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Sion · 11-15-2003, 08:42 AM

There is another VERY good reason to ALWAYS have the brake (not break) rotors resurfaced or replaced when doing a disc brake job: to remove any glaze that has ocurred on the rotor, which lowers the coefficient of friction between the pads and rotos, thus lowering the stopping power of the system. note that this same concept also applies to drum brakes, in that the drums should ALWAYS be resurfaced or replaced when replacing the shoes.

irateplatypus, my advice to you is this (if you havent already done the job) consider getting a Haynes (or other brand) manual for your car (they usually run about $15 at a parts store). Carefully read the instructions BEFORE even attempting the job. Attempt the job ONLY if you are absolutely sure you fully understand what to do and are confident in your ability to do it correctly. As you said, competency is critical when it comes to brake system repairs.

now, all that being said, Ashton's instructions were pretty good, but he forgot two important things. First is to get a can or two of brake-clean, to clean the rotors off with before final assembly, regardless of wether they are new or resurfaced. New rotors have a coating of cosmolene (anti-rust agent) that should be removed before use. Resurfaced rotors (unless cleaned by the resurfacing shop) should be cleaned to remove any residual dust/grindings from the turning procedure. And of course, you dont want any dirt or grease on the pad surface or rotors. Last thing I always do before final assembly is to liberally spray down the pads and rotors with brake clean, because I always end up getting them dirty somehow. Let them air dry for a minute or so, then complete the assembly.

Second, and more important is the break-in drive. Once new pads are installed on resurfaced (or even new) rotors, the pads must be mated to the rotors on a break-in drive. This is done by taking the car out on the road once the repair is completed. Get it up to 20 mph, then firmly depress the brake pedal and come to a complete stop. Do not jam the brakes like in a panic stop. Just a firm, slightly quicker than normal stop is what you want. Resume driving for several minutes (to allow the brakes to cool slightly), then repeat. Repeat procedure at 5 mph increments up to 50 mph (a total of about 15 stops).

This break-in procedure accomplishes two things: mating the pad surfaces to the rotor, as well as curing the "glue" that holds the pad material together. This "glue" is an epoxy-resin type of stuff that uses heat for the final curing process. The break-in procedure is this final curing. Failure to properly break-in the pads will result in decreased stopping power as well as decreased pad life. I've even seen pads that have cracked and crumbled as a result of not being properly broken-in.

all that being said, it is worth noting that Bendix now makes a pad that does not have to be broken-in in this manner. There is a special coating on the surface of the pad that provides stopping friction during the curing/break-in period. By the time it wears off (a couple dozen stops or so) the pads are mated to the rotors and the curing is complete. I've used them once and was very satisfied with the results. You pay a bit more for them, but they are excellent quality pads with a lifetime warranty.

oh, one more thing: I implore ALL of you home mechanics to ALWAYS use quality brake pads, such as Bendix or Raybestos. Dont buy those cheapo piece of shit brands from discount auto parts stores. Remember, a car that wont start wont kill you, but one that wont stop most likely will. Spend the extra $10 and get good parts that you can rely on.

11-15-2003, 08:42 AM	#13 (permalink)
Sion Dumb all over...a little ugly on the side Location: In the room where the giant fire puffer works, and the torture never stops.	There is another VERY good reason to ALWAYS have the brake (not break) rotors resurfaced or replaced when doing a disc brake job: to remove any glaze that has ocurred on the rotor, which lowers the coefficient of friction between the pads and rotos, thus lowering the stopping power of the system. note that this same concept also applies to drum brakes, in that the drums should ALWAYS be resurfaced or replaced when replacing the shoes. irateplatypus, my advice to you is this (if you havent already done the job) consider getting a Haynes (or other brand) manual for your car (they usually run about $15 at a parts store). Carefully read the instructions BEFORE even attempting the job. Attempt the job ONLY if you are absolutely sure you fully understand what to do and are confident in your ability to do it correctly. As you said, competency is critical when it comes to brake system repairs. now, all that being said, Ashton's instructions were pretty good, but he forgot two important things. First is to get a can or two of brake-clean, to clean the rotors off with before final assembly, regardless of wether they are new or resurfaced. New rotors have a coating of cosmolene (anti-rust agent) that should be removed before use. Resurfaced rotors (unless cleaned by the resurfacing shop) should be cleaned to remove any residual dust/grindings from the turning procedure. And of course, you dont want any dirt or grease on the pad surface or rotors. Last thing I always do before final assembly is to liberally spray down the pads and rotors with brake clean, because I always end up getting them dirty somehow. Let them air dry for a minute or so, then complete the assembly. Second, and more important is the break-in drive. Once new pads are installed on resurfaced (or even new) rotors, the pads must be mated to the rotors on a break-in drive. This is done by taking the car out on the road once the repair is completed. Get it up to 20 mph, then firmly depress the brake pedal and come to a complete stop. Do not jam the brakes like in a panic stop. Just a firm, slightly quicker than normal stop is what you want. Resume driving for several minutes (to allow the brakes to cool slightly), then repeat. Repeat procedure at 5 mph increments up to 50 mph (a total of about 15 stops). This break-in procedure accomplishes two things: mating the pad surfaces to the rotor, as well as curing the "glue" that holds the pad material together. This "glue" is an epoxy-resin type of stuff that uses heat for the final curing process. The break-in procedure is this final curing. Failure to properly break-in the pads will result in decreased stopping power as well as decreased pad life. I've even seen pads that have cracked and crumbled as a result of not being properly broken-in. all that being said, it is worth noting that Bendix now makes a pad that does not have to be broken-in in this manner. There is a special coating on the surface of the pad that provides stopping friction during the curing/break-in period. By the time it wears off (a couple dozen stops or so) the pads are mated to the rotors and the curing is complete. I've used them once and was very satisfied with the results. You pay a bit more for them, but they are excellent quality pads with a lifetime warranty. oh, one more thing: I implore ALL of you home mechanics to ALWAYS use quality brake pads, such as Bendix or Raybestos. Dont buy those cheapo piece of shit brands from discount auto parts stores. Remember, a car that wont start wont kill you, but one that wont stop most likely will. Spend the extra $10 and get good parts that you can rely on. __________________ He's the best, of course, of all the worst. Some wrong been done, he done it first. -fz I jus' want ta thank you...falettinme...be mice elf...agin... Last edited by Sion; 11-15-2003 at 08:47 AM..