Brakes stuck on?

[Jonno.]

Well I've just bled my brakes and they're nice and firm, however the pads are stuck to the disk; I can move the wheel, but just. When I pump the lever the wheel won't move (as it should).

It is both calipers and it is physically hard to get the calipers off of the disk.

How far should the pistons retract? Should I be able to push them back while the system has been bled? I've tried looking but I've got no idea.

Thanks!

[blackdog]

take it for a spin.... they should free up after a couple of hard applications

[Jonno.]

The wheels barely turn when the lever is released though?

[blackdog]

i'd still give it a go..... the other option is to take the caliper off and lever the pads back a bit (remember to take the cap off the master cylinder)

[Blackflagged]

Let some oil out, of the bleed nipple, check for air.Let the lever go at least half way to the bar.Close the bleed nipple and then pump brakes and see if it does it again, they should release normally.

[Jonno.]

There are two pistons which can't be pushed back out and when I try to do each it pushes the other out?
The master cylinder fluid isn't going up. Something must be blocked? Yet the lever and action still works

[blackdog]

dont think its blocked, after all, it bled alright. u just need to find a way of pushing apart the pads and the fluid should travel back to the resevoir

[Jonno.]

That's the thing, it won't go up to the reservoir. It will however come out of the bleed nipple. Maybe a return valve in the MC?

[CookMySock]

Nah don't ride it. Pull the lot off and service it. Don't be afraid of them - brakes aren't rocket science. Just work in a clean tray like a paint tray from bunnings ($3) and carefully pull it apart without scratching any surfaces. There will just be circlips and screws and a banjo fitting or two.

Clean the corrosion off everything, wash and dry it (dry it very well!) and reassemble it wetted out with lots of clean new brake fluid. Unlikely anything is busted - it will just be jammed with a little corrosion.

Steve

[Jonno.]

The brakes were fine before and the pistons retracts when forced with the nipple off; there seems to be a pressure build up and liquid can't go back up the master cylinder (ie trying making them go back in when the nipple is closed).

Edit: this seems to be consistant with when I tried to bleed the brakes via pushing fluid up the nipple. You could push it up but it was forced out almost like it couldn't get past the MC. But is fine coming the other way?

[quickbuck]

Have you even bothered to read the other thread you asked the question on?

To get the pistons to Retract it is BEST if you have the bleed nipples open.
It also pays to have the old pads in so you can get a big leaver in there to pry them apart enough to get the new pads in.....

There is no check valve, other wise your pads would NEVER come off the discs.


What there is, it a piston with seals on it that forces fluid down to the calipers every time you pull on the lever.

[Jonno.]

Of course I read that. I've been searching all day before I posted this.

How far should the pistons retract after being bleed? Should I be able to push them back after the system has been bled?

[CookMySock]

How far should the pistons retract after being bleed? Should I be able to push them back after the system has been bled?

The pistons dont retract at all when you release the pedal/lever. They just relax their pressure against the disc. Thats how they auto-adjust themselves up.

Strip and service time.

Steve

[quickbuck]

Of course I read that. I've been searching all day before I posted this.

How far should the pistons retract after being bleed? Should I be able to push them back after the system has been bled?

They will have a gap of about 0.010" when the pressure from the leaver is released.

If you try to push them back, you will be trying to squeeze fluid back into your master cylinder past the piston in there.... If the cap is on, you may actually find this very difficult, as the cylinder will be quite full.....

Remember a Brake system is actually a CLOSED Hydraulic System.... Hence the requirement to get all the air out.

The Pressure on the pads works only one way.

[p.dath]

Might it not be easiest to pretend you are replacing the pads?

Tape the pads out, use a G-Clamp, and force the pistons back (as if fitting new "bigger" pads). You Tube has lots of videos on the issue.