionsAir bags do not inflate—bags deflated1.Dump (kneel) switch on.1.Turn Dump function off.2.Compressor unit failure.2.3.Large air leak in system.Refer to troubleshooting instructions for air compressor.4.Leveling valve link rod(s) disconnected.3.Check for and repair leaks.4.Reconnect link rod(s), adjust rideheight if required.5.Inspect all air hose routings, re-5.One air bag deflatedPinched or kinked air hosebetween air tank and levelingvalve(s)1.Air bag ruptured, leaking.2.Leveling valve for bag disconnected or defective.3.1. Check for air leaks at bag, replaceif ruptured.2. Check leveling valve link rod. Reconnect and adjust. Replace valveif defective.Air hose to bag kinked orplugged.3. Check air hose, repair or replace.Ride height low, high, or unevenfrom side to side1.Leveling valve(s) not adjustedproperly.1. Adjust link rod(s) as required toachieve proper height.2.Leveling valve arm or link rod2. Repair or replace valve or link rod,then adjust for proper ride height.bent.3.Defective leveling valve3. Disconnect link rod and manuallyoperate the arm. If air bag doesnot move through full range oftravel, replace valve.Suspension does not respond whenweight is added or removed fromchassis.1.Leveling valve link rod(s) disconnected.1.Reconnect link rod(s), adjust rideheight if required.2.Leveling valve defective.2.Check and replace leveling valve.Excessive vertical movement ofbody on suspension or wheel hopunder hard braking1.Shock absorbers not set tocorrect firmness.1. Set shocks to higher firmness setting.2.Shock absorbers worn out.2. Replace shocks.8

Troubleshooting—SuspensionProblemPossible CausesSolutionsNoise or excessive lateral movement in suspension.1.Fasteners loose.2.Bushing worn.1. Tighten all fasteners for suspensioncomponents.2. Check all bushings and replace asnecessary.Rough rideSoft, mushy ride, poor handling.1.Tires over-inflated.1. Check and adjust tire pressures.2.Ride height set too low.2. Adjust ride height.3.Ride height set too high.3. Adjust ride height.4.Shock absorber settings toohigh.4. Check and adjust shock absorbersettings.1.Ride height set too low.1.Adjust ride height.2.Shock absorbers worn out.2.Replace shock absorbers.3.Worn out bushing in suspen-3.Inspect and replace bushings.sion components.9

Electrical Schematic10