Author Topic: Cb550 front disc brake (Read 9943 times)

Anthub · « **Reply #50 on:** November 12, 2017, 05:40:00 AM »

Yeah... I can press it in using my thumbs

.. There’s a bit of resistance but it goes in

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strynboen · « **Reply #51 on:** November 12, 2017, 05:40:16 AM »

have you tryed to vaccum fluid aut thrug the caliper air nippel-(may i vrite that)?..somtimes vaccum can suck the bubbels dovn better then they vork themself up..your costum lines is different then stock ..so can give some air traps..can you loan a vaccum car type one..to try that..

Anthub · « **Reply #52 on:** November 12, 2017, 05:44:55 AM »

Yeah, I’m sure I could get my hands on one ... thanks for the advice

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Deltarider · « **Reply #53 on:** November 12, 2017, 06:30:45 AM »

What helped for me when I had some air left in there, was: remove tank, remove battery and lie bike on its left side for an hour or so, then upright the bike and the problem was solved.

Anthub · « **Reply #54 on:** November 12, 2017, 06:32:34 AM »

Right!!! That could be one of my last resort options

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Deltarider · « **Reply #55 on:** November 12, 2017, 06:34:03 AM »

Just let the laws of physics do the work for you.

Anthub · « **Reply #56 on:** November 12, 2017, 06:37:45 AM »

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seanbarney41 · « **Reply #57 on:** November 12, 2017, 10:18:18 AM »

can you pump up more pressure by repeatedly and rapidly squeezing the lever?

I have often found the only way to get all the air out is by actually riding the bike in a safe area. Apparently, bumps and vibrations are gonna help you out here.

Anthub · « **Reply #58 on:** November 12, 2017, 10:35:44 AM »

No... the pressure remains the same no matter how much I pump the lever.
I took the bike over to a nearby trading estate this morning and tested the brakes out without the fear of someone going into my backend... repeatedly accelerating and braking.The front brake is really bad. Much better braking when combined with the rear but even the rear isn’t great.. I certainly can’t get anywhere near to locking the rear tyre up.
I got home and put another litre of fluid through the system but nothing has changed. I checked the piston at the lever end following the MC rebuild to see if there were any leaks but it was dry.
Strange thing was, during bleeding, when the bleed nipple was shut, when I pulled the lever, a burst of small bubbles came from the left hand hole in the reservoir whereas the only bubbles had been coming from the right hand hole previously.
Once I’d stopped bleeding, after a short period of time, the bubbles then re appeared from the right hand hole when operating the lever.
Really appreciate all the advice from everyone by the way

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Stev-o · « **Reply #59 on:** November 12, 2017, 10:43:14 AM »

I'm beginning to wonder if the issue is the master cylinder? I know you rebuilt it but it may have pressure issues...

Anthub · « **Reply #60 on:** November 12, 2017, 10:56:21 AM »

Yeah.. maybe. I’m no expert by any means but I can follow instructions and put it together as per this on YouTube...

As I’ve said, there doesn’t seem to be any leakage at the piston end of MC, nor the banjo end so I can’t work out where these constant bubbles are appearing from

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seanbarney41 · « **Reply #61 on:** November 12, 2017, 11:01:05 AM »

and you do realize that these brakes do really suck even when they operate as originally intended...

Maybe you could try a known good master cylinder from another bike?...it doesn't have to be from the same model bike

Anthub · « **Reply #62 on:** November 12, 2017, 11:13:36 AM »

Yeah, I’m sure 40yr old disc technology isn’t great but as I’ve been told on here, I shouldn’t be able to push the bike forwards with the front brake fully on... and I shouldn’t be able to pull the lever right to the grip.
I’ve got the winter to sort it out

so I’m sure I’ll get there. On a positive note, I’m learning new stuff all the time and getting to know the bike. I’ve been away from biking for around 12years now, having ridden sports bikes until kids came along. This bike was a retirement present to myself and although I love the look of it (I’m sure some would disagree

) I’m finding quite a few issues with the mechanicals and electrics

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Stev-o · « **Reply #63 on:** November 12, 2017, 11:58:21 AM »

Quote from: Anthub on November 12, 2017, 11:13:36 AM

I shouldn’t be able to push the bike forwards with the front brake fully on... and I shouldn’t be able to pull the lever right to the grip.

Correct. And the rear brake should lock up the rear wheel...

Anthub · « **Reply #64 on:** November 12, 2017, 12:00:12 PM »

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TwoTired · « **Reply #65 on:** November 12, 2017, 08:02:07 PM »

In the stock position, the caliper brake line is at the very top of the caliper. This is where bubles would rise and get into the line. With it canted, air can be trapped.

Also in stock configuration, air in the caliper has an unobstructed rising path all the way to the tiny bleed hole. There are no loops or "ceilings" to hold air from rising. If you wait, the stock arrangement will actually self bleed.
Since your configuration is stylized, rather than arranged in functional form, step back and look at the caliper, lines, and the pathway a bubble would have to take to get to that tiny hole in the mc. If it can't rise naturally against gravity, either reroute temporarily to allow rise, reposition the mc, or the whole bike to allow natural bubble rise in the hydraulic system

Cheers,

Anthub · « **Reply #66 on:** November 12, 2017, 10:52:11 PM »

.. thanks for that

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RAFster122s · « **Reply #67 on:** November 13, 2017, 02:40:33 AM »

Unless you wish to retain that look...how much effort to return the brakes to the stock configuration by swapping forks side to side and returning the swingarms for the caliper to their stock leading configuration? It should bleed normally then.

Yes, I am leaning towards a bad caliper too.

David

Anthub · « **Reply #68 on:** November 13, 2017, 03:48:21 AM »

Yes David... I actually woke up this morning thinking that’s what I’m going to do. It certainly doesn’t bother me about the ‘look’. Can’t understand why it was done in the first place if it has a detrimental effect on braking efficiency.
I’m also wondering, with it having clip on’s, should I rig up a ‘flat bar’ for the bleeding process so that the MC is sitting in a more horizontal position?

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DaveBarbier · « **Reply #69 on:** November 13, 2017, 04:56:04 AM »

I don't think it's detrimental to braking, just not an upgrade.

When I bleed I have the bike on it's side stand and bars full lock left. That raises the right bar and makes the master cylinder parallel. I believe my clipons are 7° down turned.

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Anthub · « **Reply #70 on:** November 13, 2017, 04:57:52 AM »

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Anthub · « **Reply #71 on:** November 13, 2017, 04:58:19 AM »

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Anthub · « **Reply #72 on:** November 13, 2017, 04:59:06 AM »

Swapping the forks round now

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CBGhia · « **Reply #73 on:** November 13, 2017, 08:36:33 AM »

Here are some Master Cylinders for sale, if you need another one.

http://forums.sohc4.net/index.php/topic,169363.0/topicseen.html

Anthub · « **Reply #74 on:** November 13, 2017, 10:35:57 AM »

Thanks ...

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Author Topic: Cb550 front disc brake (Read 9943 times)