Brake cynlinder wont retract

[larsliederhausen]

Hello I'm new to scooters. Just bought my 2012 Jonway yy250t 54B 08/14/2012. I've had it for a month now and having a problem with my front brake. First I noticed that I lost pressure in my lever, then I noticed that the brakes were closed onto the rotor but wont retract. Every time I squeezed the lever I did notice a drip of brake fluid that would drip out of the bolt. (If you follow the brake line down it leads to a bolt on top of this vertical cylinder piece. The cylinder piece has a brass bolt that goes into the side of it with an o-ring and 2 brass nuts. This bolt that connects to the vertical cylinder is where it was leaking.) I wrapped some teflon tape around the threads. Filled the reservoir, bleed all the air out and got good pressure but the pistons are stuck. I did push the cylinders back in and kept squeezing the lever but then they would only work their way out but never retract. Any suggestions?If I have to buy the new piece..any suggestions where for this part? I've been to several sites that say "Jonway scooter parts" but they either look different or they want to sell me the lever and line altogether. Please help.

[rockynv]

On disk brakes the pistons don't really retract which is why you do not have to adjust them as they are in effect self adjusting. As long as they release the rotor and the wheel spins relatively freely you should be OK.

If the part is defective shouldn't you just make a claim on the warranty and have them send you all the new parts required? If they play it safe and send you an entire sealed system then that would be just grand.

[larsliederhausen]

The wheel does not spin freely however good point i'll review my warranty.

[ronlee]

Do you think there is any possibility that you wrapped the threads too close to the end with Teflon tape and some of it got in the system and is plugging the return of fluid preventing the releasing the caliper?
One must be really careful using Teflon tape on anything with small orfices such as carburetors etc. that could get plugged with fragments of it. The bad part is that nothing dissolves the stuff.
Always leave two threads on the end showing. When taking a joint apart and reassembling be very careful to clean ALL fragments from the female and male parts.

[leo]

Sept 17, 2012 2:28:24 GMT -5 larsliederhausen said:

First I noticed that I lost pressure in my lever, . . .

wipe the master cylinder clean of all dirt, remove the lid, then fill with DOT3 or above brake fluid.
replace cap on brake fluid can tightly because brake fluid absorbs moisture from the air.
replace cylinder lid and squeeze the lever a few times.
if the cylinder is full of fluid and you still can't get pressure by pumping then the cylinder is bad.
if you can "pump up" the brakes and have to keep doing it then you have a loose fitting or air in the lines.

. . . then I noticed that the brakes were closed onto the rotor but wont retract.

normal for disc brakes.

Every time I squeezed the lever I did notice a drip of brake fluid that would drip out of the bolt.
I wrapped some teflon tape around the threads.

be very careful about doing this.
mine and a lot of others use what are called "banjo fittings".
these fittings have bolts with holes drilled in them to allow fluid to pass through them.
wrapping these bolts with teflon tape is not a good idea.
you need to replace the o-ring and copper washers instead.

I did push the cylinders back in and kept squeezing the lever but then they would only work their way out but never retract.

like i said, it's normal for disc brake pads to be very close to the rotor, maybe even a slight rub.
the rotor is the part that is bolted to the wheel (or rim).

[rockynv]

Leo good point on the banjo bolt. We really should not use pipe dope or tape on brake system connections as they have their own flanged, flaired or gasketed seals. Using pipe tape or pipe dope will only introduce particles into the sealed system and lead to an eventual premature failure.