1st Front Brake Pad Change

[Ingah]

I've taken the front pads out of my CB to change them, having just fitted a new (or shall we say, "nearly new") disc. I noticed both when getting the pads out, and pushing them back in to help push the pistons back into the caliper (? - Just following my Haynes), that it's a very very tight fit. This was yesterday, then it got dark and i came in.

Thinking about it though, the new pads are much thicker than the old pads (obviously), so how am i going to push these new pads in as the old ones barely fit in the gap? (at the very least, they were a real pain to remove - lots of yanking with grips).

The Haynes does mention about removing brake fluid via the master cylinder resevoir, but it's not clear if this is what will make the gap wider, or not.

[Martyc]

Squeeze the pistons back in with water pump pliers, large mole grips etc. On cars I use a g clamp but it's far too big for the caliper on my 'ped. Make sure that there's enough room in the master cylinder for the fluid to go into that's displaced. that's my method anywho.

[eastanglianbiker]

another way to help move the pistons back in is to loosen the bleed nipple make sure you fit a tube of some kind on it as it will squirt fluid out as you push pistons back into the caliper fit new pads remove master cylinder top and check fluid level as you gently pull brake lever to push pistons out onto the pads

[NC24]

Squeeze the pistons back in with water pump pliers, large mole grips etc.

 

That's one way to fubar the pistons and seals because the pistons won't retract square to the socket - you're only adding pressure to one side.

A much better method is to use a drift, such as a piece of tile batten timber, that is larger than the diameter of the piston. Push down on one side of the batten and tap the other with a deadblow mallet.

[Ingah]

Right, i've actually done the job (including lots of brake cleaner and toothbrushing the pistons as i was pushing them in), then tried to go to work on the bike. And instead of working as expected the brake is binding so i couldn't go, which tells me i haven't done it right (or that the caliper has somehow seized now, as it was incredibly hard to retract the pistons - took much pressure with a G-clamp, but i'm conscious that the brake wasn't binding at all before i changed the pads...) I was struggling to work out the orientation of the pad spring, but aside from that i can't think what else i could've really done wrong. It seemed so simple. Haynes seemed to think it was only 2 spanners! (difficulty)

This is a pain as i need the bike for work, and i don't have the parts required to strip the caliper (besides which, if i can't even do a simple pad change without incident, i'm half-afraid of opening up the caliper as there's much more i could mess up then).

So anyone remember back to their 1st pad change and might be able to suggest to me what newbie mistake i could've made?

Image of CB500R front brake caliper.

[eastanglianbiker]

did u grease up all the pins that the pads slide on and that the caliper might slide on i normally copper grease them

[Ingah]

Had a feeling you might respond eab, cheers

Took it apart again (i seem to spend my life taking parts of my CB apart repeatedly )

Noticed a few bits and bobs (including there not being any grease left on the pad pin, despite having put some on - must've been rubbed off when i put it through the hole) - but i thought the most important one by far was that one of the pistons (the one furthest from the hose) was coming out a tiny bit, then sticking into place whilst the other continued to come out. It was always at the same point. It wasn't like that before

Only way to get this sticking piston to come further was to use the old pads and a G-clamp to prevent the freely moving piston from going anywhere, whilst squeezing the brake lever. Despite brake cleaner, a toothbrush, plenty of WD40 through the edge of the piston/caliper, and eventually (when i noticed that there were far more hard deposits on the seized piston than the other), a small flat bladed screwdriver, removing the deposits down to small patches, it's still sticking - possibly a little less stiff, but requires the other side holding down to move more.

I've been told on another forum this means i probably have to strip the caliper. Which is a shame, because it means further time off-road whilst i await parts.

[rennie]

you need to strip the caliper!

It's not hard, just a bit fiddly

[Ingah]

you need to strip the caliper!

It's not hard, just a bit fiddly

 

Hehe, exactly what i heard said about replacing the front brake pads in the first place

[Guest]

What i do is when i remove the old pads, pull the lever a very small amount to push the pistons out slightly, use brake cleaner etc and a soft tooth brush and brush round the full circumference of the pistons, so that there is no much, grit, dirt etc etc around the pistons at all, wipe and dry around the pistons and apply copper grease. Slowly push the pistons back in and your done.

If the pistons wont move back in, keep cleaning etc and repeat the procedure. If they're rusted etc though you'll be needing new pistons.

Hope this helps!

[eastanglianbiker]

if you do strip the caliper down and replace the seals when u pull old seals out make sure you get the groove that the sela sits in perfectly clean as there will be lots of druv built up thats what stops piston most of the time.might be worth while popping piston out take seals out clean up behind them replace seals polish piston up use correst red brake grease on piston and put it back in

[Ingah]

Oh boy, now i've had it (and no one's open at this time of year and the post is delayed so i'll be waiting a while!)

Have tried to strip the calipers. Used an old pad, a G-clamp and the brake lever to get the pistons out evenly. Got them both nearly out, then one popped out. And the system immediately lost pressure (assumedly because there was no longer a seal), i.e. the lever was doing nothing. And putting the piston back in didn't seem to do anything. To make it worse, while i was messing around i let the master cylinder run out of brake fluid, so now there's an unknown amount of air in the system too!

So i tried to loosen the bleed valve to bleed the system so that i can use it to help me pump both pistons out again. And *snap*. Off comes the bleed valve screw, in half. This is a disaster. Have just ordered replacement from Wemoto. God knows when it'll arrive though! (maybe i'll be lucky and it'll arrive for friday, but i don't feel lucky )

Is anyone able to give me an alternative method/soothing words of encouragement, or perhaps if i'm really lucky has access to a compressor or something in South Wales (i'll come to you with my caliper, and happy to compensate! ) - i need to get these pistons out so i can get the calipers cleaned out and sealed again. And then hopefully this bleed valve will arrive and i won't have such a huge problem getting to work.

[rennie]

put the piston back in and hold it in with the g clamp

then bleed system enough to push other piston out.

can you get mole grips or something on what's left

of nipple?

[Ingah]

put the piston back in and hold it in with the g clamp

then bleed system enough to push other piston out.

can you get mole grips or something on what's left

of nipple?

 

That was the plan. Apart from there's nothing left sticking out, so i drilled into it with the vague intention of putting in some sort of thing to sort it out, but i'm not quite sure what i need to do this, so i then put the drill down lol.

Still need to get both these pistons out though, i figure once they're out, i can relax a little.

[rennie]

you can get stud extractors!

they're similar looking to drill bits

you screw them, left handed, into

the hole, they cut into what's left

of screw and pull it out. They have flats

on the end so that they can be turned with a spanner.

you can get various sizes, they tell you what size drill bit

to use.

be very, very careful that you don't use too big a drill

and damage the caliper.

not sure where to get them from try srewfix, or maybe RS