Seized caliper

[Gazz]

Bought a bike which I suspect had been sitting for a while. The brake lever was coming back and touching the handlebars. Managed to trace it back to the pistons not moving when the lever is pressed.

Does anyone have any suggestions on a quick fix for this even if it is just a temporary fix.

If you hold something between the other 2 pistons, the pressure forces the stuck one(s) out. Then when you push that one down another one pops up, etc but they don't appear to want to all move outwards at the same time. ( I hope I've described that better than I think I have).

[NJD]

Time for a rebuild.
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[Nobby the Bastard]

Sounds.like it needs.bleeding.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[cresad]

Hi

I've been going through a similar problem with my new bike , ended up sending them away to get them refurbished £ 55 a caliper , gives it shot blasted , repainted , new seals and new pistons. Can't get the parts and do it myself for that , found then on the #bay.

[Gazz]

[Gazz]

[Teflon-Mike]

[martin734]

IMHO I never think it is a good idea to try quick or cheap fixes when it comes to brakes. If the brake calipers are seized then there is corrosion in there somewhere and that corrosion is not going to go away without stripping, cleaning and rebuilding the caliper. If you don't do a thorough job they will seize again or the seals will fail and you could well end up with brake fluid all over your discs and pads.
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Current bike: ST1100 "Big Red"

[sickpup]

[Easy-X]

[Gazz]

I should have mentioned that the lever only comes back and touches the bar on the first press.

The previous owner had just fitted new discs and pads and it had blue fluid in the reservoir.

I first assumed that there was air in the system so I bled it. The problem was still there.

It was suggested a couple of times that it may have been a faulty master cylinder as they are a known fault on these bikes. I bought 2 by mistake fitted one and the same problem existed.

It was also recommended that I check for seized pistons. Checked them and they don't all move until they are manipulated.

I'll try and find a video of the lever.

[sickpup]

There are only 2 things it could really be, air in the system or duff master cylinder seals.

I'm leaning towards master cylinder seals as every vehicle I've had niggling brake problems with I've changed the master cylinder for a brand new one or done the seals and they have worked perfectly.

[stinkwheel]

If the pistons aren't moving, the lever should be soild.

If it isn't, there is a leaky seal or air in the system.

But hang on. What EXACTLY is happening? You say only on the first press? Does that mean it then firms up on subsequent presses? Does the brake engage then? What then, do you ride it a bit and it goes loose again? Because that can be a sign of warped rotors.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Hong Kong Phooey]

Yes, sounds like pad knockback. Check runout on disc(s).
What bike? 2010 Sprint?

If you're rebuilding, due to sticking pistons then you might be able to salvage the pistons and just change the seals.
https://www.ebay.co.uk/itm/164015584664
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'81 CG125, '97 FZS600 : '99 CBR600F4, '09 KTM RC8

[Gazz]

Hope this works :

https://vimeo.com/397859043

Its been like that since I bought the bike. Pervious owner said that he had just fitted new discs and pads and put new fluid in it (blue stuff) so he obviously knew that there was some sort of issue and tried to rectify it before reselling the bike on to me.

Without going into detail about the previous owner, (that's for another day to discuss) I'd just like to get the issue sorted so that I can finally use the bike.

Firstly I bled the brakes, thinking that was the issue, then bought and fitted new master cylinder (2 of) , rebled, exact same issue there.

Checked pistons, some of them don't move; but all move when you hold the one down that moves freely and pump the lever.

[Gazz]

[sickpup]

[Gazz]

Was out at the bike this morning for a bit.

Cleaned the pistons (didn't remove them completely just moved them out a bit) and the inside of the caliper.

As I may have mentioned before; The calipers are near spotless and so are the condition of the pistons by the looks of things. Bled the brakes again after I had finished and the problem still exists.

Brake lever only stiffens up on the second pull.

All pistons move just not in unison with each other when the lever is pressed. Don't know if this is normal or not.

Any other suggestions?

[Easy-X]

[Hong Kong Phooey]

[jaffa90]

Looking at your video and the use of one finger with ease tells me the master cylinder seals are not sealing. Which has been mentioned.

[sickpup]

[Nobby the Bastard]

I'm with sickpup on this. I've had a bike that had a distinct pulse when pulling the (non abs) brake due to the disk not being true but it was never spongy and the brake lever never even close to going back to the bars.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[Hong Kong Phooey]

[sickpup]