How to diagnose sticky brake piston?

[Jamieg285]

I'm new to bike mechanics, so am looking for some advice.

I've not ridden for a number of years and have had my Fazer for a couple of weeks now. To me it appears that the back brake is weak, and from reading on here out might have a sticky piston.

I want to know how I can confirm this, without having to strip it down too much. I need the bike to be useable, so can't take things apart unless I have the parts to put back again. If it's knackered and I need seals, pistons etc. I'd rather keep the money and put it toward a blue spot caliper.

Also, what's the average price for the caliper these days?

[darrsi]

This is a simple one just for starters, get some degreaser spray, or i s'pose even WD40 (just avoid overspray on rear disc), and clean out the joint of the rear brake foot lever.
I clean mine every few months and really notice a difference when it's done.
I normally use the spray then oil or grease it back up afterwards.
It tends to get clogged up quite easily as i ride in all weathers, and if you haven't done it before it could cause a spongy feeling.
Definitely worth 2 minutes of your time......
 

[Fazerider]

I usually get by with undoing the two bolts and wriggling the caliper off the disc. Free the pads, then you can get in there with an old toothbrush and WD40 and I normally find that, with a bit of pushing pistons in and out, that I can get it moving smoothly again without actually removing pistons.. this saves the hassle of bleeding air out of the system.
Replacement (OE) pistons and seals looks like about £45, seals alone a good bit cheaper.
A blue spot will be around £50 s/h, of course you'll need pads too... and since it's bound to be a bit of unknown quality, you'll probably want to change the seals on it. Advantage is, of course, you can do all that work in advance without having the bike out of action.

[topgun44]

 and some thing to think about the back brake on old fazer are very weak as well so you could be waste u time and live with it like i do 

[red98]

and some thing to think about the back brake on old fazer are very weak as well so you could be waste u time and live with it like i do 

 
ah yes...iam with you TOPGUN.....saying that though if the bikes new to you it would`nt hurt giving it a good going over and a clean 

[limax2]

A quick test of the back brake. With the bike on the centre stand spin the back wheel and see if there is excessive drag. There will be some drag due to the drag from the chain but you should be able to turn the wheel easy enough and with a good push get about one full turn of free rotation. Next apply a small amount of pressure onto the brake pedal with your right hand while turning the wheel with your left hand. You should feel the brake starting to bite with light pressure on the pedal. It shouldn't take much pressure on the pedal for you not to be able to turn the wheel at all with the other hand.
Due to the position of the caliper it catches a lot of road spray so does need a bit more maintenance than might otherwise be the case.

[darrsi]

Do what 'limax2' says and if the brakes start singing out loud #"I am what i am..."# then you've definitely got a bit of drag...... 

[know your limitations]

I would add that if the piston is sticking and the pads aren't releasing correctly, the prolonged contact would produce increased friction which, in turn would generate heat. Even after a short ride, if the rear disc is too hot to touch for more than a couple of seconds, that's a sure fire indication that something is amiss.

[Jamieg285]

Ok, had a proper look today. Inner piston was slightly corroded and was sticking. Pushed both out a bit and cleaned them up as suggested. Made an immediate difference, but I think I should carry on and do the job properly, or replace the caliper.
 
I wasn't sure about the pad retaining pins though. I don't know what they should look like, but they both appeared worn where the pads would sit. I assume that this isn't right and the pins should be a consistent diameter down the full length, and would therefore need replacing. Problem is I've not been able to find anywhere online that sells them to compare against. Can anyone tell me if this is normal, or if I should get new ones, and where I can get them?

[darrsi]

Just clean the pins up for now and put a light smear of copper grease on them.


And purchase some 'red rubber grease' to put on the exposed parts of the caliper pots, to try and protect them from future corrosion. You can buy it in small pots, or even very small sachets.

If you wanna buy new pins then http://www.fowlers.co.uk/  is the place, it's where to buy most original parts from. (They always ask for your chassis number, and NOTHING is inexpensive)

I recently bought front pad pins on Flebay, and didn't realise that they fit a few other calipers from what i could make out, they were almost a standard pin so when i measured them sure enough they were the same.

I'm not sure about the rear ones though because of the thread but this is the place i bought them from, maybe email them, ring them or just measure yours and see if they match? (DISCLAIMER: I'm just putting you on their web page, i've no idea what size pin you need so don't just go and buy it without checking first?)

http://www.ebay.co.uk/itm/Tokico-brake-caliper-pad-pin-Kawasaki-Suzuki-Honda-Yamaha-52mm-x-5mm-/150747444917?pt=UK_Motorcycle_Parts&hash=item23193f76b5#ht_3916wt_1067