Steering and Suspension 2019
Gary May Scope of Suspension And Handling
Drivers control and perception of ride quality.
Tire wear
Stability of unit
Longevity of components
ABS, ATC, RSC,ESC Inspection Guide lines By NFPA
All specification’s need to be with-in guide line by original manufacture.
Having repair and replacement specification’s from component manufactures is needed.
Owners manuals and Spartan Web Site has vast listing of chassis components repair and replacement manuals. Pre Alignment Test Drive
Test drive should included the following checks.
Pull to left or right on straight drive.
Pull to left or right when brakes are applied.
Wandering , bouncing, harsh ride, vibrations
Shimmy, excessive steering play Tire pressure
Correct tire pressure is determined by weight not by pressure on side wall of tire.
To get correct tire pressure use the website of tire manufacture, make sure you use the correct ply rating of tire.
Also have the in service weight of each axle for front axle add 250 lb. for any empty seat. 275/80R22.5 Load Range G
• Section width – Overall width of tire – 275 mm
• Aspect Ratio – Height of tire rim to tread 80 % – 80 (percentage of section width) 275
• The Math – 275 (Section width ) x 80 (section height – Section height measurement is 220 mm Reading Tire Inflation Charts
315/80R 22.5 LRL PSI 85 90 95 100 105 110 115 120 125 130
LBS Single 6470 6770 7070 7370 7660 7950 8240 8530 8810 9090 Dual 11770 12320 12870 13400 13940 14480 15000 15520 16020 16540 Date Code of Tires
Week tire was manufacturer Twenty second week. Year tire was manufactured 2003 Tire Marking Correct Inflation set by weight
80 psi, 440 sq. cm. 110 psi, 400 sq. cm. Tire Pressure to Weight Tread Type Tire Feathering
Tread ribs worn so that one side is higher than other. Caused by improper tow setting or worn parts. To check for this press one hand firm down on tread and run hand in and out accost tire if is smooth one way and sharp the other correct tow. Sharp going in towed in sharp going out towed out Tire Feathering Caused by Improper Tow
Tire with sharp edge facing in the tire is towed in. tire with the sharp edge facing out the tire is towed out. The further the tow is out of specification and the mileage on tire will determine the amount of tow correction needed. Tire Feathering Caused by Improper Tow
Unit with excessive tow in Tire Feathering Caused by Improper Tow
Unit with excessive tow out Checking Shocks Test to Perform on Return from Test Drive
Check all drums and rotors with heat gun and record.
Check all shocks with heat gun and record.
Uneven heat reading on brakes across axle is indication of brake problems.
Shocks that build heat are working. Pre Alignment Checks
Condition of tires.
Tire pressure to weight.
Wear to inside or outside of tires on steering axle.
Feathering of tires front and rear.
All suspension components for wear within manufactures specifications. Pre Alignment Checks
An incorrect toe-in will cause rapid tire wear to both tires equally. This type of tire wear is called a saw-tooth wear pattern.
If the sharp edges of the tread sections are pointing to the center of the truck, then there is too much toe-in. If they are pointed to the outside of the truck then there is too much toe-out. Toe is always adjustable on the front wheels Toe
Toe Definition: The difference between the leading edges of the front of the tires and the trailing edges of the rear of the tires on the same axle. Tires too close together at the front (+) or too far apart at the front (-) may lead to tire wear.
Purpose: Proper toe setting aids in directional stability and proper tire wear. If the toe is too negative, the vehicle may have a wander or pull condition.
Adjustment: Total toe is adjusted with one or two turn- buckle style tie rods. Toe Camber
Camber: Definition: The inward (-) or outward (+) tilt of the top of the tire.
Purpose: Camber helps to properly load the wheel bearings, and to maintain a straight ahead path. If the tire leans too far inward (-) or outward (+), not only may it accelerate wheel bearing wear, but can also wear the tire on the side to which it is leaning.
Adjustment: Most I-Beams are corrected by replacing the axle. Camber Caster
Caster Definition: The forward (-) or backward (+) tilt of the kingpin or steering axis.
Purpose: Proper caster helps the steering to return to center and assists the vehicle in maintaining a straight ahead path while providing stability.
