rear brake caliper issue

[hamish86]

Hi new to all this, but i replaced the rear brake pads the other day, had a right struggle to clean and get the new pads in so that they would fit around the disk, now the problem im having is that one of the pads are constantly rubbing on the disk, creating a lot of heat so im guessing this it not normal. When i tried to reset the pistons only the outer one would move back in while the other one did not budge (this is the side where the pad is constantly rubbing), is this normal?.i know i have to wear the pads in but i must have done at least 5-10miles since replacing and riding doesnt feel right atm. Any help would be appreciated. Cheers

[hamish86]

A

[darrsi]

Did you push the Pistons out a little and clean them up properly?

[hamish86]

I will re-check but i dont think it will go out anymore without popping out. Should that piston be moving?

[joebloggs]

You need to strip the caliper and rebuild it. I'd order a set of seals beforehand as your going to need them if not a set of piston's
Plenty of step by step video's on youtube

[darrsi]

I normally push them out another 2mm from where they were before so that a clean part is just exposed.
I'll get to work with a can of brake cleaner and a toothbrush to clean the Pistons as much as possible, then once done I'll smear red rubber grease around the exposed parts of the piston then personally use a g-clamp to gently push the Pistons back far enough to allow the new pads to fit.


The thing is, I do this at least twice a year and it keeps the caliper in good working condition.
If it's not done regularly then it either gets clogged up with brake dust or if there's no grease protection then there's a good chance you can get spots of rust, which can both cause a piston to seize up.


It does sound to me like you have a sticking piston, because once all cleaned up you should be able to put the bike on the centre stand and after pressing the brake lever the rear wheel should be reasonably free to spin.
With brand new pads you may get some rubbing initially as they bed in, which will actually take a bit longer than 10 miles to settle down, but if the caliper hasn't been cleaned regularly then I'd hazard a guess it is sticking. It won't be kind on the disc either, depending on what compound of pads you're using, so will need to be sorted sooner rather than later.

[limax2]

I will re-check but i dont think it will go out anymore without popping out. Should that piston be moving?

welcome to the site Hamish. Yes both pistons should be moving. If you clamp one piston and press the pedal the other should move out. In good condition you should be able to push each piston back in with firm finger pressure. Less firm pressure if the hydraulics are not connected.
The rear caliper pistons on these bikes are well known for sticking if not regularly maintained due to the exposed position below the swinging arm. I do mine once a year, but it doesn't go out on salted road and not in the wet very often. doing what darrsi has just described sounds good  .
You might get away with cleaning up the surface of the pistons after pumping them out as far as you dare short of right out. Otherwise it's a case of new seals and as joebloggs says possible new pistons. If it comes to needing new seals make sure you clean the grooves where the seals fit because it is the build up of corrosion behind the seal that can make the piston stiff to return.
A search on here will bring up plenty of advice on doing the job, but as always don't be shy of asking for advice.

[DaxPlusPlus]

If you do go down the route of cleaning the pistons I found this blog post very helpful .. helped me clean up the front brakes but ultimately I needed new seals for the rear second time around:


http://www.bikesandtravels.com/biker.aspx?ride=156&info=1

[darrsi]

Just from previous experience, don't go using any old degreaser sprays on brakes, there's one i've used before that i got from work and it left a residue on the pistons that doesn't really help matters at all.
Brake cleaner spray is very efficient at removing shite, leaves no residue at all, and also won't do any damage to the rubber seals. It's good stuff and designed for the job.


I'm sure it works okay but i'm not too keen on the idea of using brake fluid as a cleaner, like in the link DaxPlusPlus has given, each to their own but i simply wouldn't use it.
I will always use red rubber grease on the pistons as well, again not used in the video, but i ride as much as possible all year round so i do think it adds protection against corrosion at the very least, especially when the roads are salty during winter time.

[DaxPlusPlus]

Fair enough - I am most definitely learning when it comes to mechanics.


Next time I have a go at this I'll bear that in mind and give it a go with the brake cleaner/red grease instead. I use the bike more in the winter than the summer (long story) .. so anything that helps on that front is a bonus.


Thanks for the pointer 

[darrsi]

Forgot to mention, it's quite important to give your pad pins a good clean up with some wire wool.
Probably more so for the front ones, because if the pads can't slide properly then they can cause other problems too.

[Deefer666]

Just fit an FZS1000 one and have done with it

[Bretty]

I just took my rear caliper off. Which was a mission as It's a bit seized and wouldn't let go of the disk! I managed to drive the pistons out by standing on the lever but now they won't retract.

I'll take the pads out tomorrow and will hopefully get it moving with some cleaning.

I did the fronts and got them running great, then pushed in a couple of the pistons which made one pop out, dumping dot4 all over the place. So they'll need a top up and bleed, but even with air in the system they are still 10times better then they were!!!

[celticdog]

A timely post, good advice given by all!


I've just purchased these from fleabay


http://www.ebay.co.uk/itm/141680325587?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT


My bikes purely a commuter so I'm happy with budget pads    I use white spirit to clean calipers, so far I've not had any probs
with any of the seals.

[paulchucky]

Just fit an FZS1000 one and have done with it

as long as you look after things and clean as necessary at regular intervals theres nothing wrong with the rear caliper !