Rear Brake Issues

[Pezz]

OK so a couple of weeks ago got to work [4 mile ride] and as reversing the bike to park it noticed the rear brake was grabbing slightly. Didn't completely make stop the bike but made it harder to maneuver. On the ride home it was fine to start with but completely seized just as I was getting there. I had a look that weekend and the rear brake was really really dirty - I took it to a man who can as I am a man who cannot. The caliper was taken to bits cleaned and new pads put in - EBC bled etc. All good till this morning when it grabbed again upon getting to work - I went a longer route to work today [8 miles]. I patted the rear disk and it was really hot. I've been trying to ride slightly differently to how I was taught and use the rear less - only passed test 5 weeks ago - it was drummed into me the drag the back brake on slow corners and coming to stops trick - I've been using it less in fact at times not used it at all on rides but still obviously want/need it available and deffo don't want seizing under any circumstances ;)


Wondering if anyone had any idea's - the obvious clean and news pads being addressed already - I wondered if the disk may be warped and is rubbing a little and then the few times the brake is used during a 4 mile ride is enough to get it over heating and then the issue is compounded.

[DrD]

might be not enough play at the master cylinder - similar symptoms to others
Easily rectified - give it more slack at the brake pedal

[Sirc]

it really does sound like above post is the solution particularly as someone 'who can' has totally stripped and checked the caliper

[Mr Gazza]

Yup...What they said.

I had exactly this problem when I came home from my first MOT after fettling the Monster.

I had adjusted quite a lot of free play out of the pedal to get a nice instant response from the brake, leaving what I thought was enough free play ( about 2mm at the adjustable stop screw).

Mine nipped up to the point of not being able to move the bike forward or back at all a couple of times inbetween cooling off. I pushed it a bit too far the last time and made a thick black "S" shape in the road.

Everything has been fine since I backed off the adjuster, I just live with a little more pedal travel than I would usually have..

[Flip]

Definitely what the others have said- if you have to take it to a 'man that can' to make the adjustment don't let them rip you off- it is a two minute job!!

To be honest I would have thought that the 'man that can' who stripped the caliper would have checked the adjustment afterward so maybe he should do it for free as he didn't cure your problem (?).

Alternatively, perhaps he's actually a 'man that likes to think he can but can't' (?) and maybe there is someone from here near you that may be able to twiddle some spanners??

[utopia]

I agree with the above, but.....

Lack of adequate free play can be the root cause of the problem, but it could just be part of a wider picture, viz.....
If there is air or moisture in the system, this can expand when it gets hot due to normal brake use, thus eliminating the existing free play and causing consequent excessive drag, resulting in further overheating and expansion, and so on until the system locks up.
So, even though there may be free play when the system is cold, it may disappear when the system heats up.
Did your "man who can" use new brake fluid from a sealed container, or older stuff which may have absorbed atmospheric moisture over a few months in a half full container on the shed shelf ? Brake fluid is hygroscopic, ie it likes to absorb moisture. This turns back to vapour and expands massively when it gets hot.
I guess the same thing can happen, but to a lesser extent, with dry air in the system, so it might be worth bleeding the system again.
BUT ALSO .... I fitted EBC pads in my rear caliper a while back, and since then I've noticed the rear disc getting unusually hot, but without any sign of lock-up. It may have been getting hot with the old pads ....I dunno, I didn't check.....but it could also be a trait of the EBC pads.

[Nickj]

The sintered HH EBCs are a bit on the hard side. They're just OK for the front end if you are a fast rider but too hard for the back I think.

[Pezz]

thanks guys - I'm off tomorrow so will have a look at adjusting the free play fingers crossed it's simply that. Whilst not being confident enough to take pistons etc out of a calliper for a clean I'll be fine adjusting the pedal. I also forgot to mention that the fluid was checked and moisture content was only 1% which I believe is within ok limit so shouldn't be that

[utopia]

..... I also forgot to mention that the fluid was checked and moisture content was only 1% which I believe is within ok limit so shouldn't be that


Blimey !
How does one go about checking that then ?

I find that you can feel the free play quite effectively (on my M750) by jiggling the piston rod.
I'd be inclined to do it both before and immediately after a run, ie when cold and when hot, and see if you can detect any difference between the two.

[Pezz]

[QUOTE=utopia;467483]Blimey !
How does one go about checking that then ?[/QUOTE

with a brake fluid checking meter like this one ;)


http://www.amazon.co.uk/Brake-Fluid-Tester/dp/B005HVG4GQ/ref=sr_1_1?ie=UTF8&qid=1381224033&sr=8-1&keywords=brake+fluid+tester