Adjustment: Most I-Beams are tilted with a wedge, usually using the same wedge angle on each side, thus increasing (+) or decreasing (-) the total caster for the axle. Sometimes different wedge angles are used side to side*. Caster Thrust
Thrust Angle (One or multiple rear axles) Generally the rear axles need to be perpendicular to the centerline of the frame, and parallel to each other.
Definition: Simply put, thrust angle is the average direction an axle points away from the centerline of the frame, (+ is to the right and – is to the left). Thrust
Purpose: Thrust angle will always determine the vehicle direction of travel. Therefore in line with the vehicle centerline is generally preferred, but never pointed to the right side.
Adjustment: Normally thrust is adjusted with either a shim or a torque rod with a threaded sleeve. Occasionally an eccentric sleeve is installed at an end bushing. Thrust Angle Offset Angle
Axle offset angle
Purpose: When an axle becomes offset to the frame, it can accelerate suspension and drive line wear, affect the axle torque and may lead to a handling condition.
Adjustment: determined by suspension type Wheel bearing
Any wheel end that is equipped with disc brakes must have the brake backed off before checking for bearing end play. Steering System Checks
Any wheel end that is equipped with disc brakes must have the brake backed off before checking for bearing movement
Bearing adjustment should be .001” to .005” with dial Indicator. Radial Run Out
Maximum run out 80 thousands Lateral Run Out
Maximum run out 80 thousands Suspension Checks
According to the Commercial Safety Alliance (CVSA), the vehicle “out of service” criteria is: Any motion other than rotational between any linkage member and its attachment point of more than 1/8” (3mm) measured with hand pressure only. (393.209(d), (published in the North America Standard Out-of Service Criteria Handbook, April 1, 2006 Pre Alignment Checks
Ride height must be even side to side with air ride or spring suspension.
Truck must have wheel blocked and park brake release before checking ride height.
Air ride IFS front must have ride height check before alignment.
Rear air ride height must be set before alignment Front Spring Suspension Checks Spring pin wear
Loose U-bolts
Movement of spring bushing in spring or hanger.
Movement of spring leafs for and aft (bent or broken center bolt) Front Spring Suspension Checks
U bolt torque
Axle for correct set back
King pin movement
Tie rod and drag link ends for wear
Steering assist cylinder for wear
Leaning chassis Loose U-Bolts 7.3 Suspension Checks Spring Front Suspension Spring 7.3 Suspension Checks Spring
Check U-bolt torque Every year torque In correct pattern 7/8 U-bolts torque is 425lbft What is this and location Steering System Checks
King pin vertical end play 0.001 to 0.030
King pin bushing movement 0.001 to 0.010 Steering System Checks
Drag link ends
Tie rod ends
Applying 100 lb. force there should be 0 movement.
Check grease boots for damage and cracking. Suspension Checks Spring
Check for spring leaf movement.
Check for cracked or broken leafs.
Check for loose or missing hardware. Suspension Checks Spring
Check rear spring shackle.
Check pinch bolt for torque.
Check that spring pins are taking grease. Power Steering Checks
Condition of power steering fluid
Correct steering stop settings
Poppet relief settings
Condition of hoses
Steering shaft u-joints for lube and excessive play. Power Steering Checks
Using power steering analyzer check Relief pressure of power steering pump Flow Steering full left and right check pressure at steering stops Pressure at stops should be 200 psi to 400 psi lower than relief pressure Power Steering Checks
Pitman arm pinch bolt torque
Gear box mounting
Slip shaft lube and movement Spring Suspensions
Pre alignment check and periodic maintenance.
Every 2,000 miles or 1 year check all fasteners torque. U- bolt are high priority.
7/8 U-bolts torque is 425 lb. ft. using star pattern.
No broken cracked or missing leafs. Spring Suspensions Checks Rear
Reyco Granning 79 KB leaf springs suspension on rear of truck ordered with leaf spring on rear
Front spring suspensions can be 3,4,9,10 leaf front.
For manuals and torque speciation's www.tuthill.com 79KB Rear Suspension Torque Arm Bushings Effect of Loose U-bolts Loose U-Bolts Spring Suspensions
Shocks mounts and bushings.
Shocks for damage, broken eyes, oil leaking.
After driving truck for 3 to 5 miles on rough roads check for heat in shock if heat is present shock is working.
Using bar to check spring pins for wear. Spring Suspensions
Look for any movement of spring leafs, axle seats or spring mounting.
