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Brakes dragging

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Both my front AND rear brakes are dragging. The rear is much more severe than the front. the rear tire will barely do one full rotation with the chain off, and the bearings are fine, I know this because I took the caliper off and the wheel did 10 or so rotations before it stopped.

The Oil reservoir appears to be filled to the very top, front and back. But the front only drags because of the trip counter, it has very little to do with the brakes.

My question is, should i remove some of the oil? and will the pads spread open farther if i do this?

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How worn/thick are the brake pads?

Is the brake rotor worn thinner than the recommended 4mm minimum?

Pull the pads and make sure the pins are free of dirt/corrosion.

Fill the reservoir no higher than the full line.

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No that will not fix the problem. First check your brake rotors then the electronic trip counter. If the trip counter is dragging than get your wheels balanced by a reasonable shop for about 30 bucks.

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How worn/thick are the brake pads?

Is the brake rotor worn thinner than the recommended 4mm minimum?

Pull the pads and make sure the pins are free of dirt/corrosion.

Fill the reservoir no higher than the full line.

Okay, ill measure my rotor soon, but idk how that would make it drag, Ill check the pins, the pads still have a substantial amount of material on them and i have to remove oil, which is probably the problem.

No that will not fix the problem. First check your brake rotors then the electronic trip counter. If the trip counter is dragging than get your wheels balanced by a reasonable shop for about 30 bucks.

electronic trip counter? ohhh... haha my bad, its on the axle, shoulda said that in the original post.4

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A combination of worn/gone pads and a thin rotor cause the caliper pistons to be out of their bores a significant amount. Any corrosion or built up crud on the exposed piston can prevent it from retracting. If it's really sticking out there, it's possible the piston can become cocked in it's bore. That's why I asked those questions.

Yes, removing brake fluid from the res. will allow the pads/pistons to be retracted further before hydro lock of the system. Having the pads seated fully/tight against the rotor and then filling the res. completely full leaves no cushion in the system.

You know that rubber seal in the res cap?.......it has a built in fluid level compensation device. It extends and retracts with the flow of fluid thru the res., helps maintain a minimum level of fluid in the res. to prevent air entrainment and acts as a cushion for the system when retracting the caliper pistons, forcing fluid back into the res.. So never fill it above the marked full line.

Okay, ill measure my rotor soon, but idk how that would make it drag, Ill check the pins, the pads still have a substantial amount of material on them and i have to remove oil, which is probably the problem.

/QUOTE]

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Yes be sure you have not overfilled the res. Also be sure the little vent slot in the cap is not full of dirt. The rubber insert should fit in without forcing fliud out and leave an airspace under the cap.

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The brakes drag because the piston won't retract after applying the brakes. Two causes:

A common problem with disk brake is the pistons stick develop corrosion in the bores from water and this causes the pistons to hang. The water can be on the outside from pressure washing or on the inside from not bleeding the brakes often enough. The fix is a rebuild of the caliper.

Another problem is corrosion or adjustment that prevents the master cylinder piston from retracting far enough after release of the brakes to uncover the vent hole to the fluid resorvoir.

If you pull the caliper or master cylinder you can check the piston travel by applying compressed air to the hose port (leave the pads in), the piston(s) should move with about 40psi pressure. You can tell when the master cylinder piston fully retracts because air will vent thru the port to the resorvoir. If you need much more than this pressure to make the pistons move thay are sticking.

I had a master cylinder with a frozen piston that required 150psi air to get the piston out, also several caliper pistons that needed 120psi to move. All needed rebuild kits.

On two piston calipers I rebuilt the mstr cylinder and threw the calipers into the parts bin for a future project.

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This happend on my KX, the brake pads wore out so much that the pistons popped out and wouldn't go back in. To fix this take the caliper off and buy some new caliper (piston) seals, brake pads, and blead the lines. I'll post pics if you need them. :thumbsup:

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