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Brake lever playing up

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muttley1
the 900
the 900

Posts : 763

Brake lever playing up

Post by muttley1 on Wed 08 Feb 2017, 3:09 pm

Wonder if anyone can give some advice on my front brake issue? Use the thing normally or when braking harder, all fine. However, when braking gently e.g. slow filtering, the lever goes all the way back to the bar, let it go and brake again and all is fine.

This was a prob a couple of years back but settled down after new master cyl kit, brake bleed, new piston seals and general overhaul. Now its back so any pointers towards fixing it appreciated.

The only thing I can think of is the little metal washer/thing in the master cylinder itself, maybe its impeding the movement of fluid?

Btw master cyl is nissin, caliper is brembo, same as on my other bike, the setup is working fine there.

cheers


muttley1
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hh_12345
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Re: Brake lever playing up

Post by hh_12345 on Wed 08 Feb 2017, 3:42 pm

I've found a webpage that describes it:

http://www.tegger.com/hondafaq/mastercylinderreplace/

It suggests worn master cylinder seals.
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Jameshambleton
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Location : Bedale, North Yorkshire

Re: Brake lever playing up

Post by Jameshambleton on Wed 08 Feb 2017, 5:51 pm

@hh_12345 wrote:It suggests worn master cylinder seals.

Not what I wanted to hear, mines been doing the same since my pads have been getting low.

muttley1
the 900
the 900

Posts : 763

Re: Brake lever playing up

Post by muttley1 on Thu 09 Feb 2017, 9:59 am

Thanks for the replies.
Master cylinder kit is 2000 miles old at most, pads are 1000 miles in so its a mystery. All I can think of doing is to take out the master cyl kit, check for any gunk or damage to the piston/seal in there and use a pin to see if there's any gunk in the little hole between the bottom of the master cyl and the hole the piston goes along.
Messy ol' job for a rainy day then.

muttley1
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wornsprokets
the 900
the 900

Posts : 1257
Location : dublin

Re: Brake lever playing up

Post by wornsprokets on Thu 09 Feb 2017, 10:32 am

Have u braided line on caliper... i took mine off to do front wheel bearings i put caliper on top of mud guard... when i put caliper back on i lost pressure it went to bar...

muttley1
the 900
the 900

Posts : 763

Re: Brake lever playing up

Post by muttley1 on Thu 09 Feb 2017, 6:09 pm

Yep, I've braided hose fitted. I've bled the brakes through a few times and left the lever cabletied on overnight to force out any remaining air. Doesn't make any difference.

muttley1
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wornsprokets
the 900
the 900

Posts : 1257
Location : dublin

Re: Brake lever playing up

Post by wornsprokets on Thu 09 Feb 2017, 6:45 pm

Thats strange.  I put mine on muguard on its side, then put back on and it went to bar...  then i bled it a little i was running out of time.. i put cable tie on it back to bar.. i went off for couple hours came back couple pumps of lever. .and pressure came back  fully after about 10 pumps of lever ....my cousin works on lot of race cars he says its happened to him with braided lines taking off calipers ....
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eternally_troubled
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Location : 'ere be fens. (near Cambridge)

Re: Brake lever playing up

Post by eternally_troubled on Fri 10 Feb 2017, 4:42 pm

I suspect the master cylinder seal has 'gone' again - if it was air in the system the sponginess would be there all the time irrespective of how you use it.

It's certainly worth taking it apart and having a good look/clean - it can't really do any harm. The master cylinder is pretty good (IME) at collecting grime/rust under the big black rubber dust cover so it is possible some of this has got inside and is screwing things up.

muttley1
the 900
the 900

Posts : 763

Re: Brake lever playing up

Post by muttley1 on Thu 16 Feb 2017, 7:04 pm

This is a tentative "solved" pending things settling down.

I changed the fluid today and took out the master cylinder piston etc for a clean up. I also used a pin to check no gunk in the little hole in the bottom of the master cyl.

I noticed that on my other cb5, which also has a nissin master cyl the brake levers are much more solid looking. Whilst they fit the design seems a fraction different, it is bulkier where the lever joins the master cyl, so less play.
Anyway, found a brake lever like this in my box of bits and it's on now, All working consistently, will see how it goes.

muttley1

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