Tektro HDC-330 hydraulic disc brake piston stuck up

supersaian

Hello, I am a newbie rider and using diac brake the first time. My bjke is not more than a month age. i found the front wheel brake rubbing the rotar last night, and removed the brake out. Found that seems only the left piston is moving, so i held the left piston firm and press the brake lever, then the right poston moves out. Then i try to push back both piston to its home position but they just can not. When i push in the left piston, the right piston moves out and vice versa. Finally I inserted back the pads and increase the gap by using a screw driver.

Finally the front wheel is installed back, but i found there is no space identified by eyeball between the pads and the rotar now, and the rotar is rubbing the pads continously. What can i do to improve the situation?

Any help is very much appreciated.

The Rookie

All normal, a small amount of rubbing is perfectly normal, if you have a gap then you won't have good brakes, the leverage ratio with hydraulic discs is high so the pads can't move far. With no resistance it's normal for one piston to have less resistance than the other, just a tiny amount and it will do as you describe, likewise when trying to push them back, you have to reduce the volume of fluid downstream of the piston by forcing it back into the reservoir.

You can make sure the calliper is aligned correctly with the disc, but if the pads are worn off square they will rub a bit while they wear back straight.

rmissin

I have the same issue with the front brakes of my Mongoose 29'er, brand new and there's a slight rubbing, nothing excessive, I've searched the web and from what I can find out you can't adjust these brakes.
Basically ride it till it wears in ?

The Rookie

Rubbing is normal, just go ride the bike!