![]() ![]() GM has had difficulty building hub/rotor to. GM has had major runout problems with Malibu ("Warranty problems though the roof"). That's why it is so important to inspect and clean mounting area between hub and rotor. Major cause of rotor runout is rust & corrosion between hub and rotor, and improper lug nut torque loading. Maximum runout will vary according to the vehicle, but on Chevy Malibu should only be 0.04 mm (0.0015 in.) max. To measure lateral runout, mount rotor on hub, install special conical washers (J45101-100) on lugs, then install and torque lug nuts to specs. If the rotor pulsates, it has thickness variation and is bad. You can't measure rotor thickness with a high degree of accuracy unless you measure about every couple inches all the way around the rotor. In the real world, the only things you can measure accurately are rotor thickness and flatness. GM says measuring rotor thickness variation is very hard to do accurately in the shop, so why waste time trying to measure it? GM spec for maximum allowable thickness variation in rotors is 0.025 mm (0.001 in.). If a customer has a brake pulsation, you know you have variation so rotors will have to be resurfaced or replaced. 002 runout, may not create a brake pulsation right away but it will appear within few thousand miles. Must measure assembled lateral runout to see if correction is needed. ![]() NOTE Very important to clean any rust/dirt/corrosion from hub anytime rotor is removed from hub. New manual section covers basics of measuring and correcting Lateral Runout (LRO) Correction. Is also paying increased labor rate to cover time needed to make measurements and corrections (a few extra tenths of an hour labor). GM added four new categories to service manual procedures to cover brake rotor replacement (went from 1 page to 16). ![]() Presented by Russ Dobson - GM Service Operations, Warren Tech Centerīrake pulsation has been a high warranty issue for GM. General Motors Brake Service Recommendations It's also interesting to note that the engineers from Ford, General Motors and Chrysler expressed opposite views on several important issues, including procedures for correcting brake pulsation problems caused by rotor lateral runout (GM approves the use of tapered alignment shims behind the rotors, but Ford and Chrysler do not.), the use of a lubricant or anti-corrosion treatment between the brake rotor and hub (Ford said yes, GM said never), and the use of brake pads that contain ceramic fibers (Ford and GM use them but Chrysler does not). In some cases, they expressed their own personal opinions rather than an "approved" service policy (no lawyers were present). Keep in mind that the responses given by the OEM engineers reflect their opinions towards new car dealer warranty service procedures and fixes, not necessary repairs that work for the aftermarket.Īlso keep in mind that the responses given by the individual engineers are not necessarily the "official" policy of the vehicle manufacturer they represent. The purpose of this event was to allow aftermarket tech trainers to quiz OEM brake engineers about their recommend brake service procedures, new brake designs and any problems they are experiencing in their shops. The event, was sponsored by Pro-Cut International, a manufacturer of on-car brake lathes. The information in this article came from a technical symposium attended by trainers from General Motors, Ford & Chrysler, also Firestone, Goodyear, Big O Tire, Car-X, Merlin, Midas, Monro, Sears, Tuffy, Pep Boys, ProCare and others. BIG 3 BRAKE SYMPOSIUM: Vehicle Manufacturer Advice on Brake Service ProceduresĪutomotive Repair Library, Auto Parts, Accessories, Tools & Equipment, Manuals & Books, Car BLOG, Links, IndexīRAKE TECHNICAL SYMPOSIUM Vehicle Manufacturer Advice on Brake Service Procedures
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