- This topic has 4 replies, 5 voices, and was last updated 14 years, 1 month ago by TrialsRider.
Brake job
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March 16, 2010 at 1:17 am #3759rogestro1Participant
I think I need to do my back brake on my bike. It’s squeeking and there is a grove in the rotor. Is it going to be an expensive job to pay for?
March 16, 2010 at 3:32 am #24967eternal05ParticipantWhat do you mean? Given your symptoms, it could be any number of things ranging from a simple brake pad swap to a total rebuild (or replacement) of your caliper.
March 16, 2010 at 4:35 am #24969MunchParticipantdoubt its gonna be a rebuild of the caliper….unless it’s locking up or failing to engage. First thing you need to do is look between the pad and rotor to see if there’s debris in there causing the gouging. While your at it look at the pads themselves and gauge the thickness to MoM’s recommendations. Don’t have it… .take it to the mechanic. The other thing you will need to do is check how bad that groove is. It can adversely effect your braking efficiency. The caliper is an easy enough check. Try and push the piston back….if it collapses… your good (for the most part), then grab a hand full of brake and make sure it goes back out…but before you do make sure pad travel is relatively free of obstruction.
The hardest part will be your rotor if it is deemed bad…. and even then not so hard, depending on bike and placement of body parts.March 16, 2010 at 1:36 pm #24970IBA270ParticipantUnfortunately, the VAST majority never change the brake fluid on their bikes. Over a period of time, moisture accumulates in the system and causes all sorts of problems. Along with that, many people do no properly inspect the brake pads for wear, and, if the bike has some miles on it, the thickness of rotors.
Check: pads and rotor for wear, and consider bleeding your system. It’s a ten minute operation once you understand how to do it, and you’ll notice a difference right away.
Last thing to consider; if you haven’t serviced your bikes brakes at all, consider your riding style. 70% or more of your braking power comes from the front brake(s). If the rear is wearing much faster than the fronts, your riding style may be culprit. I have obviously have no idea, just trying to offer some suggestions and solutions to keep you and your bike on the road!
March 16, 2010 at 5:09 pm #24977TrialsRiderParticipantOn my competition bike I dismantle, clean and service my brakes (and for that matter, everything else) about 4 times a year. None of my disk brake systems have ever needed significant caliper repairs, the caliper is simply a hydraulic ram and should be serviceable as long as it doesn’t loose fluid and you don’t physically damage the ram piston skirt ( the ram or piston or puck is the round, moving part that pushes against the brake pad).
If the pads are wearing unevenly that’s a sign of poor alignment somehow. Disk groves are generally caused by stones wedged between the caliper and disk, a incorrectly mounted caliper or a completely worn brake pad. Quality brakes have two, four or six opposing pucks and pads normally wear evenly, if one ram sticks more than the other, the pads will wear unevenly. If the caliper bracket is misaligned the pads will wear wedge shape and the caliper assembly will grind away where it contacts the disk.
The pads can develop a glaze from extreme use, heat, dirt and water, but they can be hand sanded to remove the glaze and work great again, provided they have enough material left. Similarly the disk can be cleaned up with emery cloth, it should be rust free and have a dull finish, not a shiny mirror finish. If the friction pads are good; mushy brakes, or brakes that self apply when they are hot, is generally the result of air in the line. It is a basic principal of hydraulics that fluid does not compress or expand in a closed system, but air anywhere in the system will compress giving a mushy feel to the brakes and expand when it gets hot. Water and dirt in the brake system is also a problem, it will result in you needing to replace the brake fluid completely.
Only use the specified fluid, some brake fluid is specifically for teflon applications and can damage the natural rubber seals on some systems, others may not handle the high temperatures created by extreme pressure and heat transfer from the brake pads friction.
The caliper ram is made of fragile metal just like your engines piston. As with almost all disk brakes; the pads have no return springs, they are either applied, or lax. Never pump the brakes with the caliper dismantled and nothing placed between the pucks, or they will travel all the way out and dump the brake fluid, keep a piece of wood or something like a wooden ruler, positioned between the caliper pucks when you are working on them ( should be approximately the same thickness as the brake disk plus one pad in thickness), that way you have something for the rams to work against, and you can use the wood to pry the piston pucks back open without damage. ( wish I had a video of the caliper service procedure, maybe best if you have someone with experience show you the first time )
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