Shortcuts and poor workmanship
Most brake comebacks result from not paying attention to detail when performing the brake job. Taking a few extra minutes when performing the service will eliminate the vast majority of comebacks from ever happening. It sort of follows the old saying “pay me now or pay me later”. The difference is paying now involves only a few extra minutes per job and paying me later involves a few extra hours. Here are the steps to take during a brake job:
1. Where possible open the bleeder when retracting caliper piston. The brake hose can also be line locked as an extra precaution (use only approved line locks). These steps will prevent back flushing dirty fluid through the system. If it is not possible to open the bleeder screw, push the caliper piston in slowly to prevent building back pressure. Taking approximately 60 seconds to push the piston back in will reduce the back flush pressure generated to a safe level. When using this step it will be necessary to drain some fluid from the master cylinder reservoir. Either step will reduce the chances of potential damage to the ABS modulator, brake valving or master cylinder.
2. Check all hardware and replace as needed. Weak or worn hardware is a leading cause of uneven and premature pad wear. Restoring the hardware to proper working condition will help to ensure even pad wear and longer pad life.
3. Clean and lubricate all contact points. Metal to metal contact points should be lubed with Moly Lube. Only a small amount is needed to do the job correctly. Metal to rubber parts should be lubed with a high quality silicone lube. The silicone will not damage the rubber parts and helps to form a moisture barrier.
4. If resurfacing the rotor(s) use proper machining techniques and make sure the lathe is in good working condition. On hubless rotors make sure to clean the mating surfaces with an appropriate tool. Scratch cut all rotors to ensure accurate setup. Always use sharp bits and a vibration damper when machining. After machining apply a non-directional finish using 120 grit drywall sandpaper on a rubber sanding block for 60 seconds per side.
5. Clean the rotor before installing on vehicle to prevent machining dust from contaminating brake pads. The best method to accomplish this is to use a mild soap and water solution. Wash both friction surfaces and wipe dry with a clean lint free rag or paper towels. If using brake clean, use a little more than usual and wipe the surface with a clean lint free rag or paper towels while it is still wet. NEVER use petroleum based cleaners because they leave a residue.
6. Before installing hubless rotors, clean the hub mating surface using an appropriate tool(s). Failure to properly clean this surface can prevent achieving the proper installed runout.
7. When installing new or machined hubless rotors the installed runout should be checked. Using spacers on the studs tighten all lugs to the proper torque using the correct sequence. If runout is not less than manufacturer’s specification index the rotor on the hub to achieve the lowest amount of lateral runout. Before indexing mark the high spot on the rotor and hub. Indexing involves removing the rotor and rotating it one or two lugs and reinstalling. Repeat this until the installed runout is below specification. If runout is out of specifications and does not change as the rotor is rotated check to see if the high spot moves with the rotor or stays with the hub. Failure to install the rotor with installed runout less than manufacturer’s specification is the leading cause of reoccurring pulsation comebacks.
8. Properly torque the wheel lugs using either a hand torque wrench or torque stick sockets. When torquing wheels use a step torque process. To step torque the lugs tighten all lugs to half the normal torque using proper sequence and then fully torque lugs using same process. Make sure your impact has been calibrated before using torque sticks.
9. Test drive the vehicle to ensure proper operation and to break the new friction in. To break the friction in make 10 to 20 stops from 30 M.P.H. down to about 10 M.P.H.. Allow about 30 seconds in between each stop for cooling. This process will properly mate the new pads to the rotor surface.
10. Deliver the vehicle and instruct the customer for the first 200 miles they should try and avoid panic stops and not to tow or haul heavy loads.
Following these steps each time will reduce, if not eliminate comebacks.