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.