Brake caliper question
in [Toyota]
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From: msrdude on 15 May 2010 03:01 How do you check brake caliper, and when should it be replaced?
From: Hachiroku ハチロク on 15 May 2010 13:08 On Sat, 15 May 2010 00:01:42 -0700, msrdude wrote: > How do you check brake caliper, and when should it be replaced? There isn't really a 'check', and as for replaced...? Calipers are pretty durable, either cast iron or cast aluminum. All it is is a passageway or series of passageways with a hole at the end of them. The hole holds the "puck", or piston. When you depress the brake pedal, hydraulic fluid flows and forces the piston out of the cylinder against the brake pads. Gummy brake fluid can cause the passageways to clog, but they're pretty beefy so this doen't happen too often. The most common failures are the piston sticks (usually because the dust boot failed) or the slides get sticky. The slides are the pins that the bolts that attach the caliper to the backplate slide through. This allows the caliper to slide a little to relieve the pressure on the pads. If these stick the caliper can get stuck in the outer position, and if the brakes are worn too far down the piston can come out of the cylinder and get stuck against the pads, or fall out altogether. If it stick in the inner position, the brake pads are constantly held against the rotor. There are rebuild kits for calipers. It's a bit of a pain, but if you have more time than money you can save quite a bit with a rebuild kit. It usually includes a seal, dust boot, piston and slides; some don't have the piston. They can be reworked quite easily with a Dremel and emory cloth, esp if the slides are sticking. So, when do you actually *replace* the calipers? When Midas tells you to!!!
From: ron on 15 May 2010 15:40 I'd suggest if there is no evidence of the pad dragging nor fluid leak to leave them along! With that said, Nissan in the 80's recommended a fluid change for ALL the fluids (not a flush) at 60k or 5 years. BTW, when you replace the pads the service tech should let you know about caliper condition
From: Ray O on 16 May 2010 21:19
"msrdude" <kimiga(a)gmail.com> wrote in message news:fa9b85ab-f9ad-40e6-8847-2045abac5a9d(a)o1g2000vbe.googlegroups.com... > How do you check brake caliper, and when should it be replaced? Hachiroku's explanation is pretty right on but to answer the questions: Brake calipers are checked visually and functionally to see if the piston(s) move freely and if the caliper has slides, that the slides and sleeves move freely and that there are no fluid leaks. Depending on caliper design, some calipers have one piston, while some have more. Our Sequoia has 4 piston calipers and no slides. Calipers should be replaced or rebuilt if the piston doesn't move freely, if the slide or sleeve can't be freed up, if there are fluid leaks, or if the caliper has been physically damaged. -- Ray O (correct punctuation to reply) |