Author Topic: rear break: need your help!  (Read 5478 times)

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Offline Nurali

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rear break: need your help!
« on: June 17, 2013, 12:57:58 PM »
Hey guys, need another advice..
rear break had been acting strange..
It breaks, but cylinder inside the calliper doesnt move back to its place to release pressure. All is clean as it can be, in good condition.
MC mechanic cleaned both calliper and the main cylinder.
I ordered new repair kit for the main cylinder, but my mechanic is almost sure that its not that. He suggested to replace the breaking hose and since the pad grips are missing to get those too. (nr 5 on the picture, i think)
Yamaha dealer cant get those parts anymore.. Any ideas on where to get them or maybe aftermarket solutions?
And yeah, what do you think about this issue in general? does it sound right with replacing the hose? Cause I can't imagine that could do the trick..
Hope you can help..

Offline galagmosh

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Re: rear break: need your help!
« Reply #1 on: June 17, 2013, 01:42:06 PM »
Hi,

It could very well be the hose. I donīt know the correct term for it in english, but in swedish itīs called "hose separation", loosely translated.
Itīs a phenomena you also can get on tyres. It means that the rubber inside the hose loosens up and creates something like barbs (right word for it?) on the hose interior, that prevents the brake fluid to flow back properly. Since the pressure is much larger when you press the brake lever than when you release it and the fluid should go back from the caliper, it still brakes but leaves the brake dragging because the fluid is not pushed back enough.
I hope this explanation makes sense in my layman english  ;) :D

Improved spelling on this reply, ho ho...

Offline Nurali

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Re: rear break: need your help!
« Reply #2 on: June 17, 2013, 01:51:45 PM »
Hi,

It could very well be the hose. I donīt know the correct term for it in english, but in swedish itīs called "hose separation", loosely translated.
Itīs a phenomena you also can get on tyres. It means that the rubber inside the hose loosens up and creates something like barbs (right word for it?) on the hose interior, that prevents the brake fluid to flow back properly. Since the pressure is much larger when you press the brake lever than when you release it and the fluid should go back from the caliper, it still brakes but leaves the brake dragging because the fluid is not pushed back enough.
I hope this explanation makes sense in my layman english  ;) :D

Improved spelling on this reply, ho ho...

Thanks for quick reply galagmosh :)
Make sense what you're talking about!
Any idea if the break hose can be replaced with any other hose? My dealer cant get it anymore.. :)

Offline galagmosh

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Re: rear break: need your help!
« Reply #3 on: June 17, 2013, 02:34:12 PM »
I suppose any brake line will do fine, as long as youīve got the right dimensions on the banjo fittings. Correct me if Iīm wrong, but doesnīt the XS 500 use the same brake caliper as the XS 650? If so they should fit, and getting brake lines for the XS 650 is a breeze.

When I customized my harleys I always made my own brake lines. That not hard, and better than bying used ones on ebay or whatever, that soon could act up like the one yours probably do.
It getīs a tad more expensive but then again, you can customize it any way you want. I used to get parts for that from here:

http://www.bikeline.se/sv/artiklar/hjul-dack-bromsar/bromsar/kopplingar-slang/57-70/sida.html

Shop is based in Malmö, Sweden, but you can probably get parts from any good bike dealer.   

Offline Nurali

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Re: rear break: need your help!
« Reply #4 on: June 17, 2013, 11:16:15 PM »
wow, so much response!
Thanks so much, ill get to it one of the next days and keep you up to date with whats going on :)

Offline jimmer

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Re: rear break: need your help!
« Reply #5 on: June 18, 2013, 09:37:22 PM »
I responded in your general discussions post.

