Brakes get really hot!

I just changed the front pads, since the previous ones were all worn out I had to push the cilinders back in to fit the new ones. As I was pushing I could see that the cylinders tend to come back out. Anyway I fit the pads and went riding. The front wheel is no longer spinning freely, if feels like the brakes are slightly applied and Disks get really hot.

What should I do? Do I have to let out some oil from the bleeding nipple?

Did you possibly get air into the system? Sounds like there is some in there since you said that the cylinders want to come back out when you push them in. That should never happen. Did you have the bleeders open at any time during the pad install?

I did bleed the rear one (including the linked front), but not the front one. The ones that want to come out is the left disk, which is not connected to the linked brakes.

Mmh, maybe I'll bleed the fron one too tomorrow

Sounds like the hydraulic system is too full after installing the new pads. Just let a squirt out from the bleeders.

Take the calipers off again and remove the pads. Extend the pistons (without pushing them all the way out) and clean them with brake cleaner. You probably have a lot of road spooge buildup on the part of the piston that was exposed and then shoved back into the calipers. That crud will cause the pistons to drag when being pushed in.

You can get to the back side of the pistons, for cleaning all the way around, by rotating them in their bores. There is nothing there to prevent them from turning except the friction of the seals, but that can be significant. Try sticking some expanding pliers (I use circlip pliers) inside the hollow pistons to help grab them to turn.

When the pistons are all cleaned up, the way that they should behave is that you should be able to push them into the calipers fully (watch out for fluid overflow at the reservoir) Then, after you use the lever to move the pistons out a little, when you release the lever you should see the piston retract ever so slightly. This is the action of the seal pulling the piston back in. That retraction is key in preventing brake drag.

Hope that helps

Justin said:

Sounds like the hydraulic system is too full after installing the new pads. Just let a squirt out from the bleeders.

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^^^^^^^^^^^ THIS ^^^^^^^^^^^^

Did you have the cover on the reservoir when you were pushing the cylinders back in ? You got some pressure in there somewhere ... Air could do it too ...

Awesome! Plenty of solutions to try tomorrow..

Txs guys, will update with what I find

Too much pressure had built inside, as soon as I removed the cover of the from brake oil reservoir, I felt a gush of air (and oil) coming out..

I took The opportunity to clean the brakes too, with brakes cleaner.

All back to normal now. Many thanks!

Glad you got the solution. Make sure you clean that brake fluid off of anything it gushed onto. Brake fluid is nasty stuff and will remove paint.

damianomigani said:

Too much pressure had built inside, as soon as I removed the cover of the from brake oil reservoir, I felt a gush of air (and oil) coming out.....

Click to expand...

That's kind of strange and may indicate a problem. The rubber diaphragm in the master cylinder should allow the fluid to rise/fall while acting as a barrier from outside moisture, there should also be white plastic piece with a small hole in it that prevents vacuum lock/pressure as fluid moves in/out of the master cylinder.

One item overlooked when folks replace brake pads, they compress the calipers but forget to removed fluid from the master cylinder. If the cylinder was topped off previously, it may overflow once the calipers are compressed. I'm guessing in your case, the master cylinder was simply "full up".

When was the last time you flushed the system? It's an every-other-year maintenance item because the fluid attracts moisture.

Even more detailed cleaning would be to clean and service the brake pistons.

Pull the pads, pull the pistons (drain fluids first). clean all around the dust covers and clean up the ring of sploog that builds up around the pistons with a scotch bright pad. Put everything back together and flush the system with new fluid. Failure to do this occasionally can cause the pistons to hang instead of move like they should.

Clean anything that got brake fluid on it. That stuff will eat paint and plastic aggressively.

Sounds to me like someone else said you have to much fluid in the system. The further the pads travel out the more fluid is needed. If by chance you had added fluid when the brakes were at there lowest point it is possible your trying to collapse the piston and the fluid has no where to go.

Other thing is make sure you havent kinked a line, causing the fluid to not be able to go back. Use to see that with older cars and the lines would kink inside.

If the pistons were slidding in and out ok, then it's doubtful you have a piston sticking in it's bore just from taking it a part. However it is possible and fairly easy to check by removing the pads again and checking out the operations. Just remember not to apply the brakes with out making sure the piston won't fly out.

You can use something like a turkey baster and suck some fluid out. Slowly push the piston in and see if it goes in ok. Then fill the fluid back up when she's all together.