If movement of these parts are found then spring center bolt needs to be checked for being bent or broken as this will give false alignment settings. IFS Front Suspensions IFS Pre Alignment
Ride height must be check and set if needed before alignment.
Check a-arm bushings for wear.
Check king pin or ball joints for movement both vertical and lateral.
Check for split or missing ball joint boots A Arms Bushings Checks Bell Crank Checks A Arms Checks and Alignment Kingpins & Thrust Bearings
The suspension should be under load while lubricating the king pins to properly cycle grease through the Thrust Bearing.
Apply lubricant to the Zerk fitting on top and bottom of the kingpin bushings until new lubricant discharges from kingpin housing and the carrier. Air Ride Suspension
If primary air drains down to 65 psi and air ride suspension drops to axle stops leak is in air ride system.
Check all lines, leveling valves , air bags and exhaust line from leveling valve for leaks.
Check that air springs are not making contact with any component of truck that would cause damage to air spring. Air Ride Suspensions
Check ride height
Park brake must be released to check ride height.
Check air bags for damage or leaking check leveling valves for leakage bent or worn linkage.
Check all mounting bolts and hardware. Air Ride Suspensions
5B.6 Tighten adjuster clamp. 5B.7 Ensure the rod length from the center of the valve pivot point to the center line of the horizontal rod end is six- (6) inches.
Length of Check rod must mounting be same and length rubber on each side connectors
FIG. 4-1 ESC
Any adjustment of steering wheel to center the wheel will cause the steering angle sensor to be out of calibration and will need to be reset.
Changes to trust, scrub, ride height on spring suspensions and change of tire size the steering angle sensor will need to be recalibrated. ESC
ESC End-of-Line Procedure: This procedure must be performed as part of the final assembly of the vehicle at the OEM site and also should be performed in the field by a trained technician at all service locations, if all or any component such as the SAS, the ESC Module or the ECU have been replaced or a major steering system repair or replacement has taken place ESC
The process consists of 2 operations. The first one is the SAS calibration, followed by the ESC Initialization. The status of the ESC EOL procedure can be verified using one of the following allowed faults.
SAS not calibrated89 13
ESC initialization required 88 13
ESC initialization not completed88 01 ESC
NOTES: To prevent incorrect activations, “SAS calibration” and “ESC initialization” have to be separated. It is necessary to perform the SAS calibration prior to the ESC initialization.
For any questions or assistance, please refer all service, shop and field personnel to the Meritor WABCO Maintenance Manual or the ON-TRAC customer service center at 1 800 535-5560 or to www.meritorwabco.com for further details. ESC
ESC Initialization divided into 2 sections
Straight driving (800ft)
Offset verification of SAS
Offset detection for lateral accelerometer Left/right turn (app. < half circle)
Learn basic Dynamic Steering Ratio (DSR) for left and right turns Checking Poppets
If the steering angle on a unit is reduced, changing steering stops to reduce wheel cut, replacement of worn tie rod ends, changes in steering linkage on IFS suspensions. The steering poppets will need to be re-adjusted properly. Failure to reset poppets will cause damage to steering components and cause high steering fluid heat. Refer to TRW’S TSA Steering Gear Service Manual for readjusting the poppets. Pre Alignment Checks
Check all tires for correct inflation based on axle weight
Check front tires are the same size
Torque all wheel nuts to correct torque Pre Alignment Checks
Check all fasteners are tightened to the specified torque both front and rear
Check suspension ride height and adjust to specified ride height front and rear
Check for worn ball joints, tie rod ends, bushings, knuckle, carrier bearings, and damaged suspension components Pre Alignment Checks Replace worn components as needed
Check the wheel bearing adjustment (correct wheel end play is .001 to .005)
Inspect shock absorbers for wear and damage also if they build heat when truck was on road test driven Lubing Chassis
The suspension should be under vehicle load while lubricating the Kingpins to properly cycle grease through the Thrust Bearings. Lubing Chassis
Apply lubricant to the zerk fittings on top and bottom of the kingpin bushings until new lubricant discharges from between the steering knuckle kingpin housing and the carrier. Tie Rod Clamp Orientation Tie Rod End Check Tie Rod End Check
Cotter key missing
Stud or nut not torqued to specification
Grease Zerk missing or damaged Tie Rod End Check
Grease boot torn, split or missing
Excessive play in ball joint
Clamp not torqued or in incorrect location
Tire rod end not threaded in past slot