K28501552
Service Bulletin Details
Public Details for: K28501552
Mack chassis - models gu / chu steering wander
- 2020 - 2019 - 2018 - 2017 - 2016 - 2015 - 2014 - 2013 - 2012 - 2011 - 2010 - 2009 - 2008 - 2007 -
Models from 2020
2020 MACK PINNACLE (CHU) |
Models from 2019
2019 MACK GRANITE (GU) |
2019 MACK PINNACLE (CHU) |
Models from 2018
2018 MACK GRANITE (GU) |
2018 MACK PINNACLE (CHU) |
Models from 2017
2017 MACK GRANITE (GU) |
2017 MACK PINNACLE (CHU) |
Models from 2016
2016 MACK GRANITE (GU) |
2016 MACK PINNACLE (CHU) |
Models from 2015
2015 MACK GRANITE (GU) |
2015 MACK PINNACLE (CHU) |
Models from 2014
2014 MACK GRANITE (GU) |
2014 MACK PINNACLE (CHU) |
Models from 2013
2013 MACK GRANITE (GU) |
2013 MACK PINNACLE (CHU) |
Models from 2012
2012 MACK GRANITE (GU) |
2012 MACK PINNACLE (CHU) |
Models from 2011
2011 MACK GRANITE (GU) |
2011 MACK PINNACLE (CHU) |
Models from 2010
2010 MACK GRANITE (GU) |
2010 MACK PINNACLE (CHU) |
Models from 2009
2009 MACK GRANITE (GU) |
2009 MACK PINNACLE (CHU) |
Models from 2008
2008 MACK GRANITE (GU) |
2008 MACK PINNACLE (CHU) |
Models from 2007
2007 MACK GRANITE (GU) |
2007 MACK PINNACLE (CHU) |
Solution K28501552 Monday, February 4, 2019 6:37:38 PM CET Mack Models Mack Model Conventional , CHU - Pinnacle, Axle back , GU - Granite Engine family Engine family Mack , MP7 , MP8 , MP10 Emission Standard Emission Standard US10+OBD13 , US14 , US14 CNG , US15 , US16 , US17 , OBD2017 ** SOLUTION ** Title Draft Mack Chassis - Models GU / CHU Steering Wander, Will Not Center Cause There have been reports of certain Mack Trucks - Models GU / CHU experiencing steering wander often at times perceived as constant correcting back to center or not holding a true line. GU/CHU Wandering Solution Often times perceived as constant correcting back to center or not holding a true line. Vehicle Checks (CHECKS MUST BE PERFORMED 1ST) Tire design and pressure. Over pressurized tires may cause adverse handling. Tire damage, uneven or extreme tread wear or mismatched tires/sizes. High tread block tires (ex. Bridgestone 426EL) may ride on the center sip of the tire causing the truck to drive from the ‘rear’ causing a need to constantly correct with the steering wheel. If vehicle has a 5th wheel, is it lubed properly, does wandering only happen with a trailer? Basic alignment specs i.e. toe, thrust line, etc. Turning torque at the steering wheel nut, depending on surface area tested on, tires pressures, etc. avg. 60-75in lbs. or less. Diagnosis can be completed by breaking the system into smaller sections (upper vs. lower, etc.). Looseness or binding in the following components: Steering wheel or steering column U-joints or slip joints in upper steering system Steering gear (diagnose per manufacturer’s specifications i.e. flow /pressure) Pitman arm Draglink ends and adjustment areas Kingpins/bushings Tie rod ends Spindles Wheel bearings Lug nuts Springs/spring hanger brackets Front and rear axles and u-bolts Steering box mounting, miss mounting may result in distortion of gear Alternate Cab Wall Boot For vehicles produced prior to 1st week of January 2017. A change of the upper steering column happened in November of 2014 (4mm shorter). With this change we believe an interference may have been created with the column boot on the cab wall. This may create undue pressure on the column shaft as it comes out of the cab wall. Pressure from the boot may be applied to the steering column shaft restricting it from turning freely. To check, disconnect upper steering shaft at base of column shaft. Remove boot (there may be a noticeable movement upward of the shaft). Reassemble steering shaft to steering column and test drive. If problem is resolved replace boot with 84723313 (Introduced into production 2017w01). Test drive after boot replacement to ensure problem is resolved before returning truck to customer. Alternate Steering Gear/Shaft Configuration On non-assist gear trucks we have a steering gear from Sheppard with a 90° miter box on top. This can be used with an Anthem 1 piece steering shaft. Sheppard steering gear part # 8148-SD110PAE3. Steering shaft 84703023 x 1. Screw 25106380 x 2. Nut 25098472 x 2. Follow Impact service procedures for gear and shaft replacement. Clearance to any component must be a minimum of 1”. Pillow block bearing bracket may be left in place and trimmed off or not. Slightly stiffer steering may result. May improve as components wear in. Use 84734967 as the causal part in the claim. Solution visibility Dealer distribution Function(s)/component(s) affected Function affected steering , tires/wheels Function Group Function Group 641 steering wheel, column lock, steering column, shaft Customer effect Main customer effect Poor straight-line directional stability , diagnostics/methodology , efficiency/abnormal behavior Road behaviour driveability Conditions Vehicle operating mode Frequency of occurrence of problem Administration when driving , cornering always Author RU1991v Last modified by RU4469V Creation date 21-02-2017 22:02 Date of last update 01-02-2019 14:02 Status Draft copy Average score 0 Number of scores 1