Monster rear brakes - help!!

[Noggin]

Ok, so I went to do the 'simple' job of changing the rear brake pads.

Not so simple!!

TBF, the old pads don't look so bad!! But, after all the comments about 'glaze' (I think that's right!) I'll keep on going!!


Anyway, eventually sorted getting the pin out and the old pads out. Replacing them is ded simple!

Downside is that the pads touch in the middle - can't even attempt to get the disc in between them



(Forgot to take a pic of the pads in there and touching )


Ok, I thought, Just push the pistons back. Nope They don't both go right back.




So, how do I get both pistons to get right back? I've taken the top off the fluid reservoir. Didn't think to take the cover off the bleed nipple, would that make any difference?

I really really don't want to take the caliper apart. I'm worried that something will break and I won't be able to refit it at all!! LOL


I have brought the disc home with me to clean, off to read the other thread to remind myself what I need to do for that!! Don't have any brake cleaner here so have to see how that goes!!


Have to go back out to the garage later to have another go. I really really want to sort this!! I even found a couple of bits of wood to help get the wheel off and (hopefully) back in !!!!

[Yorick]

Get a big flat screwdriver and prise them apart.

[KungFooBob]

You could try loosening the bleed nipple to let excess fluid out when you push back, make sure you have a rag round if you do.

The piston might just be stiff, if you can get the pads in, you could use something to prise the piston back in against the pad.

[DefTrap]

They should both go back in if you have taken the top off the reservoir.

So either -
- you're not using enough pressure on the piston (use a c-clamp or something)
- it's seized.

[Noggin]

Get a big flat screwdriver and prise them apart.

Can't get a screwdriver in between the new pads, can only push one side back at a time with a screwdriver and when I do the other one comes out!!

You could try loosening the bleed nipple to let excess fluid out when you push back, make sure you have a rag round if you do.

The piston might just be stiff, if you can get the pads in, you could use something to prise the piston back in against the pad.

I didn't loosen the bleed nipple, so will try that later. Can't get anything between the new pads!!

They should both go back in if you have taken the top off the reservoir.

So either -
- you're not using enough pressure on the piston (use a c-clamp or something)
- it's seized.

They both move (with a good amount of pressure!!!) just not at the same time, one at a time and then the other comes back out!!

I don't think I have any c-clamps, been trying to think of anything I have that would hold the one back when I push the other.



I can see me just having to take the caliper off and bring it home to do a full clean!!

[Yorick]

Put one of the old pads in. That will let you get a screwdriver in to start it off

[DefTrap]

To be honest I always strip the caliper right down so I'm never pushing the pistons back in with any fluid still in the system. So yes take the MC cap off and loosen the bleed nipple, then the fluid will have somewhere to go that is easier than pushing the other piston back out iyswim.
Just be mindful that it's possible that you may need to bleed the system afterwards.

[Noggin]

Put one of the old pads in. That will let you get a screwdriver in to start it off

Good call. Will try that

To be honest I always strip the caliper right down so I'm never pushing the pistons back in with any fluid still in the system. So yes take the MC cap off and loosen the bleed nipple, then the fluid will have somewhere to go that is easier than pushing the other piston back out iyswim.
Just be mindful that it's possible that you may need to bleed the system afterwards.

I kind of wanted to, and did actually start to take it off! But I couldn't undo the banjo bolt It's already been a challenge with the half strength arm! But, if all else fails this afternoon, then I will try harder and this evenings job will be clean and sort out the caliper!!

But, I will have another go at getting the pads and disc in - I didn't undo the bleed nipple earlier, so that might be the final 'help'!!

[Demannu]

Put the old pads back in, then get a bfo screwdriver/tyre lever/crowbar between them and lever the pistons back all the way. Make sure you have some rag around the reservoir as well!
Easier if the caliper is bolted to bike! You'll never hold it by hand!

[Noggin]

The old pads weren't exactly worn, but don't feel very grippy (they feel more shiny!!) - I haven't compared with the new pads as by this time my hands were dirty as hell and I don't want to ruin the new pads with mucky finger prints!!




Not sure what to used to clean these disc bolts, or if I should just reuse and add a smidge of loctite to be sure they stay put!!

[A_morti]

Get a big flat screwdriver and prise them apart.

No no no - not on Brembos. The pistons are aluminium and you'll deform them.

