Brembo caliper advice

Hi all,

I am not having the best luck with the bike at the minute. I thought the front brakes were rubbish so I did the disc, pads and braided line. They binded up a little when I refitted the wheel but I figured I just didn't recess the pistons enough and that they would wear in, which they did. The problem is that the stopping power is still rubbish and the lever is really firm. I gave them a really hard squeeze when I was stationary and stopping power is better now but they are now binding up again. 

Does this mean that the pistons are just junk? The callipers leaked when I bought it and I had the seals replaced. I assume replacing these meant removing the pistons etc so if they are still bad on reassembly with a new seals does that mean the caliber has had it? They float around eBay used for around £40 so I was considering a punt if you guys think that is the way to go. I just don't want to end up with another junk used caliper and all the fitting/bleeding carry on that goes with it.

Any thoughts?

If it's had new disc, pads, line, and piston seals then maybe the problem is with the master cylinder?
You could try a rebuild or replace that.
That's assuming there's no leaks, not sure if you meant the caliper is still leaking after the new seals or just general crapness. You can replace the pistons, there are piston & seal kits on David Silver Spares or Wemoto.

First though you could check the fluid level. Could just be too high?

I had not considered the master cylinder. There is no leaking at the minute, just crapness. The pistons were difficult to recess when I fitted then new pads. I remember doing the much larger ones on my car by hand! On the bike they required some fairly ignorant prying to get them to receed. I am not sure how much effort should be required on these brakes but I am imagining much less

Corrosion on the caliper sliding pins can cause binding.

Did you take the m/c cap off before pushing back the pistons? It can make quite a difference.

I replaced the sliding pin because it looking pretty corroded and the master cylinder cap was off when I did the pistons.

Check the sliding pins on the caliper carrier (bit which bolts to the fork).
These are renowned for seizing, when you get it separated give it a good coating of red rubber grease.

Hi teamster, which part in this image are you referring to?

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HI,
just back from my garage having replaced one brembo caliper with another. I had been having a few uneven lever movement issues before the brake kicked in, no loss of braking power though. Today I found that the pins on the carrier were corroded and free of grease so changed them too. The lever has some play so will do a bleed through again and see how it all goes when I test it later.

To help sort this one I've previously changed the piston seals. No improvement but worth making sure there's no scrapes etc on the brake pistons, that will render them useless if they impinge movement.

I changed the master cylinder workings too with a kit from wemoto and this helped a lot. If you get a kit, make sure its for brembo not nissin master cyl. Getting the circlip out is impossible without the right tool mind.

atb

muttley1

liverpool_f_ wrote:I had not considered the master cylinder. There is no leaking at the minute, just crapness. The pistons were difficult to recess when I fitted then new pads. I remember doing the much larger ones on my car by hand! On the bike they required some fairly ignorant prying to get them to receed. I am not sure how much effort should be required on these brakes but I am imagining much less

If you were rebuilding the caliper then you should be able to push the pistons home by hand, assuming the air from behind them can escape through the banjo-bolt hole.

Your pistons were still on the bike and had fluid behind them, so when you push them in you are pushing the fluid back up the line and into the reservoir - this can be more difficult as there is only a small hole for the fluid to get back into the reservoir.

It also can be more difficult if there is a load of crap on your pistons, but I guess you might have cleaned that off while you were changing the pads.

Anyway, I also agree with everyone who says you should look at the master cylinder: the rebuild kit isn't too expensive (a bit over 30 quid on wemoto for the Honda original kit) and even if you don't need to rebuild it now it is good to rule it out plus you will then be safe in the knowledge it won't need doing again for a good while.

liverpool_f_ wrote:Hi teamster, which part in this image are you referring to?

They are not numbered separately on there, see circled parts:

You say you had the seals replaced - when this was done, was a just a quick seal replace or did the peron who did the work do a proper job and thoroughly clean out the seal groove/seat? Crud that builds up behind the seal pushes it out, which causes the seal to "grab" the piston and make it hard to move. The sysmptoms you describe of the piston being hard to push in and the brake binding suggest this.

If they just changed the seals, then you still have the same problem as before, which is just going to get worse.

Looks like this and needs to be removed:

Thanks for the reply teamster. As for the seals, I am not sure how thorough a job they did. The callipers were leaking before so maybe they just stuck the new seals in to fix that problem and didn't refurb the calliper. I think I will send it off to a specialist. I have found one that will do a complete refurb for £39 so can't complain too much about that!