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Author Topic: cb550 caliper rebuild crappity crap  (Read 10362 times)

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Offline nilsey

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cb550 caliper rebuild crappity crap
« on: March 17, 2011, 11:38:45 AM »
About a month ago i decided to take some initiative and rebuild my front brake caliper, combing the best parts of the two calipers i had. the problem with the caliper on the bike was that the bleeder had busted off and i had no way to bleed the brake, although last fall it was working just fine.

So i took it all apart and substituted the caliper with the intact bleeder. put it all back together and bled the brake.

well i i finally got the bike fired up today and took her around the block. very, very poor front brake action, although it does squeeze a little (when the bike is almost at a stand still) there is not real braking action at any speed above 5 MPH.

i guess i have to take this all apart again and start over... anything i should be looking out for?
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Offline OldSchool_IsCool

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Re: cb550 caliper rebuild crappity crap
« Reply #1 on: March 17, 2011, 11:41:24 AM »
Does your lever pull into the grip without resistance at all or is it "spungy"?
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Offline nilsey

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Re: cb550 caliper rebuild crappity crap
« Reply #2 on: March 17, 2011, 11:45:46 AM »
Quote from: OldSchool_IsCool on March 17, 2011, 11:41:24 AM
Does your lever pull into the grip without resistance at all or is it "spungy"?

"Spongy." the bike stops with the front brake, but only when i'm rolling it slowly.
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1974 BMW R90/6

Offline TwoTired

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Re: cb550 caliper rebuild crappity crap
« Reply #3 on: March 17, 2011, 11:55:07 AM »
Still have air in the lines.

Have you read the brake FAQ?
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Offline nilsey

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Re: cb550 caliper rebuild crappity crap
« Reply #4 on: March 17, 2011, 12:10:56 PM »
Quote from: TwoTired on March 17, 2011, 11:55:07 AM
Still have air in the lines.

Have you read the brake FAQ?

yeah, two or three times. is there any section in particular you feel i haven't paid attention to?
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Offline TwoTired

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Re: cb550 caliper rebuild crappity crap
« Reply #5 on: March 17, 2011, 12:15:23 PM »
Yes,  ;D
http://forums.sohc4.net/index.php?topic=259.msg207521#msg207521

You should also check the small bleed hole is clear in the bottom of master reservoir.  If that's clear, the brakes will bleed themselves, given enough time.

Cheers,
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Offline nilsey

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Re: cb550 caliper rebuild crappity crap
« Reply #6 on: March 17, 2011, 12:18:52 PM »
twotired --- yeah,  I probably didn't exercise enough patience in the bleed process..... once more into the breech!
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Offline Spikeybike

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Re: cb550 caliper rebuild crappity crap
« Reply #7 on: March 17, 2011, 12:28:54 PM »
hey speaking of squeezing things that feel spongy....... TT you must bring back your previous avatar  ;D ;D ;D


and it sounds to me like you just didn't bleed them enough, if it's working (to at least some capacity) then i'd guess the rebuild was done right ..it's not rocket science after all  ....    bleed more..... my 550 is notorious for taking FOREVER to bleed all the way
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Offline OldSchool_IsCool

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Re: cb550 caliper rebuild crappity crap
« Reply #8 on: March 17, 2011, 12:53:08 PM »
Quote from: Spikeybike on March 17, 2011, 12:28:54 PM
hey speaking of squeezing things that feel spongy....... TT you must bring back your previous avatar  ;D ;D ;D
 

Agreed.  How else will we remember to check tire pressure regularly??
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Offline nilsey

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Re: cb550 caliper rebuild crappity crap
« Reply #9 on: March 17, 2011, 01:00:18 PM »
one thing about teh FAQ:

Quote
Close off the caliper bleed and wait a full minute. Go get a fresh cold one. Visit the rest room. Clean and put some tools away.

Vacuum the living room. Have a snack. Stare off into space thoughtfully.

Now go back and gently stroke the hand lever. Did you get more bubbles? Stroke gently until no more bubbles.

he doesn't mention re-opening the caliper bleed. does this mean the gentle pumping from this point on occurs with the bleed screw shut down?
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Offline nilsey

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Re: cb550 caliper rebuild crappity crap
« Reply #10 on: March 17, 2011, 01:06:46 PM »
And another thing.....

As i mentioned i my original topic post, between the initial rebuild/bleed and today's brake sponginess, we're talking about 4-5 weeks of time. wouldn't that have been enough for the brake to "self-bleed"?
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Offline TwoTired

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Re: cb550 caliper rebuild crappity crap
« Reply #11 on: March 17, 2011, 01:15:51 PM »
Quote from: nilsey on March 17, 2011, 01:00:18 PM
he doesn't mention re-opening the caliper bleed. does this mean the gentle pumping from this point on occurs with the bleed screw shut down?
Yes.  If the bubbles are near the top it is hard to push them all the way down to the bottom.  Better to let them out at the top.

Quote from: nilsey on March 17, 2011, 01:06:46 PM
As i mentioned i my original topic post, between the initial rebuild/bleed and today's brake sponginess, we're talking about 4-5 weeks of time. wouldn't that have been enough for the brake to "self-bleed"?
It should have improved... IF...  the master's bleed hole is clear.
There are two holes in the bottom.  One large and one is just a pinhole.  If that pin hole is clogged it can't self bleed.

