Rear Brake Servicing

[Middy2000]

Just had an MOT and got advisory for the rear caliper sticking.  To my knowledge it's never been serviced.

Looking for advice on this. Not competent to do it myself and don't want to go down the wrong path.

There are places online advertising a refurb service of between 50-75 quid.  Not sure how detailed they go.
Should I change the pistons even if they look ok?
Are the kits available online any good?
Anybody on here do them as a project?
Should I change the pads at the same time?

Etc...

[darrsi]

If it's an advisory you could probably get away with slightly pushing the piston out about 3mm with the brake pedal (no more than that), giving it a good clean with a toothbrush and brake cleaner spray (nothing else), putting Red Rubber Grease on the exposed piston, and also cleaning up the pad pins so the pads can slide easily.


One of those things that sounds very straight forward, and it is, but only after you've done it a couple of times.


I clean mine twice a year, and regrease them, and they function really well.
A little time consuming at first, especially the front calipers, but well worth it and also satisfying that you've done it yourself.


You only need to change the pads if they are worn down or in poor condition.


I prefer to use SBS Ceramic pads on the rear as they aren't as dusty as some others.

[Middy2000]

I'm not convinced I've the technical confidence to do that Darsi.

Assuming you unbolt the caliper and pull it away from the bike before gently applying pressure on the pedal?
Do you remove the pads or can you get access to the pistons?
Do you then prise the pads apart to refit?

When the bike was serviced they did say the pistons looked ok so I'm assuming the issue is with the seals ?

[darrsi]

I'm not convinced I've the technical confidence to do that Darsi.

Assuming you unbolt the caliper and pull it away from the bike before gently applying pressure on the pedal?
Do you remove the pads or can you get access to the pistons?
Do you then prise the pads apart to refit?

When the bike was serviced they did say the pistons looked ok so I'm assuming the issue is with the seals ?

I hear you, it's a daunting task first time at anything when you're not sure of what you're doing.


I'll see if I can find a video explaining things more visually.


There are two bolts holding the caliper on, and two smaller bolts (pad pins) that secure the brake pads in place. Once the pad pins are removed the pads will drop out. (do not over tighten pad pins when refitting, or they will chew up the caliper thread)

[fazersharp]

Do you have to put a thin bit of wood in between the pistons, otherwise is there a possibility of the pistons compleatly popping out.

[darrsi]

Do you have to put a thin bit of wood in between the pistons, otherwise is there a possibility of the pistons compleatly popping out.

If you pump the rear brake pedal gently enough they will slowly come out a bit at a time. But if one piston slides out much easier than the other then i use some small G Clamps that i bought just for this job, to stop the pistons being pushed out any more.
The front calipers are more fiddly as there are 4 pistons to keep control of.


Bear in mind i'm on about cleaning them up in situ, avoiding the need to mess about with bleeding the brakes. I normally clean mine up around now in Spring time when the weather takes a turn for the better, and also as near to winter as i can get that's still a warmish day for me to sit outside to do it.
To be honest though, once a year would be enough for my bike, it just depends if i have any spare time on my hands but the bike does sit outside my workplace in all weathers all year round so it's always good to keep them maintained.

[midden]

Not sure whether you've been told but the way to check for brakes binding is with wheel off the ground, actuate the brakes hard for approx 4 seconds release and immediately try to spin the wheel if they are binding there will momentarily be resistance. Best to have hold of the wheel before releasing the brake


I wouldn't and don't use red rubber because 1. it would attract crap to stick    2. according to my Yam dealer, too much can have a negative impact on the seals and should only be used sparingly to help initial installation and whether or not that is the case  3. the brake fluid lubricates the piston anyway.


Before removing the pads i push both pistons fully in then remove pads and clean the caliper with a tooth brush. put a spanner between the slot and then a wedge between the spanner and one of the pistons so that I can pump one piston out at a time to clean. 


Once cleaned if they are still binding a bleed may finish the job

[jul1us]

Servicing a sticking caliper was basically the first thing I ever did on a bike and is what got me into doing stuff myself. Basically, I bled the caliper, took it apart and gave it a good clean.


When I recently bought my FZS 1000 the front callipers were also sticking, so I did the same.


In my experience nothing needs replacing. Even the seals were in great condition in both cases, you just have to remove them carefully. In both cases it was crud sticking to the pistons, so mainly they needed cleaning.


If you are inclined to try it yourself, they are loads of good videos on YouTube. It's a pretty easy job but a bit messy.


And if you want to keep it simple, here is a good video, how to clean them without taking them apart:


https://youtu.be/iFd-eJkxqVo

[darrsi]

Not sure whether you've been told but the way to check for brakes binding is with wheel off the ground, actuate the brakes hard for approx 4 seconds release and immediately try to spin the wheel if they are binding there will momentarily be resistance. Best to have hold of the wheel before releasing the brake


I wouldn't and don't use red rubber because 1. it would attract crap to stick    2. according to my Yam dealer, too much can have a negative impact on the seals and should only be used sparingly to help initial installation and whether or not that is the case  3. the brake fluid lubricates the piston anyway.


Before removing the pads i push both pistons fully in then remove pads and clean the caliper with a tooth brush. put a spanner between the slot and then a wedge between the spanner and one of the pistons so that I can pump one piston out at a time to clean. 


Once cleaned if they are still binding a bleed may finish the job

I totally disagree about the red rubber grease.
It certainly doesn't do anything negative whatsoever otherwise I would know about it by now.
And you say it attracts crap. Yes indeed it does, but that crap stays on top of the grease and doesn't touch the pistons. Many times I've gone to clean them and they look covered in dust and all a bit grotty, which will happen anyway if you ride in all weather's, but what I've found is that underneath all that crap the pistons were totally clean and protected from the elements by the grease. A few sprays of brake cleaner and a scrub with a toothbrush and they all look like new again. I only serviced mine again two days ago and sure enough they were in very good nick as usual. They appreciate the clean of course, but none were seizing up at all, and even the slightest touch of the brakes going to work today was extremely responsive and instant.
Mustn't overlook the pad pins either, they need properly cleaning up so the pads can slide freely, because if you neglect them and you get hints of rust then more problems will arise.

[robbo]

Totally agree with darrsi’s reply

[Trebus]

I would also add that changing the seals is sometimes needed, even if they look ok.

Front blue spots on mine were sticking, cleaned them by popping pistons and into the seal grooves etc. A few months later they were sticking again. New seals and it was perfect. Didn’t appear to the naked eye that they’d expanded but new seals was the fix.

On the flip side, I’ve many times stuck the old seals back in on other machines and worked fine.