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Brake Caliper Rebuild?

Old 02-26-2006, 05:02 PM
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Brake Caliper Rebuild?

Where can I find a brake calpier rebuild kit? I was checking my calipers yesterday and found that at least one of the pistons was slower than the rest on each side. Also I want to know where to get cheap but good SS brake lines.
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Old 02-26-2006, 07:27 PM
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Re: Brake Caliper Rebuild?

I rebuilt the RC 51 calipers I bought before mounting them... got everything from Ron Ayers.... was easily half the price of the local Honda dealer (who I hate anyway). Even still it's a good 40-50 something dollars in gaskets from what I remember... (2) per piston and each are in the 3-4 dollar range... and don't forget the little gasket that bridges the caliper halves.

J.
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Old 02-26-2006, 10:37 PM
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Dude.. I would just try to buy somebody's calipers. I have like 4 sets here at my garage. Do you want a set?
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Old 02-27-2006, 12:31 AM
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Ok here is the situation I removed the calipers from the brake rotor assebly one at a time and squeezed the lever. On each side I had at least one piston that did not move till there was pressure on the others. Is that normal or should they all advance at an equal rate? None of them were siezed, they just seemed to be sticking until the others were fully extended. I guess what I am asking is "How do I know if a rebuild or new calipers are needed?"
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Old 02-27-2006, 06:06 AM
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Re: Brake Caliper Rebuild?

There are different sized pistons on each side (one large/one small).... I'd think that could contribute to the effect your describing, as more pressure on one than another could cause one to move before the other... just a thought....

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Old 02-27-2006, 06:24 AM
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Big piston will get biger pressure, if there're same friction on the piston, big piston will move first. right?

But I think in normal condition the pistons don't move, they just put more pressure on the discs.
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Old 02-27-2006, 07:45 AM
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Although it's just postponing the inevitable, you can try and clean them.

First, remove the calipers ONE AT A TIME and lightly apply the brake lever with the pads still in until they just touch. This will allow the pistons to travel out more than usual since the rotor is out of the way. You should see some clean pistons sticking out of the bores now.

Remove the pads if you didn't push them together too hard. Get a toothbrush and brake cleaning agent and get busy. Get as much crud/dust out and the pistons as clean as possible. Carefully push the pistons back in one side at a time, reinstall pads, and mount.

I do this anytime I change pads or front tire. Of course if you see evidence of leaking, time to order parts.
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Old 02-27-2006, 08:04 AM
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Originally Posted by superbling";p=&quot View Post
Get as much crud/dust out and the cylinders as clean as possible. Carefully push the cylinders back in one side at a time, reinstall pads, and mount.
I think he meant pistons...although it's not a bad idea to clean the cylinders as well because they do get gunked up, but if your going to have them apart you might as well do the whole thing. How does the fluid in the res. look? Is it clean, does it get dirty quickly? This will usually give some idea of what the insides of the calipers look like.
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Old 02-27-2006, 08:42 AM
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Yup, I meant pistons. Edited for clarity. Not enough coffee before posting! :-)
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Old 02-27-2006, 09:37 AM
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Still in the morning fog eh?
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Old 02-27-2006, 02:43 PM
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Re: Brake Caliper Rebuild?

I have just done full reco on mine. I used compressed air to pop the pistions out. If you are going to do this watch out, as those suckers came out with a rush!!
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Old 02-27-2006, 06:22 PM
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Re: Brake Caliper Rebuild?

Originally Posted by shayne";p=&quot View Post
I used compressed air to pop the pistions out.
If you use this method use a rag inbetween to keep from damaging anything and word to the wise keep your fingers clear. I made that mistake on some Ford calipers.....couldn't feel my fingers for a few hours after.
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Old 02-27-2006, 06:35 PM
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Calipers need rebuilding when the leak or stick. Rate of travel is not a diagnostic test.

These things are so simple, its virtually impossible not to be able to tell when they are bad. If you're not having a problem with leaks or sticking, I don't think you have any problem.
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Old 02-27-2006, 06:50 PM
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Yes but it's always better to rebuild before you have a major problem. If you're already having a problem then you can run into pitting. Keep the fluid clean and you have less chance of things going bad as well. If you look at his first post he was worried about sticking.
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Old 02-27-2006, 08:08 PM
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I just realized none of us fully answered your question. The way to know is, if the piston moves freely,(comes out with pressure goes in fairly easy when pushed), then it's probably not sticking. Pressure is not really unified so they don't go at exactly the same time with no back pressure. If your fluid is clean and the pistons move freely and with no leaks then your fine like jim said but none of us explaned how to tell.
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Old 02-27-2006, 08:15 PM
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That's not sticking. Sticking is being stuck.
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Old 02-27-2006, 09:34 PM
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I would think being stuck would be seized wouldn't it. Sticking is a sign of a problem, seizing IS a problem. If the piston doesn't move fairly free something is keeping it from doing so. That could include pitting, sludge or rust. I don't mean to say you can push it in with one finger but it shouldn't take great effort either.
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Old 02-28-2006, 09:24 AM
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Thanks guys. I think I am going to get a runout gauge tomorrow and see if one of my rotors is bent. Do you think it would be best to check this on the bike or remove the rotor and check it one a lathe?
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Old 02-28-2006, 12:01 PM
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Why are you checking your rotors, have you been feeling any pulsation in the lever? If you think it's nescessary then check it on the bike, it' wont sit exactly the same on a lathe.
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Old 03-01-2006, 10:59 AM
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either way is fine. You'll get a perfectly acceptable measure on the bike, but a lathe will be more accurate, but also more accurate than need be. You're measuring in thousandths.

If your rotor is within .001 of spec, you can try to mount it a different way on the hub. In that case it may be fine. Generally, the hub is spot on, though.
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Old 03-01-2006, 02:27 PM
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Re: Brake Caliper Rebuild?

If you check the runout while mounted on the wheel, then you are essentially checking the wheel as well. I have had brakes done before on a BMW. I gave the shop the whole wheel, and they took the brakes off to check them. No good! Turns out the problem was in the wheel, not the rotor.
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Old 03-01-2006, 04:25 PM
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Thank you Shayne, that was exactly my point. If you then find excessive run out take them apart to see which is the culprit.
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Old 03-04-2006, 01:21 AM
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Re: Brake Caliper Rebuild?

This knowledge was aquired after being a numnuts and riding off with the disk lock on.....

Ooops....
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Old 03-04-2006, 10:28 PM
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Re: Brake Caliper Rebuild?

[quote="superhawk22";p="17678"]
Originally Posted by shayne";p=&quot View Post
I used compressed air to pop the pistions out.
+1 to that.

For the first caliper I cracked it apart before loosening the calipers. Couldn't get the pistons out. My friend had a bike pump...

Ended up firing the piston into my forehead. That little sucker really packed a punch. Made a semi-circular cut like a cookie cutter.

Tie a rag over the caliper. Second caliper, remove the pads and fully extend the pistons before disconnecting the hydrolic line.
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Old 03-05-2006, 07:32 AM
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The idea is to put a thin board and a thick sponge inside the caliper when you blow out the piston.

Of course, if one piston is stuck, the others will pop out and that one will stay in. After splitting the calipers, you can usually grab it and twist it out. If it didn't need replacement before (it did) it'll sure need it then.
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