Are they both moving ok but just not at the same time?

If one of them is more reluctant than the other, could be it's not moving when you use the brake normally, which would definitely reduce brake effectiveness. The cure for that is to strip it down, take everything apart, clean, refit, bleed.

Put one of the old pads in. That will let you get a screwdriver in to start it off

If they're both moving freely but just not at the same time, probably you're just not applying enough force and Yoz's tip will do the trick (that's what she said).

If Yoz's idea doesn't work then considering how old and manky the bike is, it could also be something like an internally-collapsed brake hose or master cylinder with blocked fluid transfer port, which would both stop fluid going up into the reservoir. You could loosen the hose at the top of the master cylinder, if fluid comes out easily there then the hose is fine. After that you're into rebuilding the master cylinder.

Don't be scared of brakes. Be methodical, work in a clean space, take your time.. it'll be fine.

[Noggin]

Get a big flat screwdriver and prise them apart.

No no no - not on Brembos. The pistons are aluminium and you'll deform them.

Are they both moving ok but just not at the same time?

If one of them is more reluctant than the other, could be it's not moving when you use the brake normally, which would definitely reduce brake effectiveness. The cure for that is to strip it down, take everything apart, clean, refit, bleed.

Put one of the old pads in. That will let you get a screwdriver in to start it off

If they're both moving freely but just not at the same time, probably you're just not applying enough force and Yoz's tip will do the trick (that's what she said).

If Yoz's idea doesn't work then considering how old and manky the bike is, it could also be something like an internally-collapsed brake hose or master cylinder with blocked fluid transfer port, which would both stop fluid going up into the reservoir. You could loosen the hose at the top of the master cylinder, if fluid comes out easily there then the hose is fine. After that you're into rebuilding the master cylinder.

Don't be scared of brakes. Be methodical, work in a clean space, take your time.. it'll be fine.

Will give this a go later. I'm writing a list!!

I really don't want to have to argue to get the banjo undone or to take apart the caliper. But if I have to I have to!

The hoses 'look' ok, but hadn't thought of collapsing inside!!

[DefTrap]

Be careful using too much welly to undo a bleed nipple, if it's corroded at all they can just snap off. Don't want to worry you too much, just go gently.

Those disc bolts are just a bit manky and probably have a bit of old loctite on them. Just wire brush the threads.
I have to say I never bother using loctite on disc bolts, even though I have it. Five bolts coming loose, in an application where they're already under a degree of tension such that they're unlikely to loosen? I just don't see it, and I've changed loads of discs over the years. But I'm lazy! Use it if you have it.

[Noggin]

Be careful using too much welly to undo a bleed nipple, if it's corroded at all they can just snap off. Don't want to worry you too much, just go gently.

Eek!! Didn't try that one but the others I've done today have all been tight - whether it's loctite or that combined with corrosion I'm not sure!!

But, I'll go careful

Those disc bolts are just a bit manky and probably have a bit of old loctite on them. Just wire brush the threads.
I have to say I never bother using loctite on disc bolts, even though I have it. Five bolts coming loose, in an application where they're already under a degree of tension such that they're unlikely to loosen? I just don't see it, and I've changed loads of discs over the years. But I'm lazy! Use it if you have it.

Sadly I have no wire brush!! (I don't seem to be very well equipped anymore!! ) Got to ask around to see if anyone has any brake cleaner as well

[A_morti]

Bleed nipples on brembo are much bigger than on Japanese brakes. M10 thread I think. They take something daft like an 11mm socket IIRC? Anyway you're not at such risk of breaking them off nor rounding them out, as you are on eg a Honda.

If you have blue loctite for the disc bolts may as well use it. The risk isn't so much all 5 coming out and the disc flying off, it's one coming out and eating its way through whatever is nearest, probably the caliper carrier.

[The Spin Doctor]

Noggs

You could try loosening the bleed nipple to let excess fluid out when you push back, make sure you have a rag round if you do.

The piston might just be stiff, if you can get the pads in, you could use something to prise the piston back in against the pad.

Once upon a time I couldn't get the pistons to move either when I replaced the pads on a bike I'd bought. Turned out the previous owner had 'topped up' the brake fluid to the 'FULL' line on the master cylinder with the pads 3/4 worn. So no matter how hard I tried to move the pistons (and I'd done all the usual stuff like cleaning the pistons up) they wouldn't move because there was nowhere for the fluid to go.

