brakes

[mattrick]

just changed front brake pads and now front brake lever is very flat and pads are not holding the disc.do i need to bleed brakes or have i damaged caliper pushing back the pistons.i took the lid of master cylinder to push pistons back because it was so stiff and blew all the fluid out leaving the chamber empty and therfore leaving air in the when i toped it up.losened nut on caliper(fluid line)and pumped brake but no pressure build up at all.not sure if i losened right nut as ive never bled brakes before.i changed brake pads before but dont remember having to bleed them afterwards.what have i done wrong. thanks.

[scrowe]

Hiya,

It sounds like you have managed to get air in to the system and yup, you will need to bleed them.

Bleeding brakes is an excercise in patients at the best of time (i just put on braided lines and it took a few hours to get them right).

i'd say go to halfords and get some fresh fluid and a bleeding kit, they cost £5 or so, all it is is a clear pipe with a one way valve on one end to spot air going back in to the caliper, the other end fits over the bleed nipple. un do the nipple a half turn and slowly pump the lever. when the lever gets to the bar do up the nipple, relese lever, undo nipple and pump lever.

repeat pumping and nipple action untill firm!! oooh errrr!

it is pain in the backside and it will take time but be patient and all will be good. don't forget a beer while you're at it. it helps the teedium.

hope this helps.

[skatefreak]

Hey,

Yeah, went through this last night, if there is no pressure ont he handle then that means there is air in there that is compressing (and the brake fluid is designed to resist compression). If you have a spair pair of hands willing to hep you, do what i did!

Open the top of the resivour, fill it to the top (get the other person to hold the bike upright),

Get them to squeeze the lever and whilst it is compressed, open the nut to let some fluid out,

be SURE the nut is then closed BEFORE the brake grip is released,

once released, get them to pull it again and the cycle repeats.

This wayas long as you open the nut very quickly and close it again whilst the brake is pulled back it will stop air traveling backwards through the system into the caliper.

If you let air get down into the tube going to the break caliper it may take a whlie to get the air out as it only comes out little by little but bleeding should get it out.

Once the air is out then the break handle will feel stiffer again and the brake pads should make it to the disk easy

Hope this helps somewhat

Best regards

-Jvr

[mattrick]

thanks guys.funny enough just after i posted this i went to halfords and bought the exact same kit you described for a tenner just one quick question that might sound stupid ? the one way valve in the kit has an arrow on it.should the arrow be pointing towards the nipple or away. thanks

[skatefreak]

Away from the nipple i would expect.

Its to stop air going back up the tube and into the caliper

Best of luck, get us know if it helps

-Jvr

[mattrick]

thank you very much.will do.