Did you rebuild the master as well?
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Offline nilsey

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Re: cb550 caliper rebuild crappity crap
« Reply #12 on: March 17, 2011, 01:19:52 PM »
Quote from: TwoTired on March 17, 2011, 01:15:51 PM


Did you rebuild the master as well?
nope.
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Offline nilsey

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Re: cb550 caliper rebuild crappity crap
« Reply #13 on: March 18, 2011, 10:57:04 AM »
ugh. tried bleeding the brake again yesterday following teh FAQ instructions as closely as i could. i'm still getting only a very weak braking action.

i'm gonna have to take apart the caliper again, i'm afraid. i wonder if the caliper i substituted is juts no good.

to recap, what i did was:

- disassemble the caliper
- replace the "old" caliper with a broken bleed screw for the "new" (old) one with a functioning bleed scew. but teh "new" caliper didn't look particularly great on teh inside, i tried cleaining it out as best i could.
- reassemble and bleed.

i'm thinking i may juts go back to the caliper with teh broken bleeder. its a pain in the ass to bleed it but it worked.
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Offline Roach

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Re: cb550 caliper rebuild crappity crap
« Reply #14 on: March 18, 2011, 11:17:54 AM »
i don't think the problem is with your caliper!!!! they are very simple only 2 parts your seal and piston if its not leaking then its not it... you are getting some movement in it because you are getting a bit of friction on your rotor...buy a master cyclinder rebuild kit. and if you have the original brake lines go to SS.. ;)
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Offline TwoTired

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Re: cb550 caliper rebuild crappity crap
« Reply #15 on: March 18, 2011, 11:18:39 AM »
Have you verified that the master's tiny pressure relief hole is clear?
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Offline nilsey

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Re: cb550 caliper rebuild crappity crap
« Reply #16 on: March 18, 2011, 02:13:39 PM »
Quote from: TwoTired on March 18, 2011, 11:18:39 AM
Have you verified that the master's tiny pressure relief hole is clear?

When I squeeze the brake gently I see fluid coming up out if the left hole. That the one?
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1974 BMW R90/6

Offline TwoTired

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Re: cb550 caliper rebuild crappity crap
« Reply #17 on: March 18, 2011, 02:24:48 PM »
Quote from: nilsey on March 18, 2011, 02:13:39 PM
Quote from: TwoTired on March 18, 2011, 11:18:39 AM
Have you verified that the master's tiny pressure relief hole is clear?

When I squeeze the brake gently I see fluid coming up out if the left hole. That the one?


Yes, assuming it's your left as you sit on the bike and not facing it.
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Lloyd... (SOHC4 #11 Original Mail List)
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Re: cb550 caliper rebuild crappity crap
« Reply #18 on: March 18, 2011, 02:43:38 PM »
TT I like the eyeball can you PM me a copy .
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Offline SohRon

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Re: cb550 caliper rebuild crappity crap
« Reply #19 on: March 18, 2011, 02:44:53 PM »
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Assembling my '74 CB550: http://forums.sohc4.net/index.php?topic=86697.0
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Offline nilsey

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Re: cb550 caliper rebuild crappity crap
« Reply #20 on: March 18, 2011, 03:01:29 PM »
Quote from: SohRon on March 18, 2011, 02:44:53 PM

yeah i meant sitting on the bike, the left hand hole.

so, looking at teh photo above,  when i squeeze the brake i see fluid coming up out of teh right (smaller) hole and no detectable activity out of the left one. do i still need to rebuild the MC? it sounds like a PITA.

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Offline TwoTired

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Re: cb550 caliper rebuild crappity crap
« Reply #21 on: March 18, 2011, 03:38:52 PM »
I would think not.

Do you get a firm lever?

When you crack the caliper bleeder and pull the lever in, does fluid come out?

Do you release the lever while the bleeder is open?
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Lloyd... (SOHC4 #11 Original Mail List)
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Offline nilsey

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Re: cb550 caliper rebuild crappity crap
« Reply #22 on: March 18, 2011, 04:50:06 PM »
Quote from: TwoTired on March 18, 2011, 03:38:52 PM
I would think not.

Do you get a firm lever?

When you crack the caliper bleeder and pull the lever in, does fluid come out?

Do you release the lever while the bleeder is open?

firm lever? not really. i mean, its kinda spongey, but it does get firm at the end of its travel, almost at the grip. the brake piston does get some pressure, juts barely enough to stop teh bike when at a walking speed.

fluid does come out when i crack teh lever.

I'm not releasing the lever when the bleeder is open.

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Offline TwoTired

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Re: cb550 caliper rebuild crappity crap
« Reply #23 on: March 18, 2011, 04:56:21 PM »
What condition are the brake hoses in?
Are they in the stock arrangement?

Do you use the stock handlebars?
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Offline nilsey

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Re: cb550 caliper rebuild crappity crap
« Reply #24 on: March 18, 2011, 05:28:06 PM »
Quote from: TwoTired on March 18, 2011, 04:56:21 PM
What condition are the brake hoses in?
Are they in the stock arrangement?

Do you use the stock handlebars?

funny you should ask that as i was juts looking at that as a possible explanation. i have drag bars, and because of it the brake hose goes down from the MC, then rises slightly up, and back down towards the banjo bolt in the middle of the triple tree. is air collecting there perhaps?

conditon? ....old!  8).

i mean, the rubberized outside of teh hoses is showing wear, but i don't see any cracks or leaks.

might this be a good timeto replace the hoses with shorter onse? i swear the brakes worked juts fine at teh end of fall.... ;)

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