The solution was to stick some old battery pipe over the top of the bleed nipple and feed it to a milk bottle, loosen the bleed nipple, and then ease the pads apart. Now with the pressure off, they moved easily.

[Zimbo]

The pistons should push right back so sounds like the fluid just isn't getting pushed back past the master cylinder to the reservoir.
Those Brembo rear master cylinders do gave a habit of doing this, I've had monster rear brakes stick on and seize the rear wheel due to this in the past. A change of master cylinder sorted it (they're not expensive) but your existing one may just need a strip and clean perhaps? Very unlikely the caliper is faulty and needs disassembling, they're pretty reliable!

[Noggin]

Well, I got the pistons back and the pads in




Stupidly, I forgot to take a photo of the caliper bracket set up before I took it all apart So am about to go look up how it reassembles - cos it ain't the way I did it!!

And, only managed to skin one knuckle whilst trying to release the bleed nipple!!!

Noggs

Once upon a time I couldn't get the pistons to move either when I replaced the pads on a bike I'd bought. Turned out the previous owner had 'topped up' the brake fluid to the 'FULL' line on the master cylinder with the pads 3/4 worn. So no matter how hard I tried to move the pistons (and I'd done all the usual stuff like cleaning the pistons up) they wouldn't move because there was nowhere for the fluid to go.

The solution was to stick some old battery pipe over the top of the bleed nipple and feed it to a milk bottle, loosen the bleed nipple, and then ease the pads apart. Now with the pressure off, they moved easily.

The fluid wasn't too full (and definitely needs topping up now!! Wish I'd thought of putting some pipe on the bleed nipple !! ) Once the fluid could come out of the bleed nipple, I could get both pistons back. Which makes me think that what Zimbo says about the master cylinder could be right (I've never messed with that side of brakes - only ever done pads and discs!! LOL )

I do think the pistons are too stiff moving. But not sure! Once all is back together, topped up and bled, I'll do a little test ride up here to see if it's any different to before!!

The pistons should push right back so sounds like the fluid just isn't getting pushed back past the master cylinder to the reservoir.
Those Brembo rear master cylinders do gave a habit of doing this, I've had monster rear brakes stick on and seize the rear wheel due to this in the past. A change of master cylinder sorted it (they're not expensive) but your existing one may just need a strip and clean perhaps? Very unlikely the caliper is faulty and needs disassembling, they're pretty reliable!

They were very stiff to push. I know I'm not that strong, but I had expected to push them back with my fingers!!

I'll have a look and see if I think I can strip and clean the master cylinder. I haven't pressed the brake lever yet as will wait, maybe, till I'm ready to bleed the brakes!!

If it's no better after a test ride, I'll look at the master cylinder

[The Spin Doctor]

Well, I got the pistons back and the pads in

They were very stiff to push. I know I'm not that strong, but I had expected to push them back with my fingers!!

I'll have a look and see if I think I can strip and clean the master cylinder. I haven't pressed the brake lever yet as will wait, maybe, till I'm ready to bleed the brakes!!

If it's no better after a test ride, I'll look at the master cylinder

Well done

I have two steel tyre irons where I bent a kink about 2" from one end... I've got a strong rubber band around the point where they are kinked to hold them together back to back. So you put them in between the OLD pads side by side and then squeeze the long side together, the other end forces the pads and pistons apart... gives you lots of mechanical leverage.

[Noggin]

Well, I got the pistons back and the pads in

They were very stiff to push. I know I'm not that strong, but I had expected to push them back with my fingers!!

I'll have a look and see if I think I can strip and clean the master cylinder. I haven't pressed the brake lever yet as will wait, maybe, till I'm ready to bleed the brakes!!

If it's no better after a test ride, I'll look at the master cylinder

Well done

I have two steel tyre irons where I bent a kink about 2" from one end... I've got a strong rubber band around the point where they are kinked to hold them together back to back. So you put them in between the OLD pads side by side and then squeeze the long side together, the other end forces the pads and pistons apart... gives you lots of mechanical leverage.

Ill be honest, I don't ever want to do this again on this bike!! LOL But if I do, I'll come back and reread!! LOL

Thank you