Offline CrouchyUK

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Re: rear break: need your help!
« Reply #6 on: June 18, 2013, 09:50:28 PM »
There's also a very similar thread about brakes on the XS500 Facebook page.....
1975 Honda CB200T (2) - 1975 Yamaha XS500B (2) - 1976 Yamaha XS500C
1977 Yamaha RD400D - 1977 Yamaha XS500D - 1978 Honda CB550K - 1980 Honda CB400N
1980 Honda CB900FA - 2000 Kawasaki ZX6-RG2 - 2002 Suzuki GSX-R1000K2

Offline Nurali

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Re: rear break: need your help!
« Reply #7 on: June 20, 2013, 02:04:38 PM »
There's also a very similar thread about brakes on the XS500 Facebook page.....

its mine too, i posted in both places to get most of input..

Offline guylr

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Re: rear break: need your help!
« Reply #8 on: July 17, 2013, 04:52:44 PM »
If the master cylinder is not releasing the pressure on the brake line then the problem is likely at the tiny bleed hole in the master cylinder bore. If that hole gets plugged it will hold the brake on. If the brake is held on it will overheat the fluid and increase the pressure even more until the brake locks. I've seen it a lot over the years. The fix is to clear the obstruction in the hole or replace the master cylinder.

Guy
« Last Edit: July 23, 2013, 12:22:11 PM by CrouchyUK »
Now Retired Yamaha guy. Cut me and I bleed "Cinquasia Red"

Offline glennre5

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Re: rear break: need your help!
« Reply #9 on: August 01, 2014, 09:21:09 PM »
Well to save making a new post my bike has now the same problem ....not releasing the pressure and the back  brake starts to lock up ..Have striped the caliper again and checked the hose but am sure its the master cyl ...Have a spare but leaks so looks like a overhaul job ....

Offline CrouchyUK

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Re: rear break: need your help!
« Reply #10 on: August 01, 2014, 09:34:11 PM »
Hmm..  So with the brake binding- if you crack the bleed nipple or a banjo fitting- does the wheel then free up?
1975 Honda CB200T (2) - 1975 Yamaha XS500B (2) - 1976 Yamaha XS500C
1977 Yamaha RD400D - 1977 Yamaha XS500D - 1978 Honda CB550K - 1980 Honda CB400N
1980 Honda CB900FA - 2000 Kawasaki ZX6-RG2 - 2002 Suzuki GSX-R1000K2

Offline glennre5

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Re: rear break: need your help!
« Reply #11 on: August 01, 2014, 10:14:15 PM »
Yes !! open the bleed nipple and its free ....Just to add the piston will not push back using gas pliers .....

Offline CrouchyUK

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Re: rear break: need your help!
« Reply #12 on: August 01, 2014, 10:43:01 PM »
Fair enough- follow Guy's advice then.

If the caliper stayed locked with the hydraulic pressure released then I was going to suggest investigating the "float" of the caliper.  I've had 2 instances this year of rear calipers locking on because the caliper would not move back across.  Both cases were because PO's had lubricated the rubber bush (Item 6 in the diagram above) with Copaslip or similar.  The boot swells up and caliper will no longer float.....
1975 Honda CB200T (2) - 1975 Yamaha XS500B (2) - 1976 Yamaha XS500C
1977 Yamaha RD400D - 1977 Yamaha XS500D - 1978 Honda CB550K - 1980 Honda CB400N
1980 Honda CB900FA - 2000 Kawasaki ZX6-RG2 - 2002 Suzuki GSX-R1000K2

Offline winslowtaft

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Re: rear break: need your help!
« Reply #13 on: August 01, 2014, 11:06:29 PM »
Just ran into this problem myself and it was due to a plugged bleed port in the master as mentioned previously. Took some time to figure it out and a sewing needle to finally get it clear. Even clean it still seems to drag more than my other bike, but never gets worse than the initial slightly heavy drag or locks up.

To check this you need to disassemble the master cylinder completely. remove the bolt from the horizontal bore and shine a light up through the master cylinder bore. if you don't see two small holes (when viewed through the horizontal bore) then one is clogged. see the images below. To clear the clog, I stuck the sewing needle in the eraser of a pencil and very delicately drilled out the clog. Good luck!

Offline glennre5

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Re: rear break: need your help!
« Reply #14 on: August 01, 2014, 11:10:59 PM »
Thanks for that ....Will keep the post updated